Contact zones between chromosome races of the common shrew Sorex araneus L. (insectivora, mammalia) at the margins of the Veps stage of the Valdai ice sheet

Cytogenetic analysis of the common shrew populations in the Valdai Hills revealed the presence of four distinct chromosome races (Western Dvina, Seliger, St. Petersburg, and Moscow). The geographic distribution of these races relative to the borders of the Late Valdai glaciation area is described and discussed. Five contact zones between chromosomal races were found, located directly on the ice-marginal formations of the Veps stage. Two races, Seliger and St. Petersburg, are located exclusively in the former ice sheet area. Attention is drawn to the fact that many of the races located in the last glacial area from the Valdai Hills through Scandinavia are characterized by endemic chromosomes (gi, gp, mo, or, etc.). It is concluded that the situation in the former glaciation area could favor the preservation of tundra or forest vegetation refuges and populations of some small mammal species.