Molecular phylogeny of the genus Alticola (Cricetiidae, Rodentia) as inferred from the sequence of the cytochrome b gene

Central Asian mountain voles Alticola is one of the least known groups of voles both in evolution and life history. This genus includes three subgenera Alticola s.str., Aschizomys and Platycranius, and belongs to the tribe Clethrionomyini comprising also red-backed voles Clethrionomys and oriental voles Eothenomys. In order to elucidate the phylogenetic relationships within Alticola and to examine its position within the tribe, mitochondrial cytochrome b (cyt b) gene variation was estimated, and the results were compared with morphological and palaeontological data. Maximurn likelihood (ML), neighbor-joining (NJ), maximum parsimony (MP) and Bayesian phylogenetic analyses show that the genus Alticola does not appear to be a monophyletic group since the representatives of Aschizomys branch within Clethrionomys, whereas two other subgenera (Alticola and Platycranius) form a separate monophyletic clade. Flat-headed vole Alticola (Platycranius) strelzowi is nested within the nominative subgenus showing close association with A. (Alticola) semicanus. Surprisingly, the two species of Aschizomys do not form a monophyletic group. The results of the relaxed-clock analysis suggest that the Alticola clade splits from the Clethrionomys stem in early Middle Pliocene while basal cladogenetic events within Alticola s.str. dates back to the late Middle to early Late Pliocene. A scenario of evolution in Clethrionomyini is put forward implying rapid parallel morphological changes in different lineages leading to the formation of Alticola-like biomorphs adapted to mountain and arid petrophilous habitats.