The G-banded karyotype of Sorex satunini was compared with the karyotype of Sorex araneus. Extensive homology was revealed. The major chromosomal rearrangements involved in the evolutionary divergence of these species have been identified as centric fusions and centromeric shifts. From the known palaeontological age of Sorex satunini it is obvious that the vast chromosomal polymorphism of the Sorex araneus group originated during the middle Pleistocene.

The possible role of the population variability in the number and morphological types of B chro mosomes in the plasticity of the species is exemplified by various species of animals and plants.

The examples of various members of the animal and plant species shows a possible role of population variability in the number and morphological types of B-chromosomes in plasticity of the species.

Citation: Borisov YM, Abramov SA, Borisova MY, Zhigarev IA (2020) The occurrence of dot-like micro B chromosomes in Korean field mice Apodemus peninsulae from the shore of the Teletskoye Lake (Altai Mountains). Comparative AbstractThe data on the changes in the cytogenetic structure of the geographic population of Korean field mouse Apodemus (Alsomys) peninsulae Thomas, 1907 at the southern shore of the Teletskoye Lake (Altai Republic) are presented. In 1980 no dot-like microchromosomes were found in 34 mice captured on the southern and northern coasts of the Teletskoye Lake. In 2011, a 1.6-fold (from 2.7 to 4.3) increase in the mean number of B chromosomes compared to the rate estimated there earlier in 1980 was discovered. In 11 of the 15 mice (73%) captured in 2011, the karyotypes contained 1-2 dot-like micro B chromosomes and 1-5 macro B chromosomes. The pollution of the territory by the remains of the rocket fuel components may be an appropriate explanation for the cause of the karyological changes observed in A. peninsulae in this region.