New insight into the cradle of the grey voles (subgenus Microtus) inferred from mitochondrial cytochrome b sequences

Abstract

Our aim in this study was to further the under-standing of the taxonomic relationships and the evo-<br><br>lutionary history of grey voles (subgenus Microtus, or arvalis species group) by establishing a cytochrome b (cytb) phylogeny with special emphasis on three species occupying Southwest Asia: Microtus mystacinus (levis is a synonym), Microtus obscurus and Microtus transcaspicus. Phylo genetic trees yielded a sister position of Microtus arvalis + M. obscurus against M. mystacinus while, M. tran-scaspicus emerged as their closest relative. Microtus ilaeus hold a basal position in the subgenus. The only sample <br><br>from Afghanistan was classified into M. transcaspicus, therefore expanding the known geographic range for the species and questioning the presence of Microtus ilaeus in the country. Deep sub-structuring was typical of all the well-sampled species: M. mystacinus, M. obscurus and M. arvalis. Kimura 2-parameter (K2P) genetic diver-gence of 4.1% between the two main clades of M. mys-tacinus [the European (EU) and our new Iranian (IR)] was nearly identical to a distance (4.2%) between M. arvalis and M. obscurus, therefore suggesting undetected cryptic species in M. mystacinus. Our results reflect the importance of the Caspian-Altai zone for a speciation of the grey voles and of the Ponto-Caspian region for the intraspecific diversity of M. obscurus and M. mystacinus. M. arvalis is the only grey vole which diversified outside Asia.