Conservation genetics of a wide-ranged temperate snake: same species, different locations, and different behaviour

Jean-Pierre Vacher,Sylvain Ursenbacher,Eric Graitson,Julie Cauwenbergh

doi:10.1007/s10592-021-01416-4

Abstract

Even though reptiles are threatened worldwide, few studies address their conservation, especially snakes. The goal of our study was to measure the genetic structure of a widely distributed temperate reptile, the smooth snake Coronella austriaca using microsatellite markers in two different areas at the core (Alsace, north-eastern France) and at the edge (Wallonia, southern Belgium) of its range. We sampled 506 individuals in 38 localities (respectively 10 and 28). Analysis of genetic structure conducted with a clustering method detected three clusters in Alsace, one group gathering all populations but two. In Wallonia, differentiation was observed on both sides of the Meuse River and in the Southern Ardenne region (southernmost sampling sites). Spatial autocorrelation analysis showed that statisticaly more related individuals occur together up to a distance of 2.8 km in Alsace and up to 10 km in Wallonia. Isolation by distance was detected in Wallonia but the distance explained a very limited part of the differentiation (r = 0.033), whereas no isolation-by-distance pattern was detected in Alsace. Even though genetic differentiation between populations separated by large rivers, highways, or crop fields was detected, dispersal between populations seem currently sufficient to avoid any kind of genetic drift in both regions. These results are similar to a previous study conducted in Poland, but strongly contrast with another analysis held in England which detected a sharp genetic structuring among populations that are geographically close. We consequently suggest that discrepancies could be related to the ecology of island populations and smaller densities.

Highlights

In the scope of the current biodiversity crisis, most studies on animal conservation focus on endangered and highly threatened species (Foden et al 2013; Wagner et al 2014; Howard et al 2020; Loiseau et al 2020)
Even though genetic differentiation between populations separated by large rivers, highways, or crop fields was detected, dispersal between populations seem currently sufficient to avoid any kind of genetic drift in both regions
As no or only weak isolation by distance was detected, it is likely that other processes are influencing the genetic differentiation between populations, such as some landscape elements or historical events that we could not detect with this study

Summary

Introduction

In the scope of the current biodiversity crisis, most studies on animal conservation focus on endangered and highly threatened species (Foden et al 2013; Wagner et al 2014; Howard et al 2020; Loiseau et al 2020). According to the IUCN Red List, one of the major threats to terrestrial wildlife is the destruction of habitats (Pimm et al 2014; IUCN 2020), which induces fragmentation and loss of connexion between populations. Small vertebrates such as reptiles are sensitive to such disturbances, and it has been shown that some populations of common species are exposed to fragmentation, and can become severely threatened (Driscoll 2004; Guiller 2009)

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