Phylogeography of the smooth snakeCoronella austriaca(Serpentes: Colubridae): evidence for a reduced gene pool and a genetic discontinuity in Central Europe

Abstract

The present study considers the genetic structure and phylogeography of the smooth snake (Coronella austriaca) in Central Europe, as analyzed on the basis of 14 microsatellite markers and a 284-bp fragment of cytochrome b. We found deep divergence between western and south-eastern Poland, suggesting at least two different colonization routes for Central Europe, originating in at least two different refugia. The west/south-east divide was reflected in the haplotype distribution and topology of phylogenetic trees as defined by mitochondrial DNA, and in population structuring seen in the admixture analysis of microsatellite data. The well supported western European clade suggests that another refugium might have existed. We also note the isolation-by-distance and moderate-to-pronounced structuring in the examined geographical demes. Our data fit the assumption of the recently suggested sex-biased dispersal, in that we found a strong divide in the maternal line, as well as evidence for a small but existent gene flow based on biparentally inherited microsatellite markers. All studied populations were very similar in respect of allelic richness, observed and expected heterozygosities, and inbreeding coefficients. However, some genetic characteristics were different from those expected compared to a similar fine-scale study of C. austriaca from Great Britain. In the present study, we observed heterozygosity deficit, high inbreeding, and low Garza–Williamson indices, suggesting a reduction in population size. © 2015 The Linnean Society of London, Biological Journal of the Linnean Society, 2015, 115, 195–210.