Genetic differentiation within two large phylogroups of the common hamster (Cricetus cricetus) (Cricetidae, Rodentia), the boundary between them, and the population abundance

clarification. In the course of our specially organized expedition, tissue samples of the common hamster were collected in 12 regions of Russia and Kazakhstan, including areas at the potential border of the ranges of phylogroups “A” and “E” (“Europe”). Analysis of the nucleotide sequences of the cytb gene of the captured animals has shown that the boundary between these phylogroups runs between Turinsk and Yekaterinburg, further between Chelyabinsk and Kurgan, between Omsk and Tatarsk, and turns to the south, leaving the village of Turgai and the town of Temirtau in the west and the village of Bayanaul in the east. The structure of territorial genetic clades belonging to phylogroups “A” and “E” and the history of their formation were also analyzed. Most of the detected territorial clades were formed during the Late Pleistocene and Holocene. The population dynamics of phylogroups “A” and “E” was analyzed and its decline was shown in 8 of the 12 surveyed regions.