Dynamic of the B Chromosome’s System in the Population of the Korean Field Mouse Apodemus Peninsulae (Mammalia, Rodentia) from the Northern Region of the Teletskaya Taiga of Altai Mountains Over a 36-Year Period

The process of changes of the number and morphology of B-chromosomes in the populations of mice (Apodemus peninsulae) in the northern region of the Teletskaya taiga of Altai Mountains: over a 36-year period (1978‒2014) was traced. Three time’s phases can be distinguished. From 1978 to 2002 (24 years) – a phase of steady growth in the number of B chromosomes, with a relatively uniform average increase of 1.4 chromosomes per decade (from 3.17 ± 0.2 to 6.5 ± 0.54). The stabilization’s phase of the indicator in a narrow range of 6.3‒6.9 (2002‒2012), but at more than a twofold high level compared to the beginning of the 1980s (differences are significant) and the period (2012‒2014) of the emerging trend towards a decrease in the number of additional chromosomes (differences are also significant). The change in the index of the conditional mass of B chromosomes (mB) also has similar dynamics, and during the period of stabilization it was at its maximum for the species. The dynamics of different types of B-chromosomes shows an unequal contribution to the overall dynamics. The main contribution is made by macro-B-metacentrics. Micro-B-chromosomes and acrocentrics are absent in the growth phase and appear in the stabilization phase at the maximum of other indicators.