Variability of Supernumerary Chromosome Morphotypes and the Emergence of Micro-B-Chromosomes in the Karyotype of <i>Apodemus peninsulae</i> (Rodentia) in the Russian Far East

Abstract

Variability in the number and morphotypes of macro, as well as mini and micro B-chromosomes of Apodemus peninsulae in the valley Zeya River from Amur region is described. Micro B chromosomes were found in the karyotypes of the Korean field mice from the Far East of Russia for the first time. Two opposite trends in the geographic variability of B chromosome morphotypes have been identified. The first one is due to the presence/absence of mini and/or micro, in addition to macro B-chromosomes, in animals from the right and left river banks in the northeastern part of the Upper Zeya Plain, as well as in the northern part of the Amur-Zeya Plain. The second is a clinal variability is characterized by a gradual increase in three combined geographic populations of A. peninsulae of numerical parameters of B-chromosomes: index x̄В Max micro, x̄В Max macro, the number of morphotypes, the number of clones in mosaics, and the proportion of mosaics in the direction from north to south of the Zeya River valley. The revealed diversity of A. peninsulae B-chromosome morphotypes for 13 regions allows us to re-evaluate the geographical variability of additional chromosomes of this species in the Russian Far East Adaptive value of B-chromosome morphotypes for the species has been also assumed.