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Unravelling landscape variables with multiple approaches to overcome scarce species knowledge: a landscape genetic study of the slow worm

Geiser, Céline ; Ray, Nicolas ; Lehmann, Anthony ; Ursenbacher, Sylvain

In: Conservation Genetics, 2013, vol. 14, no. 4, p. 783-794

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    Title
    • Unravelling landscape variables with multiple approaches to overcome scarce species knowledge: a landscape genetic study of the slow worm
    Author
    • Geiser, Céline. Department of Environmental Sciences, Section of Conservation Biology, University of Basel, St. Johanns-Vorstadt 10, 4056, Basel, Switzerland
    • Ray, Nicolas. Laboratory of Spatial Predictions and Analyses in Complex Environments, Institute for Environmental Sciences, University of Geneva, 7, route de Drize, 1227, Carouge, Switzerland
    • Lehmann, Anthony. Laboratory of Spatial Predictions and Analyses in Complex Environments, Institute for Environmental Sciences, University of Geneva, 7, route de Drize, 1227, Carouge, Switzerland
    • Ursenbacher, Sylvain. Department of Environmental Sciences, Section of Conservation Biology, University of Basel, St. Johanns-Vorstadt 10, 4056, Basel, Switzerland
    Document Type
    • Postprint
    OAI-PMH Identifier
    • oai:doc.rero.ch:320822
    Summary
    Landscape genetics was developed to detect landscape elements shaping genetic population structure, including the effects of fragmentation. Multifarious environmental variables can influence gene flow in different ways and expert knowledge is frequently used to construct friction maps. However, the extent of the migration and the movement of single individuals are frequently unknown, especially for non-model species, and friction maps only based on expert knowledge can be misleading. In this study, we used three different methods: isolation by distance (IBD), least-cost modelling and a strip-based approach to disentangle the human implication in the fragmentation process in the slow worm (Anguis fragilis), as well as the specific landscape elements shaping the genetic structure in a highly anthropized 16km2 area in Switzerland. Friction maps were constructed using expert opinion, but also based on the combination of all possible weightings for all landscape elements. The IBD indicated a significant effect of geographic distance on genetic differentiation. Further approaches demonstrated that highways and railways were the most important elements impeding the gene flow in this area. Surprisingly, we also found that agricultural areas and dense forests seemed to be used as dispersal corridors. These results confirmed that the slow worm has relatively unspecific habitat requirements. Finally, we showed that our models based on expert knowledge performed poorly compared to cautious analysis of each variable. This study demonstrated that landscape genetic analyses should take expert knowledge with caution and exhaustive analyses of each landscape element without a priori knowledge and different methods can be recommended