Pleistocene extinctions and recent expansions in an anguid lizard of the genus Pseudopus

Climatic changes during the Pleistocene played an instrumental role in the shaping recent distribution and diversity of the Western Palearctic biota. Range oscillations often lead to allopatric differentiation followed by the establishment of secondary contact zones. As a result, many species are composed of complex networks of phylogenetic lineages with different histories. Pseudopus apodus is the only surviving member of an ancient genus of Western Palearctic anguid lizards (Anguidae) distributed from the Balkans through Anatolia and Caucasus to central Asia. Here, we used mitochondrial and nuclear DNA sequences to reconstruct the evolutionary history of the species in phylogeographic and demographic frameworks. Our analyses revealed three main phylogenetic lineages that diverged during or shortly before the Pleistocene. Two of them more or less correspond to the known subspecies, and their low genetic variability suggests relatively recent dispersal and colonization of vast parts of the range. The third, southern, lineage is more geographically restricted and diversified than the other two. This pattern shows that the Quaternary climatic oscillations presumably caused repeated large-scale population extinctions of the species, depleting most of its diversity. Only a few refugia located in Anatolia, Levant, and Transcaucasia served as sources for subsequent recolonization to the areas of the recent distribution. This is in contrast to many other Western Palearctic reptiles that survived unfavorable climatic conditions in numerous local refugia and sanctuaries, which resulted in more complex phylogenetic structure.