Ergänzende Informationen zu Publikationen von Barbara Meister

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

The loss and fragmentation of pristine habitat restrict specialized species to remnants of original habitat patches in a less suitable landscape. This may lead to a genetic differentiation of the subpopulations and to a decline in biodiversity. We used seven microsatellite markers to examine the genetic population structure of the grass snake, Natrix natrix (Linnaeus, 1758), sampled in remnants of pristine habitat in a former wetland in the Swiss lowlands and in a rural valley in the Alps. On a regional level, the population structures of N. natrix in these two areas were compared with that of grass snakes living in an intensively used agricultural area. The three study areas were 30–100 km apart, but were interconnected by the river Aare. At the local scale, no genetic differentiation was found in either of the N. natrix populations inhabiting the rural alpine valley or the intensively used agricultural area. However, two subpopulations in the former wetland area were genetically differentiated with a low but significant FST. This slight genetic differentiation can be explained by isolation by distance. At the regional scale, we found significant genetic differentiation between N. natrix populations inhabiting areas separated by 30–100 km. The genetic structure was highly related to isolation by distance with 85% of the among-populations genetic variance explained by the geographical distance between subpopulations. Euclidian distance explained genetic differentiation of grass snake populations better than the distance following watercourses. Our findings indicate regular gene flow between N. natrix subpopulations and show that this species also moves across intensively used terrestrial habitat. The genetic structure of grass snakes is mainly affected by geographic distance, while human activity and habitat alteration do not seem to reduce the snakes' movements. Our results suggest that conservation actions in human-altered landscapes should focus on the maintenance of a habitat mosaic with anuran breeding ponds and adequate oviposition sites.

Keywords: grass snake - isolation by distance - microsatellite DNA - Natrix natrix - population structure

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