The mechanisms of formation and evolution of B chromosomes in Korean field mice Apodemus peninsulae (Mammalia, Rodentia)

Several hypotheses concerning variations in the frequency of some elementary events determining the formation and reorganization of mammalian B chromosomes are proposed on the basis of the data on their number, morphology, and DNA composition in Korean field mice Apodemus peninsulae (Mammalia, Rodentia) from natural populations of Altai, Buryatia, Irkutsk oblast, and Primorye. The mechanisms and causes responsible for the formation of B chromosomes and differences in their organization in populations of mice from geographically separated regions are discussed.