Chromosomal and Molecular Studies of Cryptic Species of the Subgenus Terricola (Rodentia, Arvicolinae, Microtus) in the Caucasian Region: Analysis of New Records

Using chromosomal and molecular (cytb) markers, the specific identity of 78 individuals of cryptic species of voles of the subgenus Terricola was ascertained. The animal samples were obtained at 13 localities of the Caucasian region, from Krasnodar krai to North Ossetia in the Greater Caucasus and in the Stavropol Upland (forest island in the steppe) in Ciscaucasia, which had not been covered earlier in genetic studies. In the total sample, two chromosomal forms (cryptic species), namely, Microtus (Terricola) majori (2n = 54, NF = 60) and M. (T.) daghestanicus (2n = 54, NF = 58), were identified. The specific identity of most animals tested was confirmed by karyological means, and for individuals from two localities on the south slopes of the Greater Caucasus (Adlerskii district of Krasnodar krai), it was confirmed exclusively by means of molecular (cytb) markers. The last two records were used for evaluation of the differential role of sibling-species of the subgenus Terricola in circulation of the pathogen in mountain loci of hemorrhagic fever with renal syndrome (HFRS) in the Western Caucasus. For the first time, using the example of M. (T.) majori from the Ciscaucasia, which was compared with those of the mountain part of the species' natural habitat, the role of isolation factors in morphogenesis of the subgenus Terricola was studied. As a whole, the results obtained specify the character of the geographical distribution and biotope attachment of cryptic species of the subgenus Terricola in the Caucasian region.