Genetic homogeneity in a Pontocaspian crested newt species (Triturus karelinii) suggests recent isolation of its three allopatric range sections

The integration of multilocus datasets and species distribution modelling in phylogeography allows for the reconstruction of more detailed historical biogeographical scenarios than based on mtDNA data alone. We here combine these approaches to investigate the range dynamics of the crested newt Triturus karelinii, an amphibian species endemic to the Pontocaspian region, whose range comprises three allopatric range sections: a Crimean, a Caucasian and a Caspian range section. In a previous mtDNA phylogeographical survey it was suggested that the Caucasian range section was colonized from the Caspian one and that the Crimean range section was subsequently colonized from the Caucasian one. Newly collected nuclear DNA data reveal little genetic differentiation between the three range sections and species distribution modelling suggests that they only recently became isolated. Taken together, our analyses agree with a recent colonization of the Crimean range section, but rather suggest long-term persistence in both the Caspian and Caucasian range sections, with extensive gene flow between the two.