Mitochondrial sequences retrieve an ancient lineage of Bicolored shrew in the Hyrcanian refugium

The bicolored shrew Crocidura leucodon consists of two phylogeographic lineages which diverged during the Middle Pleistocene and are roughly separated by the Bosporus Strait at the contact point of Europe and Asia Minor. In this study we analysed mitochondrial cytochrome b genes (1137 bp) of nine shrews from the Caspian region in Iran. Phylogenetic trees obtained in Maximum Likelihood and Bayesian analyses retrieved a sister position of our Iranian haplotypes (Iranian lineage) against all the remaining C. leucodon samples from Europe, Turkey and Georgia (Euro-Asian lineage). Identical topology was also evident from the unrooted phylogenetic network. The Euro-Asian and the Iranian lineages were separated by a K2P genetic distance of 7.5 ± 0.9 and diverged 1.14 Mya (95% CI: 0.841–1.616). The geographic range of the Iranian lineage is evidently restricted to the Hyrcanian region south of the Caspian Sea which abounds with small range mammalian endemics.