Ergänzende Informationen zu Publikationen von Silvia Geser
2022 Multiple paternity in the Asp viper — Nanni-Geser S & Ursenbacher S — Journal of Zoology 318: 158–165 doi> 10.1111/jzo.12999
Many male reptiles maximize their reproductive success by mating with multiple females. This behaviour has often been observed in female reptiles as well, although one mating would usually be sufficient to fertilize the available female eggs. Using 13 microsatellite markers, multiple paternity (MP) was confirmed for the first time in the asp viper (Vipera aspis) in 47% of the tested clutches, with only up to two different fathers. Phenotypic characteristics (length, weight) of the mother did not influence the number of sires, and the number of young did not dif- fer between litters with one or two sires. Males that sired offspring were larger than males that did not successfully reproduce. Excluding an exceptionally long- distance movement (2464 m), the distance between fathers and mothers was limited (127 m 162). Although males exhibit notable combat behaviour during the breeding season, there was no sexual size dimorphism in the study population.
Keywords: Vipera aspis - multiple paternity - sexual size dimorphism - microsatellite - European vipers - reproductive success - reproductive tactics
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2021 Only males care about their environment: sex-biased dispersal in the asp viper (Vipera aspis) — Zwahlen V, Nanni-Geser S, Golay J, Kaiser L, Dubey S & Ursenbacher S — Biological Journal of the Linnean Society 132: 104–115 doi> 10.1093/biolinnean/blaa177
Sex-biased dispersal is common among vertebrates and numerous studies have documented a tendency of male-biased dispersal in mammals and female-biased dispersal in birds. However, relatively few studies have demonstrated that male-biased dispersal seems to be prevalent in reptiles. Moreover, most of these studies considered only a single study site, without including possible local variability. We investigated sex-biased dispersal in Vipera aspis in four study sites in Switzerland using microsatellite markers and predicted a higher dispersal in males than females. In two study sites, females were more spatially autocorrelated and showed a stronger isolation by distance compared to males, which suggest male-biased dispersal. In the other two study sites, the lack of sex-biased dispersal could be the result of habitat fragmentation. Surprisingly, the dispersal ability of females was similar in the four sites, regardless of habitat fragmentation. This finding suggests a limited impact of habitat on female dispersal and the opposite on male dispersal. Our study demonstrates the importance of inferring sex-biased dispersal in different habitats because local barriers can impact the outcome of such studies. Hence, general conclusions about patterns of sex-biased dispersal should be drawn with caution when studies are conducted in a single study site.
Keywords: isolation by distance - reptiles - spatial autocorrelation - Viperidae
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2015 Diversifying selection and color-biased dispersal in the asp viper — Dubey S, Zwahlen V, Mebert K, Monney J-C, Golay P, Ott T, Durand T, Thiery G, Kaiser L, Geser SN & Ursenbacher S — BMC Evolutionary Biology 15: 99 doi> 10.1186/s12862-015-0367-4
Background: The presence of intraspecific color polymorphism can have multiple impacts on the ecology of a species. As a consequence, particular color morphs may be strongly selected for in a given habitat type. For example, the asp viper (Vipera aspis) harbors a high level of color polymorphism with a cryptic morph (blotched) being common throughout its range (central and western Europe). In addition, a melanistic morph is common in montane populations, likely for thermoregulatory reasons. Beside these two morphs, rare atypical lightly colored non-blotched individuals are known, but only in important proportions in a restricted treeless area of the French Alps. The aim of the study is to bring insights into the presence and function of this color morph by (i) studying the genetic structure of these populations with nine microsatellite markers, and testing for (ii) a potential local diversifying selection and (iii) differences in dispersal capacity between blotched and non-blotched individuals.
Results: Our genetic analyses support the occurrence of local diversifying selection for the non-blotched phenotype. In addition, we found significant color-biased dispersal, blotched individuals dispersing more than atypical non-blotched individuals.
Conclusion: We can hypothesize that this atypical non-blotched phenotype has a local advantage, possibly a cryptic function against visual predators, and is consequently better adapted to its open habitat. In addition, color-biased dispersal might be partly associated to the observed local diversifying selection, as it can affect the genetic structure of populations, and hence the distribution of color morphs.
Keywords: diversifying selection - dispersal - coloration - reptile - asp viper
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2013 Development of polymorphic microsatellite markers for the asp viper (Vipera aspis) using high-throughput sequencing and their use for other European vipers — Geser S, Kaiser L, Zwahlen V & Ursenbacher S — Amphibia-Reptilia 34: 1009–113 doi> 10.1163/15685381-00002861
The Asp viper (Vipera aspis) is a highly endangered species in the Plateau and in the Jura Mountains of Switzerland. In the past, numerous populations disappeared due to human activities, but, currently, the trend is inverted and several locations are favourable for this species. However, it is not known if the remaining populations are still genetically variable and viable. In this study, 12 new microsatellite markers were developed for Vipera aspis using Next Generation Sequencing (pyrosequencing) techniques. All markers proved to be polymorphic with 2 - 9 alleles. Additionally, cross- amplification tests for two Eurasian viper species (V. berus and V. ammodytes) showed the applicability of some of these markers for the most widespread European vipers.
Keywords: microsatellite development, Vipera aspis, conservation genetics, 454 pyrosequencing, population structure
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