Distribution of B chromosomes in age categories of the yellow-necked mouse Apodemus flavicollis (Mammalia, Rodentia)

The presence of B chromosomes (Bs) is frequently found in populations of yellow-necked mouse, Apodemus flavicollis. Differences in frequencies of Bs in age categories were analyzed in 717 animals in order to clarify the mechanisms of their maintenance in populations of A. flavicollis. The absence of statistically significant differences in the frequency of Bs between six age categories indicates that the maintenance of Bs in populations can be explained by in terms of their contribution to overall genetic diversity of the species rather than by parasitic behavior