Phylogeographic structure of the pygmy shrew: revisiting the roles of southern and northern refugia in Europe.

Abstract

Southern and northern glacial refugia are considered paradigms that explain the complex phylogeographic patterns and processes of European biota. Although the Eurasian pygmy shrew Sorex minutus Linnaeus, 1766 (Eulipotyphla, Soricidae) has been used a model species to study geographic isolation and genetic diversification in Mediterranean peninsulas in the Last Glacial Maximum (LGM), and post-glacial population expansion from cryptic northern glacial refugia in Western and Central Europe, there has been incomplete knowledge about the phylogeographic structure, genetic differentiation and demographic history within these regions. Here, we provide a revisited statistical phylogeographic study of S. minutus with greater sampling coverage in terms of numbers of individuals and geographic range, making it the most comprehensive investigation of this species to date. The results showed support for genetically distinct and diverse phylogeographic groups consistent with southern and northern glacial refugia, as expected from previous studies, but also identified geographical barriers concordant with glaciated mountain ranges during the LGM, early diversification events dated between the Upper Pleistocene and Lower Holocene for the main phylogeographic groups, and recent (post-LGM) patterns of demographic expansions. The results have implications for the conservation of intraspecific diversity and the preservation of the evolutionary potential of S. minutus.