Ergänzende Informationen zu Publikationen von Bruno Baur

Knowledge of patterns of genetic diversity in populations of threatened species is vital for their effective conservation. However, destructive sampling should be avoided in threatened species so as not to additionally increase the risk of local population extinction. We exclusively used beetle remains and beetles collected after death to analyze local and regional patterns of genetic variation in the endangered flightless longhorn beetle Iberodorcadion fuliginator in the border region of Switzerland, France and Germany, in grassland remnants. We extracted DNA from the beetles’ remains and genotyped 243 individuals at 6 microsatellite loci. We found moderate genetic differentiation between populations, each belonging to one of two metapopulations situated on either side of the river Rhine, but distinct genetic differentiation between populations across metapopulation. The genetic distance between populations was correlated with the geographic distance between the sites sampled. Genetic structure analysis inferred the presence of two genetic clusters. The populations in the Alsace (France) represent one cluster, together with the Swiss populations near Basel, which is separated by the river Rhine from the cluster composed of the populations in southwestern Germany. Thus, the historical separation by the river Rhine surpasses more recent effects of human induced habitat fragmentation on the genetic differentiation in I. fuliginator.

Keywords: agricultural intensification - Cerambicidae - habitat degradation - habitat fragmentation - insect decline - microsatellites - natural barrier - non-invasive method - semi-natural grassland - species conservation

Variation in community composition and species turnover are different types of beta diversity, expressing nondirectional and directional changes, respectively. While directional changes (e.g. turnover) along geographic gradients can be studied in any direction depending on the hypothesis of interest to researchers, temporal changes can only be meaningfully studied from past to present. Although a wide variety of methods exist for partitioning variation and related community-level phenomena such as similarity, richness difference and nestedness, approaches evaluating species turnover along geographic or temporal gradients, based on an analogous conceptual framework, are rare. We therefore look into the possibilities for examining different aspects of directional changes along a gradient when presence-absence community data are available. Measures of community overlap, as well as species loss and gain from one sampling unit to another along a gradient are combined to define a variety of turnover and nestedness concepts and to derive functions for their quantification. Each concept represents an ecological phenomenon to be indicated (indicandum), whereas measures (indicators) quantify relevant properties of these concepts. The measures use the raw number of species as well as relativized forms in accordance with the well-known Jaccard and Sorensen indices. The main innovation is the development of new measures of directional community change. We demonstrate differences between traditional nondirectional and the new directional measures and use several examples to show that actual communities display directional responses to a particular ecological gradient. The new measures therefore reveal an uncovered aspect of community ecology.

Keywords: components of beta diversity - directional community indices - gradient analysis - nestedness - presence-absence data - turnover

Elevational gradients along mountain slopes offer opportunities to study key factors shaping species diversity patterns. Several environmental factors change over short distances along the elevational gradient in predictable ways. However, different taxa respond to these fac- tors differently resulting in various proposed models for biodiversity patterns along eleva- tional transects. Using a multi-taxa approach, we investigated the effects of elevation, area, habitat and soil characteristics on species richness, individual abundance and species com- position of six groups of ground-dwelling arthropods along four transect lines in the Swiss National Park and its surroundings (Eastern Alps). Spiders, millipedes, centipedes, ants, ground beetles and rove beetles were sampled using standardized methods (pitfall traps, cardboard traps, visual search) in 65 sites spanning an elevational range from 1800 to 2750 m a.s.l.. A total of 14,782 individuals comprising 248 species were collected (86 spider, 74 rove beetle, 34 ground beetle, 21 millipede, 19 centipede and 14 ant species). Linear mixed model-analysis revealed that rarefied species richness in five out of the six arthropod groups was affected by elevation (the quadratic term of elevation provided the best fit in most cases). We found three different patterns (linear decrease in centipedes, low elevation pla- teau followed by a decrease in ants and rove beetles, and midpoint peak in spiders and milli- pedes). These patterns were only partially mirrored when considering individual abundance. Elevation influenced species composition in all groups examined. Overall, elevation was the most important factor explaining the diversity patterns, while most local habitat and soil char- acteristics have little influence on these patterns. Our study supports the importance of using multi-taxa approaches when examining effects of elevational gradients. Considering only a single group may result in misleading findings for overall biodiversity.

Population size of species with birth-pulse life-cycles varies both within and between seasons, but most population dynamics models assume that a population can be characterised adequately by a single number within a season. However, within-season dynamics can sometimes be too substantial to be ignored when modelling dynamics between seasons. Typical examples are insect populations or migratory animals. Numerous models for only between-season dynamics exist, but very few have combined dynamics at both temporal scales.
In a new approach, we extend appreciably the models of Dennis et al. (2016b): we show how to adapt them for a generation time > 1 year and fit an integrated population model for multiple data types, by maximising a joint likelihood for population counts of unmarked individuals and capture–recapture data from a study with marked individuals. We illustrate the approach using annual monitoring data for the endangered flightless beetle Iberodorcadion fuliginator from 18 populations in the Upper Rhine Valley for 1998–2016, with a 2-year life cycle. Standard likelihood methods are used for model fitting and comparison, and a concentrated (profile) likelihood approach provides computational efficiency.
Additional information from the capture–recapture data makes the population model more robust and, importantly, enables true, rather than relative, abundance to be estimated. A dynamic stopover model provides estimates of both survival and phenology parameters within a season, and also of productivity between seasons. For I. fuliginator, we demonstrate a population decline since 1998 and how this links with productivity, which is affected by temperature. A delayed mean emergence date in recent years is also shown.
A main point of interest is the focus on the two temporal scales at which perhaps most animal populations vary: in the short-term, a population is seldom truly closed within a single season, and in the long-term (between seasons) it never is. Hence our models may serve as a template for a general description of population dynamics in many species. This includes rare species with limited data sets, for which there is a general lack of population dynamic models, yet conservation actions may greatly benefit from this kind of models.

Keywords: beetle - endangered - Iberodorcadion fuliginator - integrated population model - multi-scale population dynamics - population model

Urban gardens are important for human well-being, biodiversity and other ecosystem functions. Biodiversity-promoting initiatives would benefit from their owners being aware of the state of biodiversity in their gardens. We examined whether garden owners' perceptions match actual biodiversity in their gardens and whether perceptions are influenced by the owners' ecological knowledge. We used a structured interview to assess the motivations and biodiversity knowledge of owners of 33 domestic gardens in the city of Basel (Switzerland) and related them to a survey of native plants and several groups of ground-dwelling invertebrates in their gardens. Owners showed different priorities, with promotion of habitat for biodiversity, receiving, on average, higher scores than cultivation, recreation and garden designing. Owners prioritizing biodiversity promotion had gardens with high habitat richness. The garden owners' perceptions of both native plant and overall invertebrate diversity were not correlated with actual diversity data for native plants and ground-dwelling invertebrates. The perceptions of the abundance of invertebrate groups by garden owners with good biodiversity knowledge were not more accurate than those from owners with less knowledge. Despite their willingness, many owners do not know all the opportunities to promote biodiversity. Initiatives to further biodiversity-friendly gardening should thus transfer knowledge.

Keywords: ants - beetles - biodiversity - ecological knowledge - gastropods - millipedes - private domestic gardens - spiders - urbanization - woodlice

Urbanization is occurring around the globe, changing environmental conditions and influencing biodiversity and ecosystem functions. Urban domestic gardens represent a small-grained mosaic of diverse habitats for numerous species. The challenging conditions in urban gardens support species possessing certain traits, and exclude other species. Functional diversity is therefore often altered in urban gardens. By using a multi-taxa approach focused on native grassland plants and ground-dwelling invertebrates with overall low mobility (snails, slugs, spiders, millipedes, woodlice, ants, rove beetles), we examined the effects of urbanization (distance to city center, percentage of sealed area) and garden characteristics on functional dispersion, functional evenness, habitat preferences and body size. We conducted a field survey in 35 domestic gardens along a rural–urban gradient in Basel, Switzerland. The various groups showed different responses to urbanization. Functional dispersion of native grassland plants decreased with increasing distance to the city center, while functional dispersion of ants decreased with increasing percentage of sealed area. Functional evenness of ants increased with increasing distance to the city center and that of rove beetles decreased with increasing percentage of sealed area. Contrary to our expectation, in rove beetles, the proportion of generalists decreased with increasing percentage of sealed area in the surroundings, and the proportion of species preferring dry conditions increased with increasing distance to the city center. Body size of species increased with distance to city center for slugs, spiders, millipedes, ants, and rove beetles. Local garden characteristics had few effects on functional diversity and habitat preferences of the groups examined. Our study supports the importance of using multi-taxa approaches when examining effects of environmental change on biodiversity. Considering only a single group may result in misleading findings for overall biodiversity. The ground-dwelling invertebrates investigated may be affected in different ways from the more often-studied flying pollinators or birds.

Urbanisation is increasing globally and is considered to be a main driver of environmental change. Urbanisation-related factors include reduced habitat size and increased spatial isolation of the remaining habitats. As a consequence, the dynamics of plant and animal populations may change, which in turn might influence the quality and quantity of plant resources. Thus, urbanisation has the potential to disturb plant-animal interactions such as herbivory or galling. In the urban-rural setting of Basel (Switzerland), we aimed to assess whether the degree of urbanisation and forest size influence plant-galling infestation rates and leaf damage by mining and chewing arthropods on three tree species (sycamore, beech, and ash). We recorded species-specific responses to the degree of urbanisation and forest size. Gall infestation rate on sycamore leaves was affected by urbanisation but not by forest size. In contrast, gall infestation rates of beech gall midges responded sensitively to increasing urbanisation and decreasing forest size. The total leaf area damage caused by mining and chewing arthropods on sycamore was influenced by urbanisation and increased with increasing forest size. Leaf area damage by miners in beech tended to be affected by the degree of urbanisation, but not in ash. Urbanisation and forest size have the potential to alter herbivorous insect abundances. However, the effects depend on tree species and herbivore guild.

Keywords: urbanisation - forest size - arthropods - insects - herbivory - galls - parasitoid - chewing - mining

Urbanisation is an important driver of environmental change and has the potential to alter the functioning of ecosystem processes. In urban forests, a key ecosystem process is litter decomposition, which is driven by the litter quality and composition of litter fauna. We examined whether the degree of urbanisation and forest size influence litter decomposition rates by the mesofauna in Basel (Switzerland). In order to assess the impact of the litter mesofauna on decomposition rates, we exposed litterbags with three mesh sizes (100__m, 2_mm, and 4_mm) filled with a mixture of Acer pseudoplatanus, Fagus sylvatica, and Fraxinus excelsior litter for a period of 9 months in 17 forests of different size located in areas with different degrees of urbanisation. We recovered the litterbags after 3, 6, and 9 months, extracted the fauna and assessed the decomposition rates. We found that litter decomposition rates were negatively affected by the degree of urbanisation after 6 months, but not impacted by forest size. In terms of litter fauna, oribatid mites and Collembola were differently affected by urbanisation. Oribatid mites were most frequent in forests in moderately urbanised areas, whereas Collembola were more abundant in forests in highly urbanised areas. Abundances of Acari and Oribatida were lowest in medium-sized forests, while the abundance of Collembola was highest in large forests. Collembola species composition did not shift with urbanisation. Considering Collembola traits, species with globular bodies were most abundant in forests of medium-size and situated in low urbanised areas, whereas species with an eudaphic life form tended to be less abundant in small forests. We showed that urbanisation and forest size have the potential to impact litter fauna abundance and species with certain morphological and life form traits, which may alter the important ecosystem service of litter decomposition.

Keywords: Acari - oribatid mites - collembola - species composition - traits - urban ecology

A single specimen of Anotylus politus was captured in Riehen (BS) in 2014. This is the first record of the species in Switzerland.

Keywords: Anotylus politus - Coleoptera - faunistics - new record - Staphylinidae - Switzerland

Successful action in conservation calls for close exchange and effective feedback between science and practitioners at all levels. However, many examples and experiences indicate that this mutual exchange does not function optimally nor according to requirements. From the authors' point of view, there is a need for a new “bridging” in conservation in order to optimise the transfer of evidence-based research results into practice and, vice versa, of practical requirements into science. Based on an analysis of the current challenges and causes in this context, this paper derives stakeholder-specific solutions to achieve a new bridging in conservation and presents them for discussion. In addition, it presents four best-practice examples. Conservation science must take greater account of practical requirements in conservation. Similarly, applied research addressing these requirements must gain more recognition by the scientific community. At the same time, the discussion is hoped to prompt con- servation practitioners to base their actions more strongly on evidence and to seek cooperation with the scientific community even more actively.

Keywords: conservation practice - evidence - conservation research - centre of competence - research funding - academic training

The invasive box-tree moth Cydalima perspectalis causes damage to horticultural box trees (Buxus spp.) in private gardens and parks in Europe and defoliation of large areas of European native box trees Buxus sempervirens, which grow in the understorey of deciduous forests. In some parts of their distribution area, wild native box trees are infected by the box rust Puccinia buxi, a fungus which does not occur in the native range of C. perspectalis. We examined whether the infection of P. buxi deters grazing by C. perspectalis in 31 wild box-tree stands in forests in north-western Switzerland and south-western Germany. On average, 82.4% of the box trees were infested by P. buxi (among-site variation 20%–100%), or 18.5% of their leaves. Linear mixed-effect (LME) models revealed that the percentage of rust-infected leaves was influenced by the local box-tree density and the slope aspect of the forest site. 9.5% of the leaves showed grazing damage by C. perspectalis. LME showed that the percentage of leaves with grazing damage was affected by the elevation of the site and the percentage of rust-infected leaves. The effect of box rust infection on food choice and larval performance (survival and growth rate) was examined in two experiments. In food-choice tests, larvae of C. perspectalis did not show any preference for uninfected or rust-infected box_tree leaves and consumed similar amounts of leaf tissue of either type. However, when larvae were reared on leaves with three different degrees of P. buxi-infection (and uninfected leaves as control), both survival and growth rate decreased with increasing degree of rust infection. This indicates that larval performance of C. perspectalis is reduced by the box rust. In the case of an outbreak of C. perspectalis, however, larvae may indiscriminately defoliate wild box trees.

Keywords: box-tree moth - food choice - herbivory - host plant - larval performance - pest species

Invasive plant species can significantly affect native biodiversity and ecosystem functioning. Even though the majority of ecosystems have more than 50% of the plant biomass belowground, most studies investigating the effects of invasive species on plant diversity focus on the aboveground vegetation. DNA-based methods allow the determination of belowground plant structures. Using these techniques, we examined potential effects of the annual invasive plant Impatiens glandulifera on both the above- and belowground plant species richness and composition in mixed deciduous forests in Northwestern Switzerland. We established 24 plots in three forest areas invaded by I. glandulifera and in three adjacent forest areas, which were not yet invaded. In each plot, we determined plant species richness and abundance in the aboveground vegetation, and collected soil samples at depths of 0–10_cm and 11–20_cm to determine belowground plant species richness. We extracted DNA from fine roots in the soil samples and applied the FAFLP technique (fluorescent amplified fragment length polymorphism) for two different regions of the chloroplast DNA (trnL-trnF intergenic spacer and P6 loop). We established a reference library for all plant species occurring in the study areas to identify the species present in mixed-root samples. Our results showed that I. glandulifera caused shifts in both the above- and belowground plant species composition. Plant species richness was reduced by 30% aboveground in invaded plots, but not belowground in the same plots. Many geophytes and woody species were found belowground but not aboveground in invaded plots. Root biomass was reduced by 35–55% in invaded plots, most probably due to allelopathic compounds released by the invasive plant into the soil. Our field survey shows that above- and belowground plant communities respond differently to the invasion of an annual plant species, and that the invasive species can negatively affect forest ecosystem functions, by reducing root biomass and altering plant species richness and composition.

Keywords: biological invasions - fluorescent amplified fragment length polymorphism (FAFLP) - Impatiens glandulifera - mixed root samples - species identification - trnL intron

Limestone cliffs in the Jura Mountains harbour species-rich plant and animal communities including rare species. Sport climbing has recently increased in popularity in this habitat and several studies have reported damage to cliff biodiversity. However, so far how damage levels vary with climbing intensity has not been investigated. We evaluated the effects of climbing intensity on the diversity of vascular plants and land snails in 35 limestone cliff sectors in the Northern Swiss Jura Mountains. Mixed-effects models were used to examine whether species richness of plants and land snails differ between cliff sectors with low and high climbing intensity and unclimbed cliff sectors (controls) taking into account potential influences of cliff characteristics (aspect, cliff height, rock microtopography). At the cliff base, the best fit model revealed that plant species richness was affected by climbing intensity and cliff aspect. Plant species richness was reduced by 12.2% and 13.1%, respectively, in cliff sectors with low and high climbing intensity compared to unclimbed cliff sectors. On the cliff face, plant species richness was only influenced by climbing intensity (species richness reduction by 24.3% and 28.1%). Combining data from cliff base, face and plateau, the best fit model revealed that land snail species richness was only affected by climbing intensity (species richness reduction by 2.0% and 13.7%). In both organism groups, species composition was increasingly altered by increasing climbing intensity. Our study provides evidence that even low climbing intensity reduces cliff biodiversity and that damage becomes more pronounced with increasing climbing intensity.

Urbanisation is increasing worldwide and is regarded a major driver of environmental change altering local species assemblages in urban green areas. Forests are one of the most frequent habitat types in urban landscapes harbouring many native species and providing important ecosystem services. By using a multi-taxa approach covering a range of trophic ranks, we examined the influence of degree of urbanisation and forest size on the species richness and functional diversity of plants, and ground surface-active ants and spiders. We conducted field surveys in twenty-six forests in the urban region of Basel, Switzerland. We found that a species’ response to urbanisation varied depending on trophic rank, habitat specificity and the diversity indices used. In plants, species richness decreased with degree of urbanisation, whereas that of both arthropod groups was not affected. However, ants and spiders at higher trophic rank showed greater shifts in species composition with increasing degree of urbanisation, and the percentage of forest specialists in both arthropod groups increased with forest size. Local abiotic site characteristics were also crucial for plant species diversity and species composition, while the structural diversity of both leaf litter and vegetation was important for the diversity of ants and spiders. Our results highlight that even small urban forests can harbour a considerable biodiversity including habitat specialists. Nonetheless, urbanisation directly and indirectly caused major shifts in species composition. Therefore, special consideration needs to be given to vulnerable species, including those with special habitat requirements. Locally adapted management practices could be a step forward to enhance habitat quality in a way to maximize diversity of forest species and thus ensure forest ecosystem functioning; albeit large-scale factors also remain important.

Conservation programs increasingly involve the reintroduction of animals which otherwise would not recolon- ize restored habitats. We assessed the long-term success of a project in which the Blue-winged grasshopper, Oedipoda caerulescens (L., 1758), was reintroduced to a nature reserve in Northwestern Switzerland, an alluvial gravel area where the species went extinct in the 1960s. In summer 1995, we released 110 individuals (50 fe- males and 60 males) and 204 individuals (101 females and 103 males) into two restored gravel patches with sparse vegetation. We used a transect count technique to assess the population size of O. caerulescens in the years 1995–2004 and 2015–2016 and recorded the area occupied by the species. At both release sites, the popu- lations persisted and increased significantly in size. Individuals that followed a newly created corridor estab- lished four new subpopulations. Seven years after reintroduction, O. caerulescens had reached a high abun- dance around the release sites and in the four colonized patches, indicating a successful project. At the same time, the dispersal corridor became increasingly overgrown by dense vegetation. Surveys 20 and 21 yr after introduction showed that the abundance of the Blue-winged grasshopper had strongly declined in the estab- lished subpopulations and moderately in the original release sites, owing to natural succession of the habitat and lack of disturbances, which reduced the area suitable for the species by 59%. Our study shows that reintro- ductions are unlikely to succeed without integration of long-term habitat management (in the present case maintenance of open ground).

Keywords: habitat restoration - propagule size - reintroduction - succession

• The specialized cliff biota is increasingly disturbed by recreational activities.
• We used land snails as indicator group for assessing the impact of sport climbing.
• Rock climbing reduces the diversity and abundance of land snails living on cliffs.

Exposed limestone cliffs in the Swiss Jura Mountains harbour a diverse gastropod community with some rare species. Sport climbing has recently increased in popularity on these cliffs. We examined the effects of sport climbing and microtopographical features of rock faces on terrestrial gastropods by assessing species diversity and abundance on climbing routes and in unclimbed areas of seven isolated cliffs in the Northern Swiss Jura Mountains. We considered exclusively living individuals resting attached to rock faces. In total, 19 gastropod species were recorded. Six of them were specialized rock-dwelling species, whose individuals spend their entire life on rock faces, feeding on algae and lichens. Plots along climbing routes harboured fewer species of rock-dwelling snails as well as other gastropod species (usually living in the leaf litter layer at the cliffs’ base) than plots in unclimbed control areas. Similarly, both the density of individuals and frequency of occurrence in plots were reduced in both groups of snails on climbing routes. The complexity of the rock surface had little influence on the species richness and abundance of gastropods. Pyramidula pusilla, the species with the smallest shell and a preference to rest underneath overhangs, was less affected by sport climbing than snail species with larger shells and a preference to rest on exposed smooth rock surface. Our findings indicate land snail diversity and abundance are suitable indicators for impact assessment in rocky habitats. Future management plans and actions should therefore not only rely on plants; they ought to consider also gastropods and other invertebrates. Any management plan should include a comprehensive information campaign to show the potential impact of intensive sport climbing on the specialized flora and fauna with the aim of educating the climbers and increasing their compliance with such measures.

Keywords: biodiversity - climbing - disturbance - gastropod - impact assessment

Invasions by alien plants significantly affect native biodiversity and ecosystem functioning. We conducted a 5-year field experiment to investigate potential effects of the annual invasive plant Impatiens glandulifera on both the native above-ground vegetation and the soil seed bank in a deciduous forest in Switzerland. Eight years after the establishment of I. glandulifera, we set up plots in patches invaded by the alien plant, in plots from which the invasive plant had been manually removed and in plots which were not yet colonized by the invasive plant. We examined plant species richness, diversity and plant species composition in the above-ground vegetation and soil seed bank in all plots one year and five years after the initiation of the experiment. The 36 plots (3 plot types × 6 replicates × 2 sites) were equally distributed over two forest sites. Neither the native above-ground vegetation nor the soil seed bank was influenced by the presence of I. glandulifera one year after the start of the field experiment. After five years, however, plant species richness of both the above-ground vegetation and the soil seed bank was reduced by 25% and 30%, respectively, in plots invaded by the alien plant compared to plots from which I. glandulifera had been removed or uninvaded plots. Furthermore, plots invaded by the alien plant had a lower total seedling density (reduction by 60%) and an altered plant species composition in the soil seed bank compared to control plots. Our field experiment indicates that negative effects of the annual invasive plant on the native above-ground vegetation and soil seed bank of deciduous forests become visible with a delay of several years.

Keywords: annual invasive plant species - disturbance - Impatiens glandulifera - temperate deciduous forest - time-dependent

Environmental changes associated with urbanisation can affect the functioning of ecosystem processes. In cities, forests are among the most frequent types of green areas and provide a wide range of ecosystem services including air cleaning, decomposition of leaf litter and recreation. The European beech (Fagus sylvatica) is a frequent and widespread deciduous tree in temperate forests in Central Europe. In this study, we examined the effects of urbanisation on decomposition processes of F. sylvatica leaves in different-sized forests in the urban region of Basel, Switzerland. We used standardised litterbags (mesh size: 2 mm) with F. sylvatica leaves to assess the impact of degree of urbanisation (indicated by the percentage cover of sealed area in the surroundings) and forest size on the early stage of leaf litter decomposition and seasonal microbial activity. We found combined effects of degree of urbanisation and forest size on the decomposition rate of leaf litter (k_litter). Large forests showed the highest k_litter in areas with sparse settlements and the lowest k_litter in densely settled areas, whereas the opposite pattern was recorded for small and medium-sized forests. This indicates that abiotic and biotic forest characteristics of forests of similar size differently influenced k_litter depending on the degree of urbanisation. Moisture content of litter was the best predictor of microbial activity, followed by forest size. We assume that factors acting at the landscape scale such as the degree of urbanisation might be too coarse to detect any differences in microbial activity. Our results revealed that even small urban forests contribute to this important ecosystem function. As decomposers are at the bottom of the food chain, management actions that support the biological activity in soil might be also beneficial for species at higher trophic ranks.

Keywords: decomposition rate - forest area - leaf chemical characteristics - microbial activity - plant diversity - temperate deciduous forests

Die «Erinnerungen an Pioniere des Schweizerischen Nationalparks» sind ein Beitrag zur Geschichte des Schweizerischen Nationalparks, insbesondere zu dessen Forschungsgeschichte. Dem Ansatz der Oral History folgend erinnern sich heute lebende Personen an Persönlichkeiten, welche die Forschung im Nationalpark zum Teil über Jahrzehnte hinweg geprägt haben und deren Forschungsergebnisse auch heute noch wichtige Grundlagen für weitere Projekte bilden. Denn die Langzeitforschung, das Erfassen der natürlichen Veränderungen in einer vom Menschen weitgehend unberührten Landschaft, ist ein zentrales Anliegen der Forschung im Nationalpark.
Die Erinnerungen sind zum Teil sehr persönlich geprägt, deshalb aber nicht weniger wertvoll als rein biografische Fakten. Sie beschreiben die damaligen Rahmenbedingungen, geben Einblicke in die Motivation für die intensive Beschäftigung mit der Natur im Nationalpark und zeigen auf, dass hinter den publizierten Forschungsergebnissen immer auch Individuen stehen – Menschen mit ihrem besonderen Charakter, mit ihren Vorlieben und Abneigungen, mit ihren Ecken und Kanten.

Habitat fragmentation is a major driver of biodiversity loss, but observed effects vary and may depend on the group examined. Time since fragmentation may explain some differences between taxonomical groups, as some species and thus species composition respond with a delay to changes in their environment. Impacts of drivers of global change may thus be underestimated in short-term studies. In our study we experimentally fragmented nutrient-poor dry calcareous grasslands and studied the response of species richness, individual density and species composition of various groups of invertebrates (gastropods, ants, ground beetles, rove beetles, orthoptera, spiders, woodlice) in 12 small (1.5 m * 1.5 m) and 12 large (4.5 m * 4.5 m) fragments and their corresponding control plots after 7 years. We further examined responses to fragmentation in relation to body size and habitat preferences. Responses to fragmentation varied between taxonomical groups. While spider species richness and individual density were lower in fragments, the opposite was true for an orthopteran species and woodlice. Species composition and ß-diversity differed between fragments and control plots for some groups. However, the interaction treatment*plot size was rarely significant. Species with high occupancy rates in undisturbed control plots responded more negatively to the fragmentation, while species with large body size were relatively more abundant in fragments in some groups. No effect of the fragmentation was found for ants, which may have the longest lag times because of long-lived colonies. However, relationships between abundance and the species’ preferences for environmental factors affected by edge effects indicate that ant diversity too may be affected in the longer-term. Our results show the importance of considering different groups in conservation management in times of widespread fragmentation of landscapes. While species richness may respond slowly, changes in abundance related to habitat preferences or morphology may allow insights into likely long-term changes.

Understanding how invasive plants modify symbiotic interactions between ectomycorrhizal (EM) fungi and native host trees is a central goal in invasion biology. We examined the effect of the annual invasive plant Impatiens glandulifera on the EM association and performance of Fagus sylvatica saplings in a controlled field experiment at three sites in a deciduous forest in Switzerland. A total of 1188 one-year-old F. sylvatica saplings were planted either in plots invaded by I. glandulifera, in plots from which the invasive plant had been manually removed or in plots which were not yet colonized by the invasive plant. The 54 (3 × 18) plots were equally distributed over three sites. Saplings, including their full root systems were harvested after 3, 6 and 15 months. Exudates of the invasive plant were extracted from resin bags buried in the soil during the seedling, flowering and senescent stage of I. glandulifera. EM colonization on F. sylvatica saplings growing in invaded plot was 33% lower after 3 months and 66% lower after 15 months than saplings growing in plots from which I. glandulifera had been removed and in uninvaded plots. Survival and biomass of saplings were reduced by 16% and 30% after 15 months in plots invaded by I. glandulifera. Analysis of the internal transcribed spacer region of fungal rDNA (ITS) showed that the number of EM species was highly correlated with the number of EM morphotypes, indicating that the latter can be considered as a surrogate for EM species richness on roots of F. sylvatica saplings. EM morphotype richness on saplings was 32% lower after 15 months in invaded plots as compared to control plots. Chemical analysis revealed a high amount of naphthoquinones in plots with I. glandulifera suggesting that this putative allelochemical can be responsible for the reduction in both EM colonization and morphotype richness. Our findings demonstrate the negative impact of an annual invasive plant on the ectomycorrhizal symbiosis and performance of native F. sylvatica saplings.

Keywords: allelopathy - deciduous forest - disturbance - naphthoquinones - plant–soil feedback - resin bag

As global climate change warms the Southern Ocean, wild king penguins (Aptenodytes patagonicus) may face drastic population declines in the future. Moreover, the captive breeding programme in Europe is currently unsustainable and it is thus imperative to determine what is required for the successful breeding of king penguins. A questionnaire was used to assess the husbandry practices and breeding success of 12 American and European zoos. Overall, a positive relationship was found between yearly egg productivity and density of king penguins held in enclosures in different zoos. All zoos examined showed male-biased adult sex ratios. Yearly egg productivity was negatively related to the deviation from an even sex ratio. Mean hatching success was greater in zoos performing outside walks with king penguins than in those that did not. Based on records over 40 years, the population of the sustainably breeding Basel Zoo in Switzerland was modelled using stage-based matrix models to gain an insight into its breeding success. Years of medium colony size (density of 0.25 to 0.38 individuals per m2) displayed a larger growth rate than years with high or low colony size, and years with equal sex ratios showed a higher growth rate than those with male-biased or female-biased sex ratios. The results suggest zoological institutions should focus on increasing density and strive toward equal sex ratios within king penguin populations to maximise breeding success. Where possible, adding outside walks should also be taken into consideration.

Keywords: Aptenodytes patagonicus - captive breeding - density - matrix model - sex ratio

Questions
Does the recent change from traditional to sprinkler irrigation result in alterations in the surrounding landscape of species-rich hay meadows in an arid Swiss mountain region? Are landscape composition and landscape heterogeneity important determinants of plant diversity in these meadows?

Location
Southwestern Switzerland.

Methods
We surveyed vascular plant species in six traditionally and six sprinkler-irrigated hay meadows. Plant species were divided into grassland specialists and generalists. Individual landscape traits were assessed in circular areas with radii of 50 and 100 m around each meadow in a field survey. Aerial photographs were used to measure the percentage area covered by different habitat types in the present and prior to the installation of sprinklers at the same spatial scale as in the field surveys. The potential effects of irrigation technique and present-day landscape features on the plant diversity and species composition of hay meadows were examined with GLM and NMDS.

Results
Landscape composition was more diverse for traditionally than for sprinkler-irrigated meadows, but did not differ prior to the installation of sprinklers. Total plant species richness and the number of specialists were negatively affected by the distance to the closest haystack. Generalists were positively influenced by a variety of different small-scale landscape traits in the surroundings, whereas the percentage area covered by woodland had a negative effect. Finally, hay meadows irrigated with sprinklers had an increased number of generalist plant species.

Conclusions
This study showed that the small-scale surroundings, and to some extent the type of irrigation, are important for the conservation of plant diversity of these meadows. Furthermore, the study suggests that the installation of sprinklers was associated with a homogenization of the landscape, which facilitates land use. Extensive management should be promoted by compensation payments for farmers to prevent intensification.

Keywords: generalists - grassland specialists - landscape traits - land-use change - semi-natural grassland - small-scale landscape - Valais (Switzerland) - water management

In a seasonal environment, the suitable time window for females to reproduce is restricted by both environmental conditions and the availability of males. In simultaneous hermaphrodites, which are female and male at the same time, selection on a trait that is solely beneficial for one sexual function cannot occur independently. Therefore, it is assumed that the optimal time window for reproduction is a compromise between the two sexual functions in simultaneous hermaphrodites, mediated by environmental conditions. We examined seasonal patterns of reproduction and the resulting paternity in a natural population of the simultaneously hermaphroditic land snail Arianta arbustorum. Adult and premature individuals (snails in a short protandric phase) were collected on four occasions over the entire active season. The snails were allowed to deposit eggs after which we assessed the level of paternity in their hatched offspring. Individuals mated throughout the reproductive season, whereas egg production – the major task of the female function – was restricted to the first half of the season. Snails collected in autumn were allowed to hibernate under laboratory conditions. As a result, we found that premature individuals began to mate late in the reproductive season, but did not start to produce eggs before emerging from hibernation. Our results demonstrate a temporal shift of reproductive activities; the egg production and oviposition occur mainly in the first half of the season, while sperm production and mating occur over the entire season. In subadult and adult snails, sperm obtained from several partners in the second part of the reproductive season are stored during hibernation for the fertilization of eggs in the successive years. These results extend our understanding of the influence of both natural and sexual selection on reproductive strategies in hermaphrodites.

Keywords: gastropod - hibernation - male function - multiple paternity - sperm storage

Dieses Buch stellt in einem interdisziplinären Ansatz die Bedeutung von Wasserfällen mit ihren ökologischen und soziokulturellen Qualitäten vor. Es zeigt, welche Pflanzen- und Tierarten im Spritzbereich von Wasserfällen vorkommen. Touristische und kunsthistorische Bedeutungen von Wasserfällen werden beschrieben und quantifiziert sowie Aspekte, welche die Gesundheit der Menschen fördern, skizziert. Zudem wird eine neue Methode zur Erfassung der landschaftsästhetischen Qualitäten vorgestellt. Abschließend werden Empfehlungen zur Beurteilung der Erhaltungswürdigkeit von Wasserfällen aufgeführt.
Das Buch präsentiert wertvolle Grundlagen zur Diskussion über die Zukunft der Wasserfälle in der Schweiz.

Invasive plants can disrupt associations between soil organisms and native trees which may result in altered ecosystem functions, both reduced biodiversity and timber production. We examined the effect of the invasive annual plant Impatiens glandulifera on the arbuscular mycorrhiza (AM) symbiosis and performance of Acer pseudoplatanus saplings at three different levels of disturbance in a controlled field experiment in a deciduous forest in Switzerland. A total of 1125 one-year-old A. pseudoplatanus saplings were planted either in plots invaded by I. glandulifera, in plots from which the invasive plant had been manually removed or in plots which were not yet colonised by the invasive plant. The 45 (3 × 15) plots were equally distributed over three forest areas which were differently affected by a wind throw 12 years prior to the experiment. Saplings including their full root systems were harvested after 3, 6 and 15 months. I. glandulifera reduced AM colonisation on A. pseudoplatanus saplings by 30–43%. Reduction in AM colonisation did not differ between harvesting time and was not affected by the level of forest disturbance. Saplings growing in invaded plots also showed a reduced root biomass and survival rate compared to saplings in the other plots. Increases in soil moisture, soil pH, available phosphorus and microbial activity found in plots invaded by I. glandulifera did not affect AM colonisation and performance of saplings. Our findings demonstrate that the spread of the invasive I. glandulifera in mixed deciduous forests negatively affects the symbiotic association between AM fungi and A. pseudoplatanus saplings and thus forest regeneration.

Keywords: Acer pseudoplatanus - disturbance - forest ecosystem - Impatiens glandulifera - plant–soil feedback - survival

In arid regions, irrigation is required to secure agricultural production including the production of hay. The Valais, a dry inner alpine valley of Switzerland, has a long tradition of meadow irrigation. However, in the 20th century irrigation was stopped on marginal, poorly accessible areas usually accompanied by the entire abandonment of these meadows. The aim of this study was to examine the consequences of land-use abandonment resulting from the cessation of irrigation for the biodiversity of species-rich hay meadows in the Valais. We compared soil characteristics and species richness and composition, habitat specificity and functional traits of plants and gastropods of three serial stages of succession (each five hay meadows, early abandoned meadows and young forests). Soil moisture was lower in young forests than in the other two stages. Soil nitrogen content decreased following abandonment, which was due to the cessation of fertilization. The three successional stages did not differ in plant species richness but harboured distinct plant communities. Gastropod richness increased with progressive succession and species composition of hay meadows differed from those of the two other stages. The proportion of grassland (plants) and open-land (gastropods) species decreased following abandonment. Furthermore, meadow abandonment led to an increase in the height of non-woody plant species, a later start of seed shedding, a change in the type of plant reproduction and an increase in the shell size of gastropods. In conclusion, this study showed that extensive land-use, which is strongly linked to irrigation, is required for the characteristic species-rich hay meadows of this arid mountain region.

Keywords: land-use change - grassland succession - plants - gastropods - soil characteristics - Valais (Switzerland)

Landschnecken spielen als Zersetzer von totem Pflanzenmaterial eine wichtige Rolle im Stoffkreislauf der Natur. Sie werden aber kaum wahrgenommen, weil viele von ihnen ein Gehäuse von nur wenigen Millimetern Grösse haben. Die Autorinnen und Autoren untersuchten anhand umfangreicher Feldaufnahmen die Vielfalt der Landschnecken in den unterschiedlichsten Lebensräumen der Biosfera Val Müstair. Als Ergebnis wird nicht nur eine Zustandsbeschreibung präsentiert, sondern es werden auch natürliche Faktoren und menschliche Einflüsse vorgestellt, welche die Vielfalt und Artzusammensetzung dieser Tiergruppe beeinflussen. Schnecken gelten als ausgezeichnete Zeigerorganismen und erlauben Rückschlüsse auf den Zustand der Lebensräume in der Biosfera Val Müstair.

In promiscuous species with sperm storage, males are expected to show a preference for mating with virgin and young females to reduce the risk of sperm competition. In the simultaneous hermaphrodite land snail Arianta arbustorum, sperm production precedes egg production by 2–4 weeks, resulting in a short period of protandric hermaphroditism before shell growth is completed. In natural populations, copulating pairs involving individuals which have not yet completed shell growth (virgins) have been observed. We ran a series of mate-choice experiments to examine whether virgin and nonvirgin (experienced) individuals of A. arbustorum discriminate between virgin and nonvirgin mating partners. We also assessed the number of sperm delivered to partners with different mating status. Neither virgin nor nonvirgin snails showed any preference for mating with a virgin partner. In all test situations mating was random and the number of sperm delivered was not adjusted to the mating status of the partner. Mating success was mainly determined by the activity of the individual. The random mating pattern does not imply random fertilization of eggs because the presence of a sperm-digesting organ and the morphology of the sperm storage organ allow a selective storage and use of sperm in A. arbustorum.

Keywords: mate choice - mate recognition - mating behavior - preference - sexual selection

Traditional management practices are suggested to maintain species-rich grasslands. In the Valais, an arid region of Switzerland, hay meadows are traditionally irrigated using open water channels. However, in the past decades this irrigation technique has been increasingly replaced by sprinkler irrigation, which is assumed to result in a more homogeneous water distribution than open water channels. This study examined whether the change in irrigation technique affected the small-scale distribution of plants and soil characteristics in hay meadows in the Valais. Three plots consisting of 13 subplots of increasing size (0.1 × 0.1 to 6.4 × 6.4 m) were installed in six traditionally and six sprinkler-irrigated meadows. In all subplots, plant species richness and soil characteristics [moisture, pH, total organic nitrogen, organic matter content (SOM), total and plant available phosphorus] were recorded. The type of irrigation technique did not affect the shape of the plant species–area relationship. In none of the meadows did the species area–curves reach the asymptote within the range of plot sizes examined. Mantel r statistics showed that spatial autocorrelation in the soil characteristics examined was low and their small-scale distributions were not influenced by the irrigation technique except for soil pH and SOM. Our results indicate a pronounced small-scale heterogeneity in the distribution of plant species and soil characteristics for both types of irrigation technique. This can partly be explained by the fact that sprinklers distribute the water less homogeneously than commonly assumed. As applied in the Valais, sprinkler irrigation does not reduce the spatial heterogeneity and hence biodiversity of hay meadows.

Keywords: semi-natural grassland - water management - land use change - species–area relationship - spatial autocorrelation - Valais (Switzerland)

Sperm morphology can be highly variable among species, but less is known about patterns of population differentiation within species. Sperm morphology is under strong sexual selection, may evolve rapidly, and often co-varies with other reproductive traits that differ between populations. We investigated variation in sperm morphology in the simultaneous hermaphrodite land snail Arianta arbustorum in relation to parasitic mite infection. Variation in total sperm length and sperm head length was assessed in 23 populations sampled across the distributional range of the species in Central and Northern Europe. We found a pronounced variation in total sperm length among the populations studied, with a difference of 11.0% of total sperm length between the shortest and longest population means. Differences among populations explained 62.9% of the variance in total sperm length, differences among individual snails within population 23.4% and differences within individual snail 13.7%. Mantel tests showed that interpopulation differences in total sperm length increased significantly with geographical distance between populations. A minimal adequate model revealed that parasitic infection had a positive effect and longitude a negative effect on total sperm length. Thus, independent of the population examined, mite-infected individuals of A._arbustorum produced larger sperm than uninfected snails and total sperm length decreased from west to east. Sperm head length also varied among populations, but it was not influenced by any of the factors examined. In a subsample of 12 populations restricted to the mountains of Switzerland (elevational range 440–2485_m_a.s.l.), total sperm length decreased with increasing elevation. Our results suggest that selection pressures acting among populations may differ from those acting within. Stabilizing selection might be a possible mechanism for producing the reduced variation observed in sperm length within a population.

Keywords: Arianta arbustorum - elevation - geographical variation - parasite - sperm length

Invasive plants can disturb interactions between soil organisms and native plants and thereby alter ecosystem functions and/or reduce local biodiversity. Collembola and Acari are the most abundant microarthropods in the leaf litter and soil playing a key role in the decomposition of organic material and nutrient cycling. We designed a field experiment to examine the potential effects of the annual invasive plant Impatiens glandulifera on species diversity, abundance and community composition of Collembola and Acari in leaf litter and soil in a deciduous forest in Switzerland. Leaf litter and soil samples were obtained from plots invaded by I. glandulifera since 6 years, from plots in which the invasive plant had been removed for 4 years and from plots which were not yet colonized by the invasive plant. The 45 leaf litter and soil samples were equally distributed over three forest areas, which were differently affected by a wind throw 12 years prior to sampling representing a natural gradient of disturbance. Collembola species richness and abundance in the leaf litter and soil samples were not affected by the presence of the invasive plant. However, the species composition of Collembola was altered in plots with I. glandulifera. The abundance of leaf-litter dwelling Acari was increased in invaded plots compared to the two other plot types. Furthermore, the presence of the invasive plant shifted the composition of Acari individuals belonging to different groups. Our field experiment demonstrates that an annual invasive plant can affect microarthropods which are important for nutrient cycling in various ecosystems.

Keywords: alien plant - beech forests - microarthropods - soil characteristics

The box-tree pyralid Cydalima perspectalis (Walker 1859) (Lepidoptera: Pyralidae), native to Eastern Asia, is a newly introduced species causing severe damage to box-trees (Buxus sp.) in private and public gardens as well as in semi-natural box-tree forests in Central Europe. It is so far not known whether different box-tree subspecies (or varieties) are similarly affected by this invasive moth. In a choice experiment offering branches of five different box-tree varieties as oviposition sites, we found a preference of female moths for laying their egg clusters on the variety ‘Rotundifolia’, while other varieties were less frequently considered. The preference for ‘Rotundifolia’, the variety with the largest leaves in the tests, remained when intervariety differences in foliar area (mean leaf size × number of leaves) were taken into account. Feeding larvae on leaves of either of the five box-tree varieties revealed a significant effect of the seasonal generation of C. perspectalis on the growth rate of individuals but no influence of the box-tree variety. Larvae from the spring generation show the highest growth rate, those from the summer generation a moderate and those from the autumn generation the lowest growth rate. The moths used in the experiments may belong to the 10th to 12th generation present in Europe. The time elapsed since their introduction may be too short for an optimal adaptation to the partly novel diet encountered by the invasive moth.

Keywords: Buxus - Cydalima perspectalis - invasive species - larval development - oviposition preference

The maintenance of traditional management practices is essential for the conservation of the biodiversity of semi-natural grasslands including species-rich hay meadows. In the canton Valais (Switzerland), hay meadows are traditionally irrigated using open water channels. However, since the 1980s, this labour intensive irrigation technique has been increasingly replaced by sprinkler irrigation. This study examined whether the different irrigation techniques (traditional vs. sprinkler) influence the local biodiversity of species-rich hay meadows. In particular, the diversity and composition of plant and gastropod species of eight traditionally irrigated meadows were compared with those of eight sprinkler-irrigated meadows. It was also assessed whether the species of either meadow type differed in functional traits. A high plant species richness was found in the meadows investigated. The study showed that the diversity and composition of plant and gastropod species of hay meadows were not affected by the change in irrigation technique 8–18 years ago. However, a lower grass/forb-ratio was observed in traditionally than in sprinkler-irrigated meadows. Furthermore, irrigation technique affected the leaf distribution and the onset of seed shedding in plants. Thus, the change in the irrigation technique altered only some aspects of biodiversity. Therefore, irrigation system alone does not represent the major factor affecting the biodiversity of hay meadows investigated.

Keywords: semi-natural grassland - water management - land-use change - functional traits - plants - gastropods

Der Bestand der Barrenringelnatter ist in der Schweiz im 20. Jahrhundert stark zurückgegangen, insbesondere im Mittelland. Deshalb wird die Barrenringelnatter auf der Roten Liste der gefährdeten Arten als «verletzlich» geführt. Als Folge der veränderten Landnutzung und der Entwässerung von Feuchtgebieten hat die Fläche ihrer Lebensräume abgenommen.
Zudem führt die zunehmende Zersiedelung zu einer Fragmentierung der Lebensräume. Fehlender Genfluss zwischen Teilpopulationen kann zur genetischen Verarmung führen, die ein erhöhtes Aussterberisiko für die betroffenen Populationen bedeutet.
Im vorliegenden Band wird die genetische Populationsstruktur der Ringelnatter mithilfe molekulargenetischer Methoden in drei Gebieten untersucht: in einem intensiv genutzten Landwirtschaftsgebiet, in einer ehemaligen Auenlandschaft und in einem ländlichen Tal in den Berner Alpen. Die Ergebnisse werden auf einer lokalen und einer regionalen Ebene diskutiert. Der Einfluss des Paarungsmusters der Schlangen auf die Populationsstruktur wird ebenfalls behandelt. Zudem wird eine mögliche genetische Vermischung der einheimischen Ringelnattern mit eingeführten, standortfremden Schlangen untersucht. Aufgrund der Ergebnisse werden allgemeine Schlussfolgerungen sowie Empfehlungen für den praktischen Naturschutz abgeleitet

Sperm length varies considerably, both between and within species, but the evolutionary implications of this variation are poorly understood. Sexual selection on sperm length requires a significant additive genetic variance, but few studies have actually measured this. Stylommatophoran gastropods have extraordinarily long sperm. However, the extent of intraspecific variation has rarely been examined. Here we present the first estimates of heritability of sperm length in the land snail Arianta arbustorum using two complementary approaches (one-parent–offspring regression and full-sibling split design). We also examined whether sperm length is influenced by the shell size of the snail and estimated heritability of shell size. Sperm delivered by the same individuals in 2–4 matings over two reproductive seasons did not differ in length, indicating a high repeatability of this trait. Offspring of 10 families were kept at three temperatures (11, 15 and 20°C) to examine the influence of different environmental conditions on sperm length and adult shell breadth. Independent of shell breadth, sperm length was affected by temperature but not by family of origin (the variance component associated with family was not significantly different from zero), while adult shell breadth was influenced by temperature and family of origin. Higher temperatures resulted in shorter sperm, but larger shells. The heritability of sperm length derived from the two different approaches (one-parent–offspring regression: h2 ± SE = 0.52 ± 0.55; full-sibling split design: H2 ± SE = _0.19 ± 0.28) suggests relatively little genetic variation in this trait in the studied population. In contrast, the heritability of adult shell breadth indicates a strong genetic effect (mother–offspring regression, h2 ± SE = 0.90 ± 0.33). The heritability (h2 ± SE) of adult shell breadth obtained from the father–offspring regression was 0.18 ± 0.42, i.e. five times smaller than that of the mother–offspring regression, suggesting a maternal effect on shell size.

The European Alps harbour a unique and species-rich biodiversity, which is increasingly impacted by habitat fragmentation through land-use changes, urbanization and expanding transport infrastructure. In this study, we identified the 50 most important questions relating to the maintenance and restoration of an ecological continuum – the connectedness of ecological processes across many scales including trophic relationship and disturbance processes and hydro-ecological flows in the European Alps. We initiated and implemented a trans-national priority setting exercise, inviting 48 institutions including researchers, conservation practitioners, NGOs, policymakers and administrators from the Alpine region. The exercise was composed of an initial call for pertinent questions, a first online evaluation of the received questions and a final discussion and selection process during a joint workshop. The participating institutions generated 484 initial questions, which were condensed to the 50 most important questions by 16 workshop participants. We suggest new approaches in tackling the issue of an ecological continuum in the Alps by analysing and classifying the characteristics of the resulting questions in a non-prioritized form as well as in a visual conceptualisation of the inter-dependencies among these questions. This priority setting exercise will support research and funding institutions in channelling their capacities and resources towards questions that need to be urgently addressed in order to facilitate significant progress in biodiversity conservation in the European Alps.

This study documents the spread of the invasive clam Corbicula spp. in Switzerland since its first record in the River Rhine in 1995. Clams were newly recorded in several Swiss lowland lakes whose interconnecting rivers have not yet been colonized. We present evidence for separate introductions of an identical haplotype of Corbicula fluminea into five lakes in Switzerland in the years 2003–2010 based on the mitochondrial DNA-sequence of the COI in specimens sampled. This suggests passive dispersal of the clam by human activities and/or waterfowl. All but one of the 72 genetically analysed individuals were assigned to a single haplotype FW5 and to the species name C. fluminea. Recent records of specimens, which were not genetically analysed, displayed all the shell morphology of C. fluminea, confirming the dominance of this clam in Swiss rivers and lakes.

Keywords: alien species - DNA sequencing - COI - invasive species - range expansion - Corbicula - Switzerland

Males can enhance their reproductive success through mating with multiple females. For females, however, one mating is usually sufficient to inseminate all of their ova. Females may benefit from multiple mating by producing genetically more diverse offspring, and by having the opportunity to choose sperm of the genetically most compatible male. We used five microsatellite loci to investigate the occurrence and frequency of multiple paternity in 11 clutches of the grass snake (Natrix natrix) in Switzerland. Using a very conservative estimate (program GERUD), two or more fathers were found in 27% of the clutches. However, based on the maximum likelihood estimate (program COLONY), multiple paternity occurred in 91% of the clutches with 2-5 contributing males per female. This is the first investigation demonstrating multiple paternity in a European natricine, with a frequency similar to those found in new world natricines.

Keywords: COLONY - GERUD - microsatellite DNA - Natricinae - paternity analysis

Question: Is illegal garden waste dumping in mixed deciduous forests a source for establishment of non-native plants in deciduous forests?
Location: Northwestern Switzerland.
Methods: We quantified the amount of illegally dumped garden waste at 20 sites over 1 yr and compared the soil conditions, species richness and abundance of plants in the ground vegetation at disposal sites with those at 20 control sites in urban deciduous forests.
Results: We found that illegal garden waste dumping frequently occurs in urban forests. At single sites, 0.1–12.5 m3 (mean: 2.6 m3) garden waste was dumped per month, resulting in a total annual amount of 2.2–35.8 m3 (mean: 17.8 m3) waste deposited. Thirty-seven of the 163 plant species recorded were not native to Switzerland. All 37 non-native species were recorded in waste disposal sites, but only three of them in control sites. Thus, garden waste dumping sites harboured a larger number of non-native species than control sites, but the two groups of sites did not differ in number of native species. The species composition also differed between disposal and control sites: larger proportions of species typical of disturbed habitats, more therophytes and species with autochorous seed dispersal were recorded in disposal sites than in control sites.
Conclusions: We provide evidence that numerous non-native horticultural plant species escape from dumping sites and colonize forests. There is an urgent need to increase awareness of garden owners concerning problems associated with illegal garden waste dumping.

Invasive species of the knotweed complex (Fallopia sp.) have repeatedly been shown to decrease diversity of native local biota. While effects on plant species richness are well established, effects on invertebrate and in particular gastropod species richness are less well understood. We recorded cover of plant species and diversity and abundance of gastropodspecies in four plots (1 m × 1 m) with Fallopia japonica and compared these to paired control plots without F. japonica at 15 sites along the river Birs (Switzerland) in early summer (June) and autumn (September). Knotweed and control plots did not differ in site characteristics and soil parameters.
Average plant species richness in F. japonica plots was 50% lower compared to control plots. This reduction was significant for woody species as well as for herbaceous species. However, species richness of early flowering annuals did not differ significantly. Among the species most affected by knotweed were hop (Humulus lupulus) and European spindle tree (Euonymus europaeus) but also stand-forming species such as nettle (Urtica dioica) or ground elder (Aegopodium podagraria).
Average snail species richness was significantly reduced in F. japonica plots. The reduction was pronounced in large (≥5 mm shell size) and long-lived (>2 years) snail species but not in slugs or small and short-lived snails. For example, large snails such as the Roman snail (Helix pomatia, -85%) or the red-listed speciesBradybaena fruticum (-93%), showed reduced abundances in F. japonica compared to control plots. In contrast, the red-listed but small Vertigo pusilla (+92%) had higher abundances in F. japoinca plots. Principal component analyses revealed little overlap in plant communities or community composition of large snail species between F. japonica and control plots. Taken together, knotweedinvasion decreased the cover of most plantspecies and abundance of large and long-lived gastropods.

Keywords: biodiversity - exotic - Fallopia - invasive - Reynoutria - riparian habitat

Temperature can be a limiting factor on parasite development. Riccardoella limacum, a haematophagous mite, lives in the mantle cavity of helicid land snails. The prevalence of infection by R. limacum in populations of the land snail Arianta arbustorum is highly variable (0-78%) in Switzerland. However, parasitic mites do not occur in host populations at altitudes of 1290 m or higher. It has been hypothesized that the host's hibernation period might be too long at high elevations for mites and their eggs to survive. To test this hypothesis, we experimentally infected snails and allowed them to hibernate at 4°C for periods of 4-7 months. Winter survival of host snails was negatively affected by R. limacum. The intensity of mite infection decreased with increasing hibernation duration. Another experiment with shorter recording intervals revealed that mites do not leave the host when it buries in the soil at the beginning of hibernation. The number of mites decreased after 24 days of hibernation, whereas the number of eggs attached to the lung tissue remained constant throughout hibernation. Thus, R. limacum survives the winter in the egg stage in the host. Low temperature at high altitudes may limit the occurrence of R. limacum.

Exposed limestone cliffs in central Europe harbor a highly divers flora with many rare and endangered species. During the past few decades, there has been increasing recreational use of these cliffs, which has caused local environmental disturbances. Successful restoration strategies hinge on identifying critical limitations. We examined the composition of aboveground forest vegetation and density and species composition of seeds in the soil seed bank at the base of four limestone cliffs in mixed deciduous forests that are intensively disturbed by human trampling and at four undisturbed cliffs in the Jura Mountains in northwestern Switzerland. We found that long-term human trampling reduced total aboveground vegetation cover at the base of cliffs and caused a significant shift in the plant-species composition. Compared with undisturbed cliffs, total seed density was lower in disturbed cliffs. Human trampling also altered the species composition of seeds in the soil seed bank. Seeds of unintentionally introduced, stress-tolerant, and ruderal species dominated the soil seed bank at the base of disturbed cliffs. Our findings indicate that a restoration of degraded cliff bases from the existing soil seed bank would result in a substantial change of the original unique plant composition. Active seed transfer, or seed flux from adjacent undisturbed forest areas, is essential for restoration success.

Keywords: deciduous forest - recreational disturbance - restoration - species composition - sport climbing

Herbivores are known to decrease plant species diversity in ecosystems with low productivity. Limestone pavements are low-productive habitats harboring specialized communities of cyanobacteria, and endo- and epilithic lichens exposed to extreme temperature and humidity fluctuations. Pavements of the Great Alvar (Öland, Sweden) are covered by free-living cyanobacteria giving the rock surface a dark color. Based on cyanobacterial abundance along the edges, two types of cracks intersecting the pavements have been described: Type one with abundant cyanobacteria and type two without cyanobacteria resulting in light-colored edges. Erosion and different lengths of inundation by melt water have been suggested to cause the conspicuous differences in community composition and hence color between cracks. We hypothesized that this pattern results from the grazing activity of the cyanobacteria- and lichen-feeding snail Chondrina clienta, which reduces cyanobacterial cover along light-colored cracks and facilitates endolithic lichens. Three dark and three light-colored cracks were investigated at each of three localities. Crack characteristics (i.e., aspect, width, depth and erosion) and snail density were assessed at the crack level. Cyanobacterial cover and lichen diversity were recorded in 1-cm sections, sampled every 5 cm along eight 160-cm-long transects per crack. Model selection was applied to estimate effects of snail density and distance from crack edges on cyanobacterial abundance and lichen diversity. Crack characteristics explained no differences in cyanobacterial cover or lichen diversity. However, cyanobacterial cover decreased towards the edges of cracks with high snail densities. A transplant experiment supported the correlational evidence. The abundant cyanobacterial cover on pieces of stone placed close to cracks with high snail densities was completely grazed within 19 months. By contrast, cyanobacteria recolonized initially completely grazed pieces of stone when fixed near cracks without snails. Abundance and diversity of endolithic lichens increased along cracks with high compared to low snail densities but decreased in epilithic lichens and lichens with cyanobacterial symbionts. However, the presence of the gastropod herbivore decreased overall lichen diversity. Comparing presence-absence matrices with null models revealed that species co-occurred less frequently than expected. Taken together, we provide evidence that herbivory indirectly released endolithic lichens from competition for light by reducing cyanobacterial cover.

Keywords: bioweathering - cyanobacteria - epilithic lichen - herbivory - spatial pattern

Different mechanisms of reproductive isolation were examined in the simultaneously hermaphroditic land snail Arianta arbustorum. Snails from two geographically isolated populations in the Swiss Alps were allowed to copulate with both a homotypic (individual from the same population) and a heterotypic (individual from the other population) partner (in half of the pairs in reversed order). Control snails mated twice with a homotypic partner. In the first mating, successful copulations occurred in a lower frequency in heterotypic pairs (55.6%) than in homotypic pairs (82.9%). Heterotypic pairs that eventually copulated showed more breaks during courtship than homotypic pairs. However, neither the number of eggs produced nor their hatching success was influenced by the type of mating partner. In the second mating, the sequence of different partners had an effect on the proportion of successful copulations in snails from one geographical population. Snails that copulated first with a homotypic partner remated more frequently with a homotypic partner than snails that copulated first with a heterotypic partner. Paternity analyses of progeny of snails that mated twice indicate no influence of the origin of the mating partner. The proportion of hatchlings sired by the second mate (P2) averaged 0.39, indicating a slight first-mate advantage. However, highly skewed paternity patterns were found in the progeny of 44.4% of the double-mated snails. Genetic analyses also revealed a low frequency of self-fertilization (3.7%). These findings indicate the presence of partial precopulatory isolation between two distant snail populations, although reproductive compatibility is still maintained.

Organisms provide some of the most sensitive indicators of climate change and evolutionary responses are becoming apparent in species with short generation times. Large datasets on genetic polymorphism that can provide an historical benchmark against which to test for recent evolutionary responses are very rare, but an exception is found in the brown-lipped banded snail (Cepaea nemoralis). This species is sensitive to its thermal environment and exhibits several polymorphisms of shell colour and banding pattern affecting shell albedo in the majority of populations within its native range in Europe. We tested for evolutionary changes in shell albedo that might have been driven by the warming of the climate in Europe over the last half century by compiling an historical dataset for 6,515 native populations of C. nemoralis and comparing this with new data on nearly 3,000 populations. The new data were sampled mainly in 2009 through the Evolution MegaLab, a citizen science project that engaged thousands of volunteers in 15 countries throughout Europe in the biggest such exercise ever undertaken. A known geographic cline in the frequency of the colour phenotype with the highest albedo (yellow) was shown to have persisted and a difference in colour frequency between woodland and more open habitats was confirmed, but there was no general increase in the frequency of yellow shells. This may have been because snails adapted to a warming climate through behavioural thermoregulation. By contrast, we detected an unexpected decrease in the frequency of Unbanded shells and an increase in the Mid-banded morph. Neither of these evolutionary changes appears to be a direct response to climate change, indicating that the influence of other selective agents, possibly related to changing predation pressure and habitat change with effects on micro-climate.

Classical sexual selection theory assumes that the reproductive success of females is limited by the resources available for egg production, while the reproductive success of males is determined by the number of mates (Bateman's principle). It has been suggested that the optimal mating rates should also diverge between gender functions within individuals of simultaneous hermaphrodites. We assessed determinants of mating success and female and male reproductive success in individuals of the simultaneous hermaphrodite land snail Arianta arbustorum. We videorecorded the behaviour of individually tagged snails kept in groups of six animals over one reproductive period (58 days) and assigned the genotyped hatchlings to the female and male function of individual parents. We found considerable interindividual variation in the activity of snails, which is a combined measure of time spent crawling, feeding and digging. The snails mated between zero and three times. Mating success, which is equal to the female and male function in simultaneous hermaphrodites with reciprocal copulation, was mainly determined by the activity of an individual. We found that female reproductive success (number of hatchlings emerging from the eggs laid by the focal snail) was positively correlated with male reproductive success (number of hatchlings sired by the focal snail) and that both were determined by the individual's activity. Furthermore, both female and male reproductive success of an individual were influenced positively by the snail's degree of genetic heterozygosity and negatively by shell size. Our results challenge the trade-off assumption of sex allocation theory in simultaneous hermaphrodites.

Keywords: Arianta arbustorum - gastropod - mating success - multiple mating - paternity - reproductive success - sex allocation - simultaneous hermaphrodite

In species with multiple mating and long-term sperm storage, males are expected to show a preference for mating with virgin and young females to reduce the risk of sperm competition. In various simultaneous hermaphrodite land snail species, sperm production precedes egg production by 2-4 weeks, resulting in a short period of protandric hermaphroditism before shell growth is completed. In a natural population, we collected copulating pairs of the simultaneous hermaphrodite land snail Arianta arbustorum (L., 1758) consisting either of two adults, of two subadults, or of one adult and one subadult snail, and determined the paternity of their hatchlings that emerged from subsequently deposited eggs. Adult snails used sperm received from subadult mating partners for egg fertilization in the same frequency as sperm from adults, indicating that subadult and adult snails do not differ in male function. Furthermore, an unfinished shell is not a reliable indicator for virginity, because 35% of the subadult individuals had already sperm stored from previous mating(s). Compared with adults, young individuals exhibited a lower risk of sperm competition, indicated by a higher last mate sperm precedence. However, subadult snails produced fewer eggs than adult snails, counteracting the evolutionary advantage of preferring a young partner with low sperm competition risk.

Mating frequency has important implications for patterns of sexual selection and sexual conflict, and hence for issues such as the maintenance of genetic diversity and speciation. We assessed the level of multiple paternity and sperm utilization patterns in four natural populations of the simultaneous hermaphrodite land snail Arianta arbustorum using four polymorphic microsatellite loci. A total of 1088 offspring from 26 wild-caught snails were genotyped to determine the number of fathers siring each brood and paternity skew in succeeding clutches. Multiple paternity was detected in the offspring of all 26 mother snails examined with the contribution of two to six fathers. The four populations examined differed in the level of multiple paternity. Snails in the population with the highest density of adults showed the highest level of multiple paternity, whereas snails in the population with the lowest density exhibited the lowest value of multiple paternity. Highly skewed paternity patterns were found in the progeny of 15 (57.7%) of the 26 mother snails. The number and identity of fathers siring the offspring of single mothers also varied among successive clutches. Furthermore, genetic analyses indicate a low level of self-fertilization in one of the four populations.

Keywords: Arianta arbustorum - Gastropoda - mating frequency - paternity analysis - population density - self-fertilization

Parasite transmission fundamentally affects the epidemiology of host–parasite systems, and is considered to be a key element in the epidemiological modelling of infectious diseases. Recent research has stressed the importance of detailed disease-specific variables involved in the transmission process. Riccardoella limacum is a hematophagous mite living in the mantle cavity of terrestrial gastropods. In this study, we experimentally examined whether the transmission success of R. limacum is affected by the contact frequency, parasite load and/or behaviour of the land snail Arianta arbustorum, a common host of R. limacum. In the experiment the transmission success was mainly affected by physical contacts among snails and slightly influenced by parasite intensity of the infected snail. Using these results we developed two different transmission models based on contact frequencies and transmission probability among host snails. As parameters for the models we used life-history data from three natural A. arbustorum populations with different population densities. Data on contact frequencies of video-recorded snail groups were used to fit the density response of the contact function, assuming either a linear relationship (model 1) or a second-degree polynomial relationship based on the ideal gas model of animal encounter (model 2). We calculated transmission coefficients (β), basic reproductive ratios (R₀) and host threshold population densities for parasite persistence in the three A. arbustorum populations. We found higher transmission coefficients (β) and larger R₀-values in model 1 than in model 2. Furthermore, the host population with the highest density showed larger R₀-values (16.47–22.59) compared to populations with intermediate (2.71–7.45) or low population density (0.75–4.10). Host threshold population density for parasite persistence ranged from 0.35 to 2.72 snails per m². Our results show that the integration of the disease-relevant biology of the organisms concerned may improve models of host–parasite dynamics.

Keywords: parasite transmission - epidemiology - basic reproductive ratio -transmission model - Riccardoella limacum - Arianta arbustorum

Was bedeutet Biodiversität und warum ist sie wichtig für die Menschen? Bruno Baur erklärt grundlegende Aspekte der Biodiversität und erläutert Prozesse, die zu Veränderungen in der Vielfalt des Lebens auf unserem Planeten führen. Ein verständlicher Einstieg für Studierende der Biologie, Ökologie, Geografie, Raumplanung, Umwelt-, Agrar- und Forstwissenschaften, Ressourcenmanagement, Ökonomie, Politologie und Ethik.

ISBN 978-3-8252-3325-9

Rivers are among the most endangered ecosystems of the world with dramatically decreasing biodiversity. Rehabilitation programmes aiming at restoration of riverine ecosystems rely on the recolonisation of native macroinvertebrates from refuges. We examined whether a relatively natural remnant of the former river Rhine (Altrhein) harbours a higher richness of benthic macroinvertebrates than two sites of the modified Rhine with artificial and semi-natural embankments near Basel. All three sites were bimonthly sampled between May 2007 and May 2008 using three techniques: Kick and Sweep, drifting animals collected from pieces of stone turned by hand, and animals collected from stone surfaces. Taxa richness was higher in the Altrhein than in the two sampling sites in the river Rhine, but it was mainly a result of the large number of individuals sampled at this site. Despite 17% of taxa recorded were alien, the three sampling sites differed neither in the number of alien taxa nor in their abundances. However, lower percentages of both alien taxa and individuals were recorded in the Altrhein than at the other two sites in the Rhine. Indicator value analysis showed that the macroinvertebrate community of the Altrhein maintains several native and specific taxa. Multivariate analyses supported the separation of the communities collected at different sampling sites and also the uniqueness of the community in the Altrhein. The observed patterns, however, strongly depended on the sampling method applied, thereby calling the attention to the application of standard sampling methods and also to the restriction of result comparisons on projects using identical sampling methodology. Our study shows that the remnant of the former river Rhine serves as a refuge for macroinvertebrates which may facilitate future restoration of the river embankment.

Keywords: alien taxa - richness - conservation value - macroinvertebrates - river Rhine

Life-history traits in terrestrial gastropods may be influenced by both abiotic and biotic factors. This study examines the effects of soil type and adult size (shell volume) on mating propensity and female and male reproductive output (number and mass of eggs, number of sperm delivered and spermatophore mass) in individuals of the simultaneous hermaphrodite land snail Arianta arbustorum from two populations kept both on calcium-(Ca-)rich and Ca-poor soil. Snails from the two populations differed in adult size, relative shell growth, mating propensity and egg size. Furthermore, in both populations the number of egg batches deposited, egg size and spermatophore size scaled allometrically with shell volume, but not the total number of eggs produced and number of sperm delivered. Independent of population and shell size, the type of soil on which the snails were maintained influenced mating propensity, the total number of eggs produced and the mass of the albumen gland (another measure of female reproductive output). The mating propensity was higher and the total number of eggs produced was larger in snails kept on Ca-poor soil than in individuals reared on Ca-rich soil. This surprising finding could be explained by the fact that the Ca-poor soil used in the experiment still contained enough Ca to allow reproduction, and that the snails ingested Ca through the food consumed (lettuce grown on Ca-rich soil was available ad libitum). Moreover, the Ca-rich soil could contain minerals or (unknown) substances which discourage reproduction in A. arbustorum. Our study highlights the complexities faced when interpreting differences in the life history of gastropods. Explaining interpopulational differences in life-history patterns requires not only the understanding of the influence of snail origin, but also an understanding of the effects of shell size, substratum type (soil type), food and local climate.

Keywords: Arianta arbustorum - calcium availability - egg size - reproductive allocation - simultaneous hermaphrodite - sperm number

Urban forests are popular recreation areas in Europe. Several of these temperate broad-leaved forests also have a high conservation value due to sustainable management over many centuries. Recreational activities, particularly the use of fireplaces, can cause extensive damage to soil, ground vegetation, shrubs, and trees. Firewood collection depletes woody debris, leading to a loss of habitat for specialized organisms. We examined the effects of fireplace use on forest vegetation and the amount of woody debris by comparing disturbed and control plots in suburban forests in northwestern Switzerland. At frequently used fireplaces, we found reduced species densities in the ground vegetation and shrub layer and changes in plant species composition due to human trampling within an area of 150–200 m². Picnicking and grilling also reduced the height and changed the age structure of shrubs and young trees. The amount of woody debris was lower in disturbed plots than in control plots. Pieces of wood with a diameter of 0.6–7.6 cm were preferentially collected by fireplace users. The reduction in woody debris volume extended up to a distance of 16 m from the fire ring, covering an area of 800 m² at each picnic site. In order to preserve the ecological integrity of urban forests and to maintain their attractiveness as important recreation areas, we suggest depositing logging residues to be used as firewood and to restrict visitor movements near picnic sites.

Keywords: picnicking - grilling - outdoor recreation - firewood collection - human trampling - nature conservation - sustainable forest management

Six novel polymorphic microsatellite loci are presented for the grass snake (Natrix natrix), a species with declining populations in many regions. The number of alleles per locus ranged from two to seven. Four dice snake (Natrix tessellata) microsatellites were polymorphic in the grass snake with three to four alleles. At two loci, the expected heterozygosity differed significantly from observed heterozygosity. Cross-amplification of the grass snake markers in the dice snake showed two polymorphic microsatellites with two and four alleles.

Keywords: conservation - dice snake - grass snake - microsatellites - Natrix natrix - Natrix tessellata

Central European forests are generally multifunctional; the same forest areas are used for timber production and recreation. In frequently visited areas damage to trees can be observed. We developed a method to estimate the actual reduction in timber value due to recreation-induced damage. The method was tested in two suburban (oak-hornbeam and beech) forests sustainably maintained by a selective management system and with free access in northwestern Switzerland. Considering the total forest areas, 9.4% of oak trees and 23.0% of beech trees were damaged by recreational activities. The resulting reduction in timber value averaged 19 and 53 (sic) ha(-1) a(-1) in the two forests. The annual reduction in timber value due to recreation-induced damage can account for up to 16% of the total proceeds. The monetary benefits of forest recreation in these areas, however, by far exceed the damage to trees.

Keywords: forest recreation - multifunctionality - tree damage - spatial distribution of damage

Understanding the effects of disturbance by human trampling on ecosystem processes is essential for themanagement of recreational areas. Discussions on recreational impacts are based either on data from trampling experiments or on field survey data from sites subjected to long-term recreational use, but rarely on a combination of both. We examined whether results from a short-term trampling experiment reflect the impact of long-term trampling around frequently used fire places. We compared short- and long-term effects of human trampling on above-ground forest vegetation and soil physical, chemical and microbial characteristics.We found both similarities and differences in short- and long-term trampling effects. Both short- and long-term trampling reduced plant cover, plant height and species density, though long-term effects were more pronounced than short-term effects. In both approaches, leaf litter biomass decreased, whereas soil density increased with trampling intensity. Other soil characteristics including soil moisture, total soil organic matter content and total organic nitrogen content were not or only marginally affected by short- and long-term trampling. Furthermore, soil microbial biomass and the activity of dehydrogenase did not change in both approaches. In contrast, the activity of b-glucosidase was only reduced by short-term trampling, whereas activity of phosphomonoesterase was reduced only by long-term trampling. Soil compaction was one factor reducing microbial activities at low and medium trampling intensities in our experiment and in the highly compacted area around the fire rings. We conclude that it could be problematic to use the results of short-term trampling experiments to predict general long-term trampling effects. Our results imply also that the restoration of degraded sites might be hampered by the low nutrient turnover resulting from the reduced litter layer and changes in enzyme activities, mitigating a successful re-establishment and growth of plants.

Keywords: fire places - long-term effects - outdoor recreation - short-term effects - soil enzyme activities - urban forest

Parasites can influence the population dynamics of their hosts by affecting life-history strategies and behavior. The hematophageous mite Riccardoella limacum lives in the lung cavity of terrestrial gastropods. We used correlational and experimental approaches to investigate the influence of parasite infection on the behavior and life-history traits of the simultaneously hermaphroditic land snail Arianta arbustorum, a common host of R. limacum. Naturally infected individuals of A. arbustorum, collected in the wild, showed a decreased activity compared with uninfected snails. The reproductive output, expressed as the number of eggs deposited in a reproductive season, was reduced in mite-infected hosts. However, the hatching success of the eggs laid by parasitized snails was slightly higher than that of uninfected individuals. We also examined winter survival in 361 adults of A. arbustorum collected from four natural populations. The prevalence of mite infection ranged from 44.8% to 70.1% in three populations (snails in the fourth population were not infected). Winter survival was reduced in infected snails in two out of three populations. Furthermore, experimentally infected snails from an uninfected population showed a reduced winter survival compared with control snails. Our results indicate that parasite pressure imposed by members of R. limacum may influence life history in A. arbustorum.

Keywords: terrestrial gastropod - reproduction - survival - life history

The route of transmission and host finding behaviour are fundamental components of a parasite's fitness. Riccardoella limacum, a haematophagous mite, lives in the mantle cavity of helicid land snails. To date it has been assumed that this parasitic mite is transmitted during courtship and mating of the host. Here we present experimental evidence for a new transmission route in the host snail Arianta arbustorum. Parasite-free snails were kept on soil on which previously infected host snails had been maintained for 6 weeks. R. limacum was successfully transmitted via soil without physical contact among hosts in 10 out of 22 (45.5%) cases. In a series of experiments we also examined the off-host locomotion of R. limacum on snail mucus and control substrates using an automated camera system. Parasitic mites showed a preference to move on fresh mucus. Our results support the hypothesis that R. limacum uses mucus trails to locate new hosts. These findings should be considered in commercial snail farming and when examining the epidemiology of wild populations.

Keywords: parasite transmission - host-finding - snail mucus - Arianta arbustorum - Riccardoella limacum

The recreational function of forests is highly relevant in urban areas. Picnicking and grilling are two of the most popular recreational activities in Swiss forests. While the density of official picnic sites with barbecue pits (number per ha) is similar in forests near large and small urban areas and in rural areas, the density of fire rings outside official picnic sites is especially high in forests that surround large urban areas. According to experts, the low concentration of barbecue pits and available firewood coupled with forest visitors seeking adventure and romanticism often lead to the creation of ´wildª fire rings. Recreational activities in the forest often lead to conflicts.Conflicts between recreation and hunting, in particular, seem to be pronounced in all areas of Switzerland. The disturbance of wildlife by recreationists is regarded as a major problem.In many places, direct and indirect management actions are implemented in order to reduce these conflicts.

Keywords: survey - forestry experts - outdoor recreation - picnicking - grilling -Switzerland

To examine the effect of habitat connectivity on the genetic differentiation in the frequently selling gastropod Chondrina avenacea we assessed RAPD profiles in 12 subpopulations from continuous cliffs and in 12 subpopulations from small, naturally fragmented cliffs in the Swiss Jura mountains. Subpopulations of C. avenacea on continuous cliffs showed a smaller number of polymorphic RAPD loci and a lower gene diversity (Nei's h = 0.049) than subpopulations on fragmented cliffs (h = 0.078). Genetic distance was not correlated with geographical distance between subpopulations. GST analysis indicated strong isolation effects. Neither the number of polymorphic loci nor Nei's h was correlated with local population density. Our analysis indicates that the local population structure of C. avenacea is a combined result of frequent self-fertilization, genetic drift and low dispersal. Similar findings have been reported in studies on spatial population structure of plants. We suggest that future management actions (selective tree cutting, and controlled access of sport climbers) should also consider small, isolated limestone cliffs to preserve the genetic diversity of C. avenacea.

Keywords: habitat connectivity - fragmentation - limestone cliffs - gastropods - RAPD

Livestock grazing is a common management practise in semi-natural grasslands in Central Europe. Different types of livestock (horses, cattle, sheep) and grazing intensity are known to affect the richness and composition of plant species. However, knowledge of grazing-dependent effects on invertebrates is limited. We examined the influence of horse, cattle and sheep grazing on the richness, abundance and composition of land snail species in 21 calcareous nutrient-poor grassland areas in the northwestern Jura Mountains, Switzerland. Grazing by different livestock species did not affect the species richness, abundance and species composition of land snails. Furthermore, the number of open-land species and the ratio of large- to small-sized snail species or individuals did not differ among the three pasture types. However, independent of livestock species, grazing intensity negatively influenced the snail fauna. Snail species richness, abundance and number of Red list species decreased with increasing grazing intensity. Grazing intensity also affected the occurrence of individual snail species (Truncatellina cylindrica, Cecilioides acicula, Candidula unifasciata and Trichia plebeia). To preserve the snail fauna in nutrient-poor grasslands, pastures can be stocked with horses, cattle or sheep. However, both maximum stocking rate (number of livestock units per hectare) and grazing duration (number of grazing days per year) must be carefully defined for the proper management of the pastures.

Keywords: pasture management - livestock species - grazing intensity - gastropods - Biodiversity

Alpine grasslands in the Southern Carpathian Mts, Romania, harbour an extraordinarily high diversity of plants and invertebrates, including Carpathic endemics. In the past decades, intensive sheep grazing has caused a dramatic decrease in biodiversity and even led to eroded soils at many places in the Carpathians. Because of limited food resources, sheep are increasingly forced to graze on steep slopes, which were formerly not grazed by livestock and are considered as local biodiversity hotspots. We examined species richness, abundance and number of endemic vascular plants and terrestrial gastropods on steep slopes that were either grazed by sheep or ungrazed by livestock in two areas of the Southern Carpathians. On calcareous soils in the Bucegi Mts, a total of 177 vascular plant and 19 gastropod species were recorded. Twelve plant species (6.8%) and three gastropod species (15.8%) were endemic to the Carpathians. Grazed sites had lower plant and gastropod species richness than ungrazed sites. Furthermore, grazed sites harboured fewer gastropod species endemic to the Carpathians than ungrazed sites. On acid soils in the Fagaras Mts, a total of 96 vascular plant and nine gastropod species were found. In this mountain area, however, grazed and ungrazed sites did not differ in species richness, abundance and number of endemic plant and gastropod species. Our findings confirm the high biodiversity of grasslands on steep slopes in the Southern Carpathian Mts and caution against increasing grazing pressure in these refuges for relic plants and gastropods as well as for other invertebrates.

Keywords: Alpine grassland - biodiversity - Bucegi Mts - Gastropoda - grazing - Fagaras Mts - vascular plants

Exposed limestone cliffs in the Swiss Jura Mountains harbour a diverse lichen community with some rare species. Sport climbing has recently increased in popularity on these cliffs. We examined the effect of sport climbing on calcicolous lichens by assessing species diversity and cover of lichens in climbed and unclimbed areas of 10 isolated cliffs in the northern Swiss Jura Mountains. We also investigated possible associations between lichens and lichen-feeding land snails on these cliffs. A total of 38 calcicolous lichen species, three bryophytes and one alga were found on the rock faces of 10 cliffs. Twenty lichen species (52.6%) were epilithic, 16(42.1%) endolithic and two (5.3%) foliose. Overall, the epilithic lichen species covered 8.3% of the rock surface, endolithic species 10.2%, and foliose species 0.03%. Climbed and unclimbed rock areas did not differ in total number of lichen species, species density (number of species per 100 cm ²) or total lichen cover. However, the frequency of occurrence of epilithic lichens was lower along climbing routes than in unclimbed areas. A multi-response permutation test showed that the lichen community composition of climbed areas differed from that of unclimbed areas. The dissimilarity of lichen communities between climbed and unclimbed areas increased with increasing climbing intensity on the focal route in climbed areas, but not with the age of the climbing route. Five of the 11 snail species recorded on the cliff faces were specialized lichen feeders. Plots along climbing routes harboured fewer snail species than plots in unclimbed areas. Total snail abundance was positively correlated with lichen species richness, but no correlation between snail species richness and lichen species richness was found. Our results indicate that frequent rock climbing can change the lichen community and reduce the snail community of limestone cliffs. A climbing-related reduction of snail abundance may also alter the lichen-herbivore interaction and indirectly change competitive interactions among lichen species.

Keywords: disturbance - Jura mountains - lichen - gastropod - rock climbing; - limestone cliff

A bursa tract diverticulum is widespread in the female part of the hermaphroditic reproductive system of stylommatophoran pulmonates. However, the ultrastructure of the diverticulum is unknown and there is only anecdotal evidence for a spermatophore-dissolving function for this organ. In the present study, we examined the ultrastructure of the diverticulum and investigated histological, histochemical and morphometric changes at different time intervals after mating in the simultaneously hermaphroditic land snail Arianta arbustorum. The diverticulum in this species of snail is a prominent organ, consisting of a luminal columnar epithelium surrounded by a thick layer of connective tissue. During mating, the diverticulum functions as the site of spermatophore uptake. Within the lumen of the diverticulum, the spermatophore wall is dissolved or at least partly broken down. The digested material is taken up by epithelial cells and accumulated in molluscan-specific cells of the connective tissue, the so-called rhogocytes. Subsequent to copulation, the total diameter of the diverticulum increases markedly, reaching a maximum size 12 hours after mating, while at the same time the thicknesses of the diverticulum wall and diverticulum epithelium decrease. The length of the diverticulum shows a positive allometry and a high phenotypic variation compared to snail size, which suggests that the diverticulum is under directional sexual selection. We propose that the diverticulum in A. arbustorum has evolved in response to selection pressures imposed by divergent evolutionary interests between male and female function.

Keywords: diverticulum - sexual conflict - sexual selection - sperm digestion - spermatophore

Recent changes in agriculture (intensification or abandonment) have resulted in a critical reduction of semi-natural grasslands in Eastern Europe. Subalpine semi-natural grasslands in Transylvania, Romania, harbour a high diversity of plants and invertebrates, including endemics, and are considered refugia for numerous threatened open-land species. We investigated effects of land abandonment by examining species richness, species abundance, proportion of open-land, endemic and threatened vascular plants, gastropods, and diurnal and nocturnal Lepidoptera in extensive hay meadows (initial stage), and three seral stages of succession (early stage of abandoned hay meadow, naturally growing birch forest, and mature forest) in the mountainous region of Baisoara in Transylvania. A total of 626 species (225 vascular plants, 16 gastropods, 68 diurnal and 317 nocturnal Lepidoptera) were found in the 16 study sites (four replicates per successional stage). The four taxonomic groups differed in their response to the abandonment of hay meadows. Each stage of succession harboured the maximum species richness for one taxonomic group: extensive hay meadows for vascular plants, abandoned hay meadows for diurnal Lepidoptera, birch forests for nocturnal Lepidoptera, and mature forests for gastropods. In all four taxonomic groups the complementarity of species composition increased with successional age, whereas the number of characteristic open-land species decreased with successional age. The four successional stages did not differ in proportion of red-listed plant and diurnal Lepidoptera species. In nocturnal Lepidoptera, however, the proportion of red-listed species increased with successional age. Furthermore, successional stages did not differ in number of plant species endemic to the Carpathians and Eastern Europe. Our results indicate the high conservation value of all stages of subalpine grassland succession for the indigenous biodiversity of Transylvania. To prevent losses of characteristic species, we suggest a rotational grassland management program that maintains different successional stages.

Keywords: land use change - grassland succession - Carpathic endemic - Eastern Europe

In many simultaneously hermaphroditic land snail species the sperm storage organ (spermatheca) is highly structured, suggesting that the female function might be able to influence offspring paternity. Physical properties of the sperm storage organ, including its initial size and sperm storage capacity may also affect fertilization patterns in multiply mated snails. We examined the structure, volume and tubule length of empty spermathecae in the land snail Arianta arbustorum and assessed differences in spermatheca size following a single copulation. The number of spermathecal tubules ranged from 2-7, but was not correlated with the volume of empty spermathecae. The volume of sperm stored in the spermatheca after a copulation was correlated with neither the number of spermathecal tubules nor copulation duration. Mean spermathecal volume more than doubled between two and thirty six hours after sperm uptake, but the length of spermathecal tubules did not change. Interestingly, the volume of sperm stored in the spermatheca seems not to be related to the size of the spermatophore and thus not to the number of sperm received (= allosperm). The amount of allosperm digested in the bursa copulatrix was highly variable and no significant relationship with the size of the spermatophore received was found. These findings suggest that numerical aspects of sperm transfer are less important in influencing fertilization success of sperm in A. arbustorum than properties of the female reproductive tract of the sperm receiver.

Keywords: Arianta arbustorum - sexual selection - simultaneous hermaphrodite - sperm storage - spermathecal morphology

Lichen growth and regeneration depend on the net photosynthetic production, the lateral allocation of products, on abiotic factors, competition and herbivory, and may therefore vary both in space and time (Hill 1981). Herbivores cause different damage to lichens in response to different thallus structure (surface toughness) and growth form, presence/absence of secondary compounds, and due to herbivore-specific differences in feeding (Lawrey 1984; Fröberg et al. 1993; Baur et al. 1994; Hesbacher et al. 1995). Regeneration of artificially damaged lichen tissue has been investigated in detail, for example in Xanthoria parietina (L.) Th. Fr. (Honegger 1996; Honegger et al. 1996). However, quantitative assessments of the regenerative capacity of thalli damaged by herbivores are so far lacking. Damage to lichens by grazing gastropods is made by highly specialized radulae and can therefore not be imitated by any mechanical treatment (Baur et al. 2000). Herbivory by snails also involves the production of saliva and mucus, which both could affect lichen regeneration.

Recent changes in agriculture (intensification or abandonment) have resulted in a critical reduction of steppe-like grasslands in Eastern Europe. These grasslands harbor an extraordinarily high diversity of plants and invertebrates, including endemics, and are considered refugia for numerous threatened open-land species. We examined species richness, and abundance, proportion of open-land, endemic and threatened vascular plants, gastropods, and diurnal and nocturnal Lepidoptera in six different vegetation types all originating from steppe-like grasslands in Transylvania, Romania. Vegetation types included extensively grazed pastures (initial stage), three seral stages of succession (early stage of abandoned grassland, abandoned grassland with shrubs, and mature forest), and two human-made grassland alterations, namely abandoned vineyards and Pinus plantations. A total of 852 species (291 vascular plants, 24 gastropods, 129 diurnal and 408 nocturnal Lepidoptera) were found in the 22 study sites. The four taxonomic groups differed in their response to the abandonment of steppe-like grassland, except that species richness of plants and diurnal Lepidoptera were positively correlated. The complementarity of species composition increased with successional age in all taxonomic groups examined. The number of characteristic open-land species decreased with successional age in plants and gastropods. All investigated vegetation types harbored threatened (red-listed) species. Endemic species were found in all vegetation types except mature forests and Pinus plantations. All Transylvanian endemics and the majority of threatened species found were open-land species. Extensively cultivated vineyards, which have been abandoned for two to three decades, also maintained high plant and invertebrate diversities, comparable to those of the corresponding stages of grassland succession. In contrast, Pinus plantations (a recent grassland alteration) have changed habitat quality and will have a devastating effect on the unique, indigenous diversity of these steppe-like grasslands as soon as the canopy closes. To prevent losses of characteristic species, we suggest a rotational grassland management program that maintains different seral stages. Succession to mature forest and additional Pinus plantations should be prevented.

Keywords: diurnal Lepidoptera - nocturnal Lepidoptera - endemic species - extinction - gastropods - habitat alteration - red-data species - succession - vascular plants

Questions: How does recreational disturbance (human trampling) affect soil characteristics, the performance of the understorey vegetation, and the density and species composition of the soil seed bank in Fagus sylvatica forests?
Location: Suburban forests near Basel, northwestern Switzerland.
Methods: We compared various soil characteristics and the performance of the understorey vegetation in six beech forest areas frequently disturbed by recreational activities with those in six undisturbed control areas, in spring 2003. In the same forest areas, the soil seed bank was investigated using the seedling emergence method. Samples were obtained from soil cores in January 2003.
Results: We found substantial changes in soil compaction, above-ground vegetation and in the soil seed bank due to recreational activities. In frequently visited areas, soil compaction was enhanced which caused a decrease in cover, height and species richness of both herb and shrub layers. Compared with control areas, the number of trampling-tolerant species of the seed bank was significantly higher in disturbed areas, and total species richness tended to be higher in disturbed than in control areas. Furthermore, the similarity in species composition between the above-ground vegetation and seed bank was significant lower in disturbed than in control areas.
Conclusions: The intensive use of suburban forests for recreational activities, mainly picnicking, affects the vegetation of natural beech forests. Our study indicates that a restoration of degraded forest areas from the soil seed bank would result in a substantial change of the vegetation composition.

Keywords: deciduous forest - human trampling - picnic site - restoration - soil compaction - species composition

Different species may respond differently to habitat fragmentation. Theory predicts that abundant generalist species should be less affected by fragmentation than specialist species. In ant communities, the most abundant species is often behaviourally dominant. Thus, habitat fragmentation could alter competitive interactions between the dominant ant species and the other species. We tested this hypothesis in a long-term grassland fragmentation experiment. Fragments of different size (20.25 and 2.25 m²) were isolated by a 5-m wide strip of frequently mown vegetation. Control plots were situated in adjacent undisturbed grassland. Ant density and species composition were assessed 3 and 6 years after initiation of the experimental fragmentation. The effect of the dominant ant species on the resource use of the other species was examined at natural sugar resources (aphids and extrafloral nectaries) and at artificial sugar baits. Lasius paralienus was the most abundant ant species (72% of nests) in the grasslands examined. Species richness and forager density in the other species decreased with increasing density of L. paralienus in fragments but not in control plots. The overall forager density of the other species was positively related to their habitat niche overlap with L. paralienus. The density of foragers of the other species at sugar resources was not affected by L. paralienus forager density. The experimental fragmentation resulted in an increase in natural sugar resources in fragments. This may have reduced the intensity of interspecific competition for sugar resources. Our study shows that the grassland fragmentation altered interactions between the dominant L. paralienus and the other ant species.

Keywords: community composition - dominance - Euphorbia cyparissias - Formicidae - nest density

The parasitic mite Riccardoella limacum sucks blood in the lung of its host, the land snail Arianta arbustorum. The infection of various host populations was examined in Switzerland. In a lowland snail population, prevalence of infection did not vary among seasons. However, intensity of mite infection in dissected individuals of A. arbustorum was high in autumn, but low in winter and spring when <= 100 mite eggs were found attached to the lung epithelium. A novel, non-invasive parasite screening method was used to estimate the number of mites on living host snails. An analysis of repeatability revealed that 92.9% of the snails were correctly classified as infected or non-infected with this non-invasive method. Prevalence of mite infection was examined in 997 adults of A. arbustorum from 11 natural populations distributed over an altitudinal gradient ranging 335-2360 m. No infected snails were found in 7 populations, while in the remaining 4 populations the prevalence of mite infection ranged 45.8-77.8%. Intensity of infection also differed among the 4 host populations. No geographic pattern in prevalence of infection was found. However, parasitic mites did not occur in snail populations situated at elevations of 1290 m or higher. A possible explanation for this finding could be that the host's hibernation period may be too long at high elevations for mites and their eggs to survive. At low elevations, other factors may affect the presence of R. limacum in the lung of A. arbustorum.

Keywords: terrestrial gastropod - mite - lung parasite - geographic variation - seasonal variation

Exposed cliffs of the Swiss Jura mountains harbour a highly diverse flora with many rare and endangered plant species. Many cliffs are frequently visited by rock climbers. We examined the impact of rock climbing on vascular plants in the lower part of four cliffs of the Gerstelflue (NW Switzerland) by comparing the vegetation of climbed and unclimbed areas. In climbed areas plant cover and species density were reduced. Similarly, the density of forbs and shrubs decreased, whereas the density of ferns tended to increase. In addition, rock climbing caused a significant shift in plant species composition and altered the proportions of different plant life forms. Rock climbing can be a threat to sensitive plants of the limestone cliff community.

Keywords: disturbance - Switzerland - vascular plants

Exposed cliffs in the northern Swiss Jura Mountains harbour a highly diverse flora with numerous endangered and relic plant species. On these cliffs, sport climbing is enjoying increasing popularity. We examined the ecological effects of sport climbing on vascular plants at the cliff base and on the cliff face by assessing plant cover and species density at various distances from frequently used climbing routes. Plant cover was significantly reduced at the base of climbing routes. Furthermore, species density (number of species per square metre) at the cliff base, as well as plant cover and species density at the cliff face, tended to increase with distance from the route. We also compared the vegetation of five frequently climbed cliffs with that of seven unclimbed cliffs. Climbing significantly altered the plant composition. Specialized rock species occurred less frequently on climbed cliffs than on unclimbed cliffs. Management plans and conservation actions are needed to preserve the threatened plant species on frequently climbed cliffs. Such plans should include the establishment of climbing-free protection areas on cliffs with a high number of specialized, relic plants and the protection of entire cliffs that are not yet climbed.

Keywords: disturbance - vegetation - Jura Mountains - rock climbing - limestone cliff

Theory predicts that at higher trophic levels species are especially vulnerable to habitat fragmentation due to small population size and dependence on particular prey species. Using aphids as model organism, we tested the hypothesis that herbivore abundance increases in fragmented habitats is a result of reduced predator and parasitoid densities. In a 3 year-study, we examined the population dynamics of aphids with respect to host plant abundance and ant nest density in experimentally fragmented calcareous grasslands at two sites in the northern Jura mountains. Fragments of different size (area: 20.25 m², 2.25 m² and 0.25 m²) were isolated by a 5 in wide strip of frequently mown vegetation and corresponding control plots were situated in the adjacent undisturbed grassland. Aphid density was higher in fragments than in control plots. This was a combined result of a higher frequency of aphid-infested plants and larger aphid colonies in fragments than in control plots. Furthermore, a larger proportion of aphid colonies was ant-attended in fragments than in control plots. Aphid colonies were also more frequently visited by ants in fragments than in control plots in one of the 3 years. Parasitoid pressure on aphids was not influenced by the experimental fragmentation. Neither were aphid species richness and diversity affected by the fragmentation. Our study shows that even small-scale habitat fragmentation can have profound effects on the abundance of herbivorous insects. The effect on aphid density was consistent over 3 years and two sites with slightly different aphid communities.

Keywords: habitat fragmentation - extrafloral nectaries - goldenrod aphids - plant-quality - species loss - ants - association - competition - subdivision - mutualists

The genetic differentiation of populations having colonized formerly unsuitable habitats after the Pleistocene glaciations depends to a great extent on the speed of expansion. Slow dispersers maintain their refugial diversity whereas fast dispersal leads to a reduction of diversity in the newly colonized areas. During the Pleistocene, almost the entire current range of the land snail Arianta arbustorum has repeatedly been covered with ice or been subjected to permafrost. Owing to the low potential for dispersal of land snails, slow (re)colonization of the wide range from southern refugia can be excluded. Alternatively, fast, passive dispersal from southern refugia or survival in and expansion from multiple refugia within the area subjected to permafrost may account for the current distribution. To distinguish between these scenarios we reconstructed a phylogeography based on the sequences of a fragment of the cytochrome oxidase I from 133 individuals collected at 45 localities and analysed the molecular variance. Seventy-five haplotypes were found that diverged on average at 7.52% of positions. This high degree of diversity suggests that A. arbustorum is an old species in which the population structure, isolation and the hermaphroditic nature have reduced the probability of lineage extinction. The genetic structure was highly significant with the highest variance partition found among regions. Geographic distance and mitochondrial differentiation were not congruent. Lineages had overlapping ranges. The clear genetic differentiation and the patchy pattern of haplotype distribution suggest that colonization of formerly unsuitable habitats was mainly achieved from multiple populations from within the permafrost area.

Keywords: AMOVA - Arianta arbustorum - dispersal - mitochondrial DNA - phylogeography - Pleistocene - polymorphism - refugia

We examined visiting patterns of pollinators of Betonica officinalis L. (Lamiaceae) in experimentally fragmented calcareous grasslands and corresponding control plots at two study sites (Movelier and Nenzlingen) in the north-western Swiss Jura mountains. Fragments (1.5x1.5 m) were isolated by a 5-m wide strip of frequently mown vegetation while the control plots were situated in the adjacent undisturbed vegetation. The most common pollinator, the bumblebee Bombus veteranus (Apidae), visited fragments 53.7% less frequently than control plots. Furthermore, a change in foraging behaviour of Bombus veteranus was observed. In fragments the bumblebees visited more inflorescences, flew longer total visiting distances and the visiting time per patch tended to be higher than in control plots. The distribution of angles between arrival and departure direction (turning angles) differed from a uniform distribution in fragments but not in control plots. The increased directionality of bumblebee flight might be due to a decrease in floral rewards. Our results show that small-scale habitat fragmentation can affect plant pollination at two levels both relevant for plant fitness. First, lower visitation rates indicate a limitation of pollinators which might result in reduced seed set of the pollinated plant. Second, changes in pollinator behaviour might reduce pollen dispersal among flowers, increase inbreeding and hence reduce genetic variability in populations of this bumblebee pollinated plant.

Keywords: Betonica officinalis - Bombus veteranus - bumblebee - gene flow - plant-pollination interaction

The effects of disturbance by recreational activities (trampling) on changes in soil organic matter (SOM) and on mycorrhizal roots of seedlings and mature trees were studied in four stands of a beech (Fagus sylvatica L.) forest near Basel, Switzerland. At each site, comparable disturbed and undisturbed plots were selected. Disturbance reduced ground cover vegetation and leaf litter. Beech seedlings had lower biomass after disturbance. Ergosterol concentration in seedling roots, an indicator of mycorrhizal fungi, was lower in two of the four disturbed plots compared to undisturbed plots; these two disturbed sites had especially low litter levels. Based on ergosterol measurements, mycorrhizas of mature trees did not appear to be negatively affected by trampling. Total fine roots and SOM were higher in the disturbed than in the undisturbed plots at three sites. At the fourth site, fine roots and SOM in the disturbed areas were lower than in the undisturbed areas most probably due to nutrient input following picnic activities. Principal component analysis revealed a close correlation between SOM and fine roots of mature trees as well as litter and seedling biomass. Trampling due to recreational activities caused considerable damage to the vegetation layer and in particular to the beech seedlings and their mycorrhizal fine roots, whereas, roots of mature trees were apparently resilient to trampling.

Keywords: ectomycorrhiza - ergosterol - Fagus sylvatica - fine roots - forest ecosystems - recreational activities - soil compaction - trampling - understorey

Habitat destruction and degradation are the major causes for the decline of the endangered grass-feeding flightless beetle Dorcadion fuliginator in Central Europe. We examined habitat characteristics at 19 localities which still support abundant D. fuliginator populations in the southern part of the Upper Rhine valley (border region of Switzerland, Germany and France) to obtain basic information for the management of deteriorating habitats with declining beetle populations. Populations of D. fuliginator were found in different types of grassland on south, south-west and south-east facing slopes and flat ground. Correspondence analysis showed that plant communities of D. fuliginator localities overlap widely with fertilized, dry hay meadows (phyto-sociologically defined as dry type of the Arrhenatheretum community) and to a minor extent with traditionally extensively cultivated dry grasslands (Xerobrometum and Teucrio-Mesobrometum communities). Average indicator scores of the plant communities characterize the habitat of D. fuliginator as fairly light-exposed and warm, but with relatively large ranges in humidity and nutrient content. The results of a 16-year study on the timing of emergence of the first beetles in a population provided further evidence for the high temperature requirements of D. fuliginator. Proposed conservation measures include traditional cultivation of the present secondary, man-made D. fuliginator habitats, introduction of beetles to suitable motorway embankments as well as large-scale measures allowing natural dynamics in the flood plain along the river Rhine, the presumably primordial habitat of this highly endangered beetle.

Keywords: beetle - grassland type - habitat degradation - habitat requirement - management plan - species conservation

The number of sperm delivered is an important determinant for achieving fertilization in sperm competition. Hermaphroditic gastropods with short mating intervals may deplete their autosperm reserves, An earlier study showed that individuals of the simultaneously hermaphroditic land snail Arianta arbustorum need at least 8 days to replenish their autosperm reserves after a successful copulation. and that the number of sperm transferred in the second copulation slightly increased up to an intermating interval of 4 weeks. We compared spermatophore size. number of sperm delivered, and mating behavior in snails with longer intermating intervals. Snails that remated after 7-8 weeks did not differ in spermatophore size and number of sperm transferred from individuals that remated after 3-4 weeks. The number of sperm delivered averaged 2,151,000 in the first copulation and 2.130.000 in the second Copulation. Snails with a longer intermating interval showed a shorter courtship. but did not differ in copulation duration from snails which remated after 3-4 weeks. Furthermore, different intermating intervals did not affect female fecundity (number of eggs produced and hatching success of eggs). These results indicate that A. arbustorum entirely replenishes its autosperm reserves within 3-4 weeks after a successful copulation.

Keywords: Gastropoda - populations - spermatozoa - size - stylommatophora - Opisthobranchia - allocation - storage

1. The fungal endophyte Epichloe bromicola causes choke disease on Bromus erectus, thereby suppressing maturation of host inflorescences. We conducted a 3-year field experiment to investigate the effects of small-scale habitat fragmentation on the occurrence of choke disease in three calcareous grasslands in the Swiss Jura Mountains, where, overall, 4.3% of all flowering tillers had diseased inflorescences.
2. The number of diseased B. erectus plants (presumed genets), the number of tillers with diseased inflorescences, and the number of tillers with healthy inflorescences were counted over 3 years, but healthy tillers could not be allocated to particular genets. Each of 12 blocks contained one large (4.5 x 4.5 m), one medium (1.5 x 1.5 m) and two small (0.5 x 0.5 m) fragments and corresponding control plots. The percentage of tillers in the plots that were infected but did not show disease symptoms (asymptomatic plants) was estimated in the final year of the study using a diagnostic polymerase chain reaction. On average 1.7% of all tillers without disease symptoms were infected.
3. There were significantly more diseased plants in fragment than in control plots, particularly in small fragment plots or in the third year of the study, indicating that disease incidence in the host plant increased after fragmentation if assessed at the level of the genet population. This was probably due both to a switch of genets from the asymptomatic to the symptomatic state and to increased horizontal transmission of the disease in fragments.
4. The increase in the number of flowering tillers with diseased inflorescences was outweighed by that in the number of tillers with healthy inflorescences. Disease incidence was therefore decreased by fragmentation if assessed at the level of the host flowering tiller population. The effect on healthy plants was probably due to beneficial abiotic edge effects following fragmentation.
5. Plot size affected fragmentation response, with the largest increases in small, followed by medium and large fragments. Similarly, the strength of fragmentation responses increased through time over the 3-year study period.
6. Significant site to site and year to year variation in the number of diseased plants and in the number of tillers with diseased inflorescences suggested that separate experiments with replication within site and year would have yielded a series of interesting but individually different results. Only by repeating the experiments at several sites and over several years was it possible to obtain the general results reported in the previous points.

Keywords: calcareous grassland - clonal plants - diagnostic polymerase chain reaction (PCR) - endophytes - environmental change - habitat fragment size -plant-pathogen interactions

This study explored consumption of a generalist herbivore feeding on leaf tissue of various plant species of a calcareous grassland, and tested whether consumption levels and preferences changed when plants were exposed to 5 years of in situ CO₂ enrichment. The first part of this experiment tested whether the consumption patterns of slugs (Deraceras reticulatum) observed in single-species feeding tests were altered when slugs were given a choice of food sources. Overall consumption increased 270% when slugs were given a choice, and they preferred having a choice of food sources more than they preferred having any one food source. Surprisingly, slugs consumed fewer legumes and grasses and more non-leguminous forbs when given a choice. In the second part of this experiment, feeding behaviors of slugs in response to elevated CO₂ were investigated by feeding them leaves of two legumes, one grass, and a non-leguminous forb (Trifolium medium, Lotus corniculatus, Bromas erectus, and Sanguisorba minor, respectively) in two or four species combinations. In the leguminous species mix, the non-leguminous species mix, and the combined mix (legumes and non-legumes), neither overall consumption by herbivores nor species preference was significantly altered by long-term CO₂ enrichment. In the combined species mix, slugs preferred legumes to non-legumes (P=0.012) and exhibited a weak functional group preference shift from non-legumes to legumes (P=0.089) in response to CO₂ enrichment. This is the first time such a shift has been observed, and provides evidence that there may be multiple herbivore responses to rising atmospheric CO₂ concentrations. Numerous single-species feeding tests using insects have shown that consumption by herbivores may increase when herbivores are fed plants grown in enriched CO₂ atmospheres. This study clearly demonstrates the limited applicability of non-choice feeding trials to generalist herbivores in species-rich communities.

Keywords: deciduous forest - human trampling - picnic site - restoration - soil compaction - species composition

In several families of terrestrial pulmonates, simultaneously hermaphroditic animals form a sharp, hard, calcified or chitinous structure (the so-called love dart) in the female part of their reproductive organs. The dart is used to pierce the body of the mating partner during courtship. The adaptive significance of this peculiar behaviour is still little understood. We examined dart shooting, autosperm delivery, and allosperm storage in three natural populations of the simultaneously hermaphroditic land snail Arianta arbustorum in the Austrian Alps. Twenty-six (30.2%) of 86 copulating snails used their dart. The frequency of dart shooting tended to vary among populations. There was no reciprocity in dart shooting: individuals shot their dart independently of the behaviour of the mating partner. The number of spermatozoa delivered ranged from 522 000 to 4 238 000 (mean 1 706 000). The occurrence of dart shooting was related to neither the number of sperm delivered nor the number received from the partner. The occurrence of dart shooting was not influenced by the amount of allosperm from previous matings stored in the spermatheca of the dart shooters in two populations. In the third population, however, dart shooters had stored more allosperm in their spermatheca than non-shooters. The number of sperm received was not correlated with the size of the donor or the size of the recipient, indicating that snails do not allocate more sperm to larger partners. Experimental results showed that snails which mated under laboratory conditions did not differ in dart-shooting frequency from snails which mated in the wild.

Keywords: Helix aspersa - love-dart - spermathecal morphology - Gastropoda - courtship - Pulmonata - spermatozoa - Helicidae - Mollusca - calcium

It is generally assumed that butterflies, as is the case with many holometabolous insects, rely primarily on nutrients gathered by larval feeding for somatic maintenance and fecundity. These reserves can be supplemented by adult feeding and in some cases by nuptial gifts passed from the males to the females during mating. Recent findings indicate that female butterflies detect and prefer nectar with high levels of amino acids, thus calling new attention to this nutritive source. Polyandrous species can further supplement their larval stores with additional nuptial gifts. This study examined how mating frequency of the polyandrous butterfly Pieris napi affects the female's preference for nectar amino acids. Females of this species generally detect and prefer nectar mimics containing amino acids. However, nectar amino acid preference is significantly lower in mated females. Furthermore, nectar amino acid preference increases when females are not allowed to remate, whereas the preference of twice-mated females remains constant at a lower level. These results indicate a versatile response of females to nectar amino acids, depending on their nutritional status; they may even switch their source of amino acids between adult feeding and nuptial gifts.

Sperm competition theory predicts that males exposed to an increased risk of sperm competition should maximize fertilization prospects by inseminating more sperm per ejaculate. We designed a laboratory experiment to examine the effect of increased sperm competition risk on male and female reproductive traits in individuals of the simultaneously hermaphroditic land snail Arianta arbustorum. Courtship behaviour, spermatophore size and number of sperm delivered were not influenced by a higher sperm competition risk. However, snails constantly exposed to mucous trails of conspecifics deposited more egg batches than snails denied any cues from conspecific mucous trails. On the individual level, the number of sperm delivered was positively correlated with the number of eggs produced. This finding contradicts the basic prediction of sex allocation theory that there is a trade-off between resources allocated to male and female function in simultaneous hermaphrodites. Most probably this trade-off may only occur if resources are limited.

Keywords: Arianta arbustorum - land snail - reproduction - simultaneous hermaphrodite - sperm competition risk

We examined the effect of intermating interval on spermatophore size and number of sperm delivered in the simultaneously hermaphroditic land snail, Arianta arbustorum. Snails that remated after 6-7 d transferred smaller spermatophores which contained fewer sperm than snails that remated after eight and more days. This indicates that individuals of A. arbustorum need at least 8d to completely replenish their sperm reserves after a successful copulation. We suggest that the interval between two copulations is also influenced by the energy costs of the longlasting courtship behaviour with extensive mucus production.

Keywords: competition games - gastropoda - allocation - depletion - pulmonata - cricket - choice

Molluscs are numerically the second largest phylum in the animal kingdom with more than 120'000 living species, which are divided into eight classes. The visual differences between a snail, a clam, and a squid, each an example of a major class of the molluscs, belie the closeness of their relationship. Sexual behaviour is also extremely variable in this phylum. Many species are promiscuous and there are different forms of sperm storage, providing the potential for sperm competition. However, with few exceptions, evolutionary and behavioural aspects of sperm competition have not been examined in this phylum. Most of the available evidence for sperm competition is molluscs is published in studies with other aims and therefore is indirect.
This chapter presents different lines of evidence which suggest that sperm competition might be important in the evolution of the reproductive behaviour in some groups of molluscs. It also shows that there are huge gaps in our understanding of the reproductive behaviour of molluscs. [...] The following provides a taxonomic account of reproductive morphology, physiology and behaviour that potentially have implications for sperm competition.

Three different methods (mark-release-recapture, cardboard trapping and soil sampling) were used to examine the community structure of terrestrial gastropods in an unfertilised, calcareous grassland in the Swiss Jura mountains. The three methods differ in the extent of disturbance to gastropods and damage to the vegetation, in weather dependence and in the spatial scale they can be applied. Although the species patterns obtained by these methods were similar, the three methods yielded different abundances in different species. This can partly be explained by the fact that gastropod species associated with dry grasslands are highly variable in their behaviour (activity rhythm, microhabitat preference and degree to which they climb on vegetation). However, Vertigo pygmaea was the most abundant snail species in all three methods used (82% of all individuals with mark-release-recapture, 58% with cardboard trapping and 58% with soil sampling). We conclude that cardboard trapping might be best suited to examine population biological questions in selected species over relatively large areas of grassland. In contrast, stratified soil sampling might be the most reliable method to obtain complete species lists (species richness) in small areas of grassland.

Keywords: population estimate - mark-release-recapture - cardboard trapping - soil sampling - gastropod community - species assemblage

The feeding behaviour of juveniles of the land snail Helix pomatia was examined in model plant communities consisting of Trifolium repens, Hieracium pilosella, Bromus erectus and Prunella vulgaris that are common species in extensively managed calcareous grasslands in the Swiss Jura mountains. The plant communities were grown either at ambient (350 ppm) or elevated (600 ppm) CO₂ concentrations. Leaves of T. repens and P. vulgaris grown in elevated atmospheric CO₂ had a lower specific leaf area, and leaves of T. repens had lower percentage N on a dry weight basis than leaves grown under ambient CO₂ concentration. Snails fed on all four plant species, but showed a overwhelming preference for T. repens (percentages of total biomass consumed were 91.9 % at 350 ppm and 97.6 % at 600 ppm). The species-specific feeding intensity of juvenile H. pomatia did not differ between the two treatments. The total dry weight of T. repens consumed by the snails was marginally greater (P = 0.06) at elevated CO₂, but there were no significant differences in leaf N or leaf area eaten. These findings are similar to numerous other studies showing that invertebrates increase their consumption of plant material to balance reductions in plant N concentrations at elevated CO₂ treatments. Helix pomatia that fed on plants grown at elevated CO₂ atmosphere showed a larger increase in relative wet weight than those that fed on plants from ambient CO₂ conditions. However, the weight gain of H. pomatia was poorly correlated with amount of plant tissue consumed, so we suggest that the effect of CO₂ on weight gain in H. pomatia was due to a change in the quality of T. repens leaves.

Keywords: Helix pomatia - Trifolium repens - elevated carbon dioxide - herbivory - food choice

We examined the diversity of vascular plants, butterflies, grasshoppers, gastropods and carabid beetles in three calcareous grasslands in the northwestern Swiss Jura mountains, a habitat type that has decreased dramatically during the recent decades. As many as 58 species (ca 22%) of the 266 collected are listed as threatened in northern Switzerland. The number of threatened species ranged from 27 to 49 per site, and 26 species occurred in only one of the three grasslands. The species richness of butterflies and vascular plants correlated positively among the grasslands, while the species richness of other groups did not covary. An index of complementarity indicated that the species compositions (including non-threatened species, and spiders and oribatid mites) of the groups varied greatly among the grasslands. In addition, herbivorous groups were more widely distributed than predators among the three grasslands. Due to this variation in species composition none of the three sites can substitute for the others, if the biodiversity of these grasslands is to be maintained. Furthermore, the taxonomic groups studied are poor indicators of each others' diversity. Consequently, we support the 'shopping basket' approach to conservation evaluation, i.e. measuring species richness, species composition and complementarity of several groups instead of just one.

Keywords: species diversity - threatened species - indicator species - calcareous grassland - Switzerland

Plant-herbivore interactions may change as atmospheric CO₂ concentrations continue to rise. We examined the effects of elevated atmospheric CO₂ and CO₂-exposure chambers on the grazing damage to plants, and on the abundances of potential herbivores (terrestrial gastropods and grasshoppers) in a calcareous grassland in the Jura mountains of Switzerland (village of Nenzlingen). Individuals of most plant species examined showed slight grazing damage. However, plots with CO₂ enrichment and plots with ambient atmosphere did not differ in the extent of grazing damage. Similarly, plots with CO₂ enrichment and plots with ambient atmosphere did not differ in either gastropod or grasshopper density. Experimental plots with and without chambers did not differ in the number of gastropods. However, the densities of gastropods and grasshoppers and extent of grazing damage to plants were generally lower in the experimental area than in the grassland outside the experimental field.

Keywords: herbivore - terrestrial gastropod - grasshopper - density - calcareous grassland - CO₂ enrichment - SACC-experiment

A previous study showed negative effects of inbreeding on reproductive success in the simultaneously hermaphroditic land snail Arianta arbustorum. Different mechanisms of inbreeding avoidance such as kin recognition, sex-biased dispersal patterns, and variation in mating systems have evolved in a variety of organisms. We performed mate-choice tests to examine whether individuals of A. arbustorum discriminate between full-sibs and non-sibs from the same population, and whether incestuous matings reduce the snails' subsequent reproductive success. Snails mated randomly with respect to degree of relatedness, indicating a lack of inbreeding avoidance by selective mating. Snails which mated with full-sibs did not differ in number of eggs, hatching success of eggs, and number of offspring produced from those mated with unrelated conspecifics. Our results indicate that there is no kin recognition mechanism in A. arbustorum. We suggest that multiple mating with different partners, as observed in the field, may reduce inbreeding effects in this species.

Keywords: inbreeding - mate choice - gastropod - pulmonate - hermaphrodite

HPLC-analysis was used to determine the concentrations of the lichen compounds alectoronic acid (depsidon), alpha-collatolic acid (depsidon) and atranorin (depsid) in the lichenized ascomycete Tephromela atra (syn. Lecanora atra) (Hudson) Hafellner from limestone walls on the Baltic island of bland, Sweden. In 24 individuals of T. atra sampled on a stone wall, the pre-reproductive and reproductive tissue did not differ in the concentrations of alectoronic acid, collatolic acid and atranorin. The concentrations of the three lichen compounds were inter-correlated in the reproductive tissue, but not in the pre-reproductive tissue. Single individuals of T. atra ranged in area covered from 10.1 to 147.4 cm² (mean: 38.5 cm²; N=24); 38.6% of this area was pre-reproductive tissue. However, the concentrations of the three lichen compounds were correlated neither with the total area covered by the lichen nor with the percentage of pre-reproductive tissue. This suggests that the concentrations of the lichen compounds do not change with increasing size (age) of the lichen. Analysis of specimens of T. atra from eight localities revealed a significant variation in lichen compounds (range between localities: alectoronic acid 0.60-3.26 mu g/mg lichen dry weight (DW); collatolic acid 2.14-11.59 mu g/mg lichen DW; atranorin 0.58-4.16 mu g/mg lichen DW). The level of grazing observed in the lichens differed significantly among localities. However, no correlations between the concentrations of the three lichen compounds and the grazing damage to the lichens were found.

Keywords: lichens - lichen compounds - herbivory - defense - chemical variation

Habitat type may influence dispersal in a variety of animal species We examined dispersal in the rock-dwelling land snail Chondrina clienta m a limestone pavement, on vertical rock walls, a pile of stones and a stone wall on the Baltic island of Oland, Sweden. Dispersal was estimated by recording movements of marked C. clienta in natural populations over 3 yr Dispersal differed significantly between habitat types. The largest distances dispersed were recorded in the limestone pavement (264 cm yr, median distance) and on vertical rock walls (96 cm yr), simple habitats for travelling snails. Dispersal was less in the stone pile (68 cm yr) and on the stone wall (88 cm yr) that are more complex habitats with multiple layers of pieces of stones. Distances dispersed also varied among vertical rock walls, indicating that other factors such as exposure of the rock surface and size of the habitat may be important in determining snail dispersal. The results of two experiments indicated that grassland vegetation may inhibit dispersal in C.clienta, and that isolated stones covered with lichens might serve as stepping stones for dispersing snails in otherwise unsuitable grassland. Snail size (age) influenced distances moved, but might only be important in determining daily movements, not dispersal over longer periods. Dispersal in C. clienta is habitat-specific and cannot be characterized by a single parameter

Diversity of the calcicolous lichen flora and grazing damage to lichens were recorded on 12 limestone walls in the grassland Great Alvar on the Baltic island of Oland, southeastern Sweden. Grazing damage of lichens was compared with the abundance of potential lichen herbivores (land snails and oribatid mites). A total of 52 Lichen species, 2 lichen parasites, one alga, 2 bryophytes, one vascular plant (Sedum acre) and cyanobacteria, most of them belonging to the family Chroococcaceae, were found on the upper layer of the stone walls. The number of lichen species encountered on single stone walls ranged from 21 to 33. Between-wall differences in species richness were not due to differences in sampling effort. Similarity coefficients of species composition showed a high similarity of the lichen communities between stone walls. Aspicilia calcarea was the dominant lichen which covered on average 66.1% of the upper surface of the stone walls (range among stone walls: 11.9-89.8%). Grazing damage was recorded in 33 (63.5%) of the 52 lichen species. In general, lichen species that occurred frequently were more severely damaged than rare lichen species, although 5 frequent species showed no grazing damage at all. Six species of land snails and oribatid mites were encountered on the stone walls. Two of the snail species (Chondrina clienta and Balea perversa, both known as lichen feeders) were abundant on some stone walls. The proportion of lichen species that showed,orating damage was not influenced by the presence/absence (and density) of either snail species or mites except that the level of grazing damage in the dominant lichen species A. calcarea was correlated with the local population density of B. perversa.

Keywords: biodiversity - calcicolous lichens - gastropods - herbivory - mites - species diversity

A total of 32 calcicolous lichen species, one alga and one bryophyte were recorded on a limestone wall in the grassland Great Alvar on the Baltic island of Öland, Sweden. Fourteen (41%) of these 34 species and free-living cyanobacteria showed herbivore damage, most probably due to grazing by the land snails Chondrina clienta and Balea perversa which inhabited the limestone wall. Three laboratory experiments were conducted to examine the food preferences of individuals of C. clienta and B. perversa collected at this site and to evaluate any association between their preference and the net food quality of the lichens to the snails. Chondrina clienta and B. perversa exhibited food preferences, which differed significantly between species. Within species, variation in food choice was similar among individuals. This indicates that snail populations may be composed of polyphagous individuals with similar food preferences. Different lichen species were of different net food quality to the snails as indicated by growth rate differences. In both snail species the most preferred lichen species of the choice experiment caused the largest weight increase in juveniles, viz. Caloplaca flavovirescens for C. clienta and Aspicilia calcarea for B. perversa. This suggest that the snail species studied differ in their abilities to deal with secondary compounds and physical characteristics of certain lichens or that they can utilize the energy and nutrients of these lichens to a different extent. It is suggested that differential food preferences might reduce the intensity of interspecific competition for resources (lichens) between C. clienta and B. perversa.

Keywords: Gastropoda - lichen grazing - food preference - secondary compounds - interspecific competition

Intraspecific variation in the proportion of offspring sired by the second mate with a female (P2) is an aspect of sperm competition that has received little attention. I examined the effects of delay between copulations (range 9-380 days) and size of sperm donor on sperm precedence in double-mated individuals of the simultaneously hermaphroditic land snail Arianta arbustorum. Using shell colour as a genetic marker, paternity was analysed in 132 broods produced by 35 snails that had mated with two partners of different genotype. Sperm precedence (P2) was influenced by the time between the two matings when the mating delay exceeded 70 days (one reproductive season). P2 averaged 0.34 in the first brood of snails that mated twice within 70 days indicating first mate sperm precedence. In contrast, P2 averaged 0.76 in broods of snails that remated in the following season, indicating a decreased viability of sperm from the first mate. The size of sperm-donating individuals had no effect on the fertilization success of their sperm in the first brood produced after the second copulation. Analysis of long-term sperm utilization in 23 snails that laid three to nine egg batches over 2 years revealed striking differences among individuals. Five snails (21.7%) exhibited first-mate sperm precedence throughout, eight snails (34.8%) showed second-mate sperm precedence throughout, whereas ten snails (43.5%) exhibited sperm mixing in successive batches. It is suggested that the individual variation in sperm precedence in A. arbustorum may partly be due to differences in the amount of sperm transferred. Paternity analysis in 34 batches laid by 19 wild-caught individuals of A. arbustorum indicated that at least 12 snails (63.2%) used sperm from two or more mates for the fertilization of their eggs. This suggests a high incidence of multiple paternity is broods of A. arbustorum under field conditions.

Keywords: sperm precedence - multiple paternity - remating interval - mate size - gastropods

1. A field survey revealed that the land snail Arianta arbustorum had become extinct at 16 (55.2%) out of 29 localities in the surroundings of Basel (Switzerland) between 1908 and 1991. Habitat destruction by urban development was the reason for extinction of eight local snail populations. However, A. arbustorum also became extinct at eight localities, which were covered by vegetation suitable for the species and which still supported abundant populations of other helicid snail species including Cepaea nemoralis (all of them recorded in 1906-8).
2. Localities where A. arbustorum persisted and localities where it went extinct did not differ in exposure, inclination, percentage of woody plant cover, height of ground vegetation, distance to the nearest water body and number of other helicid snail species present. However, localities retaining A. arbustorum were situated on average at higher altitude than localities where it went extinct.
3. Remote sensing was used for mapping the surface temperature in the surroundings of Basel. During summer (when snail eggs were deposited) the surface temperature of the vegetation was significantly higher at localities where A. arbustorum went extinct compared to localities where the species still occurred. The surface temperature of the vegetation extracted from the satellite imagery was significantly correlated with the mean maximum temperature recorded in situ in potential oviposition sites of A. arbustorum at weekly intervals during summer 1992. The satellite imagery showed that built-up areas (central business district and industrial areas) affect adjacent vegetation areas by emitting thermal radiation. This suggests that local climatic warming due to extensive urban development might have caused the extinction of A. arbustorum populations.
4. One possible mechanism might be that egg development of A. arbustorum is sensitive to high temperature; embryos die if the ambient temperature exceeds a specific threshold. To test this hypothesis, we incubated eggs of A. arbustorum and C. nemoralis in the laboratory at 19, 22, 25 and 29 °C. Hatching success for eggs of A. arbustorum decreased from 81.5% at 19 °C to 38.7% at 22 °C, and no eggs hatched at higher temperatures. In contrast, eggs of C. nemoralis had a significantly higher hatching success than eggs of A. arbustorum at 22 and 25 °C. A second experiment demonstrated that exposure to 25 or 29 °C for only 24 h was enough to lower significantly the hatching success of A. arbustorum eggs.
5. These results suggest that temperature tolerance in egg development can determine the distribution of a snail species and, in case of climatic warming, cause its extinction.

Keywords: extinction - gastropods - climate change - temperature tolerance - thermal radiation

We examine whether pioneer species of terrestrial gastropods (snails and slugs) possess particular life history traits commonly associated with r-selection, using data on gastropod colonization in four areas in north-west Europe (the Kvarken and Tvärminne archipelagos in the Baltic, polder woods in IJsselmeer, and a rehabilitated quarry near Maastricht). Data on age at first reproduction, longevity, clutch size, egg size and lifetime fecundity were gathered from the literature. In order to control for potentially confounding effects of body size on life history traits, we compared the residuals from the allometric relations between life history traits and body size for pioneers and non-pioneers. In snails, all life history traits examined were related to body size. In slugs, all traits except age at first reproduction scaled with body size. Body sizes did not differ between pioneers and non-pioneers in any area. In all four areas, there were no significant differences between pioneers and non-pioneers in any of the life history traits examined, after body size had been taken into account. This indicates that pioneer terrestrial gastropods generally cannot be regarded as r-selected. Pioneer species may possess any of several life history strategies, and the combinations of traits shown by them may have little in common with the r-K selection concept.

Keywords: Mollusca - pioneers - life history - colonizing ability - r-selection

Several species of simultaneously hermaphroditic land snails show a genital dimorphism: aphallic individuals differ from euphallic ones by a lack of male copulatory organs (penis and genital retractor muscle). Aphallic individuals can self-fertilize or outcross as females but not as males. Thus, the mating system of a population may be significantly influenced by the proportion of aphallic individuals. We present data on the frequency of aphally in 21 natural populations of the rock-dwelling land snail Chondrina avenacea in the surroundings of Basel, Switzerland. The populations varied greatly in percentage of aphallic individuals, ranging from 0.9 to 89.2% (grand mean 41.2%). This variation did not follow any discernible geographical pattern. The proportion of aphallic snails within a population was influenced neither by local population density nor by any other habitat characteristics - (exposure of rock face, altitude of locality, number of other snail species present). The populations varied significantly in adult shell size. Within populations, aphallic individuals tended to be smaller than euphallic ones. After controlling for size differences, the reproductive organs amounted to 28.3% of the total body mass in aphallic snails and to 31.7% in euphallic snails in a population. This difference can be explained by the absence/presence of male copulatory organs, whose dry weight was 3.2% of the total body mass of euphallic individuals. Monthly sampling of snails from one population revealed that individuals of Chondrina avenacea did not change their sex type over the course of one year.

Keywords: dimorphism - sex allocation - habitat - frequency - seasonal variation - hermaphroditism - self fertilization - Switzerland - Europe - Gastropoda - Mollusca - Invertebrata

The relationships between the number of oocytes, size of oocytes, and body size were examined in a population of the kleptoparasitic bee Nomada lathburiana (Kirby 1802) in Central Sweden. Most females have 5 ovarioles in each ovary with an average of 17.3 mature and nearly mature oocytes in both ovaries. The number and size of mature and nearly mature oocytes increase with bee body size. Females collected at different times of day do not differ in oocyte number. The size-related fecundity in N. lathburiana might be of adaptive significance not only by the enhanced capacity to lay more eggs, but also by the production of larger larvae which may enjoy an increased survivorship.

Keywords: fecundity - oocyte size body size relationship - oocyte number - ovariol number - kleptoparasitic bee - Nomada lathburiana - Anthophoridae

An experiment was conducted to examine whether extended courtship display (a major component of mating behaviour) or repeated copulation in the course of a reproductive season stimulates egg production in the simultaneously hermaphroditic land snail Arianta arbustorum. Repeated copulation was found to increase the number of eggs produced while courtship display did not appear to affect egg production. However, repeated copulation neither accelerated the onset of egg laying nor increased the hatching success of eggs. These results suggest that reciprocal intromission and/or receipt of a spermatophore, but not the long-lasting courtship behaviour, stimulates egg production in A. arbustorum.

Keywords: Arianta arbustorum - courtship - egg production - Gastropoda - repeated copulation - simultaneous hermaphrodite - Stylommatophora

Reproductive isolation was examined in the simultaneously hermaphroditic, self-incompatible land snail Arianta arbustorum. We tested individuals from two geographically isolated populations in Sweden and three populations in Switzerland. In mate-choice tests, within-population (homotypic) and between-population (heterotypic) meetings occurred among snails in frequencies expected by chance. We found no significant difference in courtship latency and courtship duration between homotypic and heterotypic pairs. However, snails from three populations preferred to mate with homotypic partners. Mating preferences could partly be explained by differences in mating propensity in two out of three populations, but not in matings between a Swedish and a Swiss population. Cross breeding demonstrated a high degree of reproductive compatibility between these two distant populations. In contrast, heterotypic pairs involving two Swiss populations had a reduced fertility. The experimental results indicate that partial premating and postmating isolation may exist between distant populations of A. arbustorum. However, the degree of isolation is not related to the geographical distance between populations.

Keywords: courtship - fecundity - gastropod - isolation - mate choice - reproductive compatibility

Keywords: feeding preference - Cyanobacteria - Lichenes - growth - feeding - bacteria - Thallophyta - Gastropoda - Mollusca - Invertebrata

Diastereomers of the spiroacetal, 2,8-dimethyl-1,7-dioxaspiro [5.5]undecane, represent main components of the cephalic secretion from males of the solitary bee, Andrena wilkella. The major compound proved to be of high enantiomeric purity, showing (2S,6R,8S) configuration. Only the naturally occurring enantiomer attracted patrolling males in the field; its antipode was behaviorally inactive and in a racemic mixture did not inhibit response. The (E,Z) diastereomers were also found to be almost inactive. EAG studies gave the same result as the behavioral tests. The biological function of the spiroacetal is discussed in view of the evolution of the mating behavior in A. wilkella.

Keywords: enantiomer discrimination - male patrolling - odor marking - Hymenoptera - Apoidea - Andrena wilkella - bee - EAG - spiroacetal - absolute configuration - 2,8-dimethyl-1,7-dioxaspiro[5.5]undecane

Hatchlings of the land snail Arianta arbustorum (L.) were used to test whether the ingestion of conspecific eggs confers nutritional advantages to a cannibal in terms of increased growth rate and survival. In the field, hatchlings of A. arbustorum consume unhatched sibling eggs as well as eggs from neighbouring batches. In a laboratory experiment, 20 newly hatched sibling snails from each of 24 egg batches were divided into two groups and fed either conspecific eggs or lettuce for 10 days. Growth during this period was recorded, as well as subsequent growth and survival to maturity. During this latter period the animals of both groups were kept under identical conditions and fed on lettuce. Hatchlings fed a cannibalistic diet during their first 10 days of life experienced an increase in wet weight 2.6 times as high as those fed on lettuce. Diet did not affect hatchling survival, but it did influence future survival: 66.6% of the individuals initially fed on eggs attained adulthood compared to 38.0% of those fed on lettuce. Cannibalistic hatchlings tended to complete shell growth more rapidly and thus became mature earlier than non-cannibalistic ones, but the two groups did not differ in adult shell size. Thus, a cannibalistic diet during the hatchling stage will give accelerated growth and higher survival.

Genetic differentiation of the rock-dwelling land snail Chondrina clienta was examined by enzyme electrophoresis in five isolated populations of an outlying area (the Baltic island of Öland, Sweden), and in one population from the species' main range (eastern Alps, Austria). Patterns of allelic variation were compared for 17 putative gene loci involving ten protein systems. All individuals from the five isolated populations on Öland were identically homozygous at all gene loci assayed. Snails from the eastern Alps were homozygous and allelically identical, but they differed by one isozyme band that was absent in animals from Öland and by different alleles fixed at three loci. The absence of isozyme variation and anatomical evidence indicate that self-fertilization may be the prevailing type of reproduction in C. clienta. The allelic identity of the five populations on Öland suggests that they were derived from a single strain, the origin of which probably consisted of one or few self-fertilizing individuals which colonized the island.

Keywords: reproductive isolation - polymorphism - Gastropoda - enzyme - isozyme - geographical variation - genetic variability - island - gel electrophoresis - homozygozity - self fertilization - mating system - population genetics - Mollusca - Invertebrata

Laboratory tests were conducted to examine whether egg-laying Arianta arbustorum prevents egg cannibalism in its offspring by the choice of oviposition sites. Arianta arbustorum did not react to the presence of conspecific eggs when starting to oviposit, thus exposing its eggs to the risk of between-batch cannibalism. Snails preferred to oviposit in soil of higher moisture content even at high air humidity, reducing the risks of later egg desiccation and within-batch cannibalism. Both the types of oviposition sites chosen and their spatial distribution, as observed in 11 natural populations of A. arbustorum near Uppsala, Sweden, suggest that abiotic factors, such as a permanently moist microhabitat, may exert a stronger selection pressure on the oviposition-site choice than does between-batch egg cannibalism.

Keywords: cannibalism - desiccation - oviposition - site selection - Arianta arbustorum

(1) The life history of the polymorphic land snail Arianta arbustorum was investigated in live natural populations along an altitudinal gradient from 1220 to 2600 m in the Swiss Alps. In order to assess the environmentally-induced variation of reproductive characters snails were transplanted to the lowlands.
(2) Adult size decreased from 19.9 to I6.0 mm (mean shell breadth) with increasing altitude, age at maturity increased from 1.9 to 5.0 years, but median adult longevity and adult survival rates were approximately the same at all altitudes.
(3) Clutch number, clutch size, egg size and reproductive investment per year decreased with increasing altitude in resident snails, whereas reproductive investment per egg increased. Within populations, clutch number, number of eggs produced per year and egg size scaled allometrically with shell size indicating a size-specific fecundity.
(4) Transplanted snails laid 1.3-11.5 times more clutches than did resident snails. However, no differences in clutch size, egg dry weight and hatching success were found between transplanted and resident snails, except in one population, in which transplanted snails laid smaller clutches with larger eggs and scored a lower hatching success.
(5) Transplanted snails were less variable in reproductive characters than resident ones, except for hatching success.
(6) In general, life-history characters did not appear to be correlated with shell or body colour.
(7) Although proximate factors like temperature explain most of the variation in life history, evidence was obtained also for genetic divergence among populations. The results match the predictions of the adversity selection model well, rather than those of bet-hedging or r/K-selection.

The relationships between local population density and adult size, clutch size and spatial distribution of egg batches were investigated in 11 natural populations of the land snail Arianta arbustorum in a forest near Uppsala, Sweden. Shell size of adults decreased with increasing population density as did clutch size. Within populations, clutch size scaled allometrically with shell size indicating size-specific fecundity. It is hypothesized that food unpalatability caused by mucus deposition slows down juvenile growth rate in high density populations, resulting in small adults and thus reducing their fecundity in subsequent years. The influence of the distance between batches on the incidence of egg cannibalism by hatchlings was examined in a laboratory experiment. In this experiment the number of eggs cannibalized increased with decreasing distance to the batch of hatching snails. Thus, in the field, eggs of highly aggregated batches suffer a high risk of cannibalism. In the 3 populations with the highest snail density, 21-39% of all batches were deposited close to each other (nearest neighbour distance ≤5 cm, i.e. less than hatchlings more within 1 day). These findings indicate that egg cannibalism can act as a population regulating factor.

Keywords: population regulation - shell size - fecundity - cannibalism - gastropoda

We have examined correlates of land snail colonizing ability in two land uplift archipelagos in the Baltic, using literature data on the orders of colonization and on life histories, mating systems, habitat niche breadths, abundances and habitat requirements. No correlations between life history traits associated with the r-K-continuum and the orders of colonization could be found. Our results suggest that the availability of suitable habitats on islands partly, but not exclusively, determine the orders of colonization. Species with broader habitat niches were more abundant in the source areas, and tended to colonize islands earlier than habitat specialists. Information about mating systems suggests that self-fertilization is more common in colonizers than in non-colonizers. The importance of phenotypic plasticity and dispersal ability for colonizing ability is discussed, and it is concluded that colonization success cannot be predicted from life history traits commonly associated with r-selection.

The resting behaviour of the land snail Arianta arbustorum (L.) from different geographic areas in the eastern Swiss Alps was compared under uniform conditions in order to examine whether local populations had evolved adaptive differences. Differences were observed in resting site preferences of snails from different geographic provenances, which did not seem to be associated with any environmental variables. The observed patterns support the electrophoretic evidence from other studies that there is gene flow between geographically very close populations, above all, along streams. This gene flow may swamp incipient behavioural changes. Morphological differences in shell features, however, appear to take place in spite of gene flow.

Factors affecting oophagy among siblings in the land snail Arianta arbustorum were studied in 3 populations from different altitudes in Switzerland. The degree of egg cannibalism in A. arbustorum is a function of hatching asynchrony since the earliest hatched snails will devour the unhatched eggs in the same clutch. Clutch size, egg density and amount of vegetable food available to newly hatched snails did not affect the degree of cannibalism. Snails from 3 populations were similar in terms of incubation time and intrinsic hatching asynchrony of the clutches. However, they differed in degree of cannibalism when the hatching asynchrony had been experimentally increased. Snails from a lowland forest showed a higher degree of cannibalism than did those from an alpine mountain slope. The parent snails differed in terms of incubation time and hatching synchrony in their clutches. Under natural conditions, the length of the hatching spread and, as a result, the degree of cannibalism will depend additionally on the mode of oviposition (batches or single; clumped or dispersed), on the spatial heterogeneity of egg-laying places and on climatic conditions (e.g. drought).

Keywords: Arianta - Pulmonata - egg cannibalism - oophagy - climate

During field studies on the land snail Arianta arbustorum (L.) in the eastern Swiss Alps the authors repeatedly observed mating snails of which one snail was subadult while its partner was fully grown with a thickened lip. In four instances a record was kept. In one case the subadult snail had a bigger shell size than its adult partner, in the other cases the subadults were smaller. The mating snails from Weissbad and the subadult snail from Savognin were brought to the laboratory and kept isolated in transparent polythene boxes in natural daylight and at a temperature of 19-22 degree C. The subadult snail from Savognin laid 3 clutches of 12, 20 and 14 eggs, the subadult snail from Weissbad 2 clutches of 26 and 39 eggs. Compared with its adult mating partner, the subadult snail from Weissbad produced fewer and smaller eggs. On the other hand, the hatching rate of the subadult's eggs was higher. The present observations show that A. arbustorum is capable of reproducing while still subadult. Formerly, helicids were considered to be mature only when fully grown and with a thickened lip at the aperture of the shell.