ROSLIK G.V., KARTAVTSEVA I.V., PAVLENKO M.V., BAZHENOV YU.A.
Genetika 2026; 62(4): 97-113
New data on variability of numerical and morphotypic parameters of B chromosomes (Bs) in the Korean field mouse Apodemus peninsulae from forest-steppe and forest biotopes of Zabaikalsky Krai are presented. There were 1-19 B chromosomes in the karyotypes of the studied mice. All individuals contained micro-B chromosomes, predominantly in combination with two-armed small and medium Bs (but not with large ones). Two geographic groups, which significantly differed from each other by the Bs number, indices of the average number Bs per individual (x̄B) and the conditional “mass” of Bs (mB), as well as the number of morphotypes and the frequency of micro-Bs, have been distinguished. In the “northwestern” group of populations, relatively low values of quantitative parameters of Bs are maintained, while in the “southeastern” group, on the contrary, quantitative parameters of Bs are higher. Possible barrier role of large Shilka and Onon rivers, as well as the steppe area in the middle and lower reaches of Onon River in maintaining the numerical and morphotypic differences of B chromosomes between these groups is discussed. It was shown that a decrease in diversity of Bs morphotypes is most characteristic for Korean field mice from forest-steppe biotopes, probably due to the position of these populations at the edge of the species range and their existence in the most pessimal conditions.
