Seasonal observations on supernumerary chromosomes mosaicism, and dynamicsin two populations of the Eastern-Asian wood mouse Apodemus peninsulae (Rodentia) from Primorskii krai

Karyotypes of 47 individuals of the wood mice Apodemus peninsulae from two reserves in Primorskii krai (Kedrovaya Pad' and Ussuriiskii) were studied d uring spring, summer, and autumn. In each population, variation in the numb er of B-chromosdmes (2n = 48 + 0-5B) as well as the intratissue mosaicism d etermined by variation of the number, size and morphology of supernumerary chromosomes were described. Animals that have one dotlike B-chromosome were first described in both populations as rare variants. Individuals that hav e bone-marrow cell clones with two or three B-chromosomes were found to be predominant in the populations of Primorskii krai. The number of clones var ied from one to three per animal. The frequency of mosaics showed seasonal variation. In the population of the Ussuriiskii reserve, a sharp increase i n the frequency of animals with a stable karyotype was detected in autumn, at the phase of increased numbers. The variation for mosaicism was suggeste d to correlate with the population numbers in mice and to indicate the gene tic differences between generations of the population.