Genetic differentiation in populations of the yellow‐necked mouse, Apodemus flavicollis, harbouring B chromosomes in different frequencies

Abstract

Two alternative models are used to explain maintenance of polymorphism of B chromosomes (Bs) in populations of a great number of species. The parasitic model suggests deleterious effects of Bs on fitness of carriers, while the heterotic model assumes that, in the absence of drive, equilibrium is produced by beneficial effects of Bs at low numbers. In order to determine the potential contribution of Bs to genetic differentiation and diversity, four populations of Apodemus flavicollis, differing in frequency of Bs (from 0.23 to 0.38) and settled in ecologically different habitats, were analyzed by 471 AFLP markers. Although numerous loci were demonstrated to be population specific, none of them was associated with individuals with Bs. AMOVA showed that the presence of Bs does not affect population differentiation, pointing to greater genetic similarity of Bs to A chromosomes. The greatest genetic diversity (0.241) was found in the population settled in optimal conditions for this species featured by the lowest frequency of animals with Bs (0.23). We found that the majority of loci marked as loci under directional selection, are characteristic of either a population with lower or one with a higher frequency of Bs. Several loci detected as outliers were associated with environmental variables that could directly and/or indirectly influence population dynamics of A. flavicollis. Thus, we suggest that the different frequency of Bs carriers in populations is related to adaptive differentiation to diverse habitats, which is in accordance with the heterotic model of Bs maintenance.

Exploring Supernumeraries - A New Marker for Screening of B-Chromosomes Presence in the Yellow Necked Mouse Apodemus flavicollis

“…Reported B chromosome prevalence ranged from 11% to 63% in 13 out of 14 populations studied in former Yugoslavia [ 21 , 22 ]. A possible reason for their long-term presence in populations could be their contribution to: genetic variability, adaptive effects and population dynamics [ 22 – 25 ].…”

Diversity of nematodes in the yellow-necked field mouseApodemus flavicollisfrom the Peripannonic region of Serbia

“…Furthermore, population genetics and dynamics also have an influence on the structure of the parasite fauna of the yellow-necked field mouse (Ferrari, 2005) and possibly explain the differences and similarities found here. In a recent study of yellow-necked field mouse populations in Serbia it was shown that their genetic structure did not reflect geographical distances and predicted barriers (large rivers); rather, it reflected differences in the habitats (Adnadević et al , 2012). In particular, the authors found no statistically significant differences in genetic diversity between two localities separated by the Danube.…”

B Chromosomes in Populations of Mammals Revisited

“…Possible adaptive effects of Bs were also postulated by Blagojević et al [ 234 ] upon comparison of head morphology in three populations of this species that have Bs at different frequencies. Adnađević et al [ 235 ], by using amplified fragment length polymorphism (AFLP) markers, made a comparison of populations of A. flavicollis settled in ecologically distinct habitats differing in frequency of Bs, and found that the greatest genetic diversity is in the population settled in optimal conditions for this species featured by the lowest frequency of animals with Bs. The majority of loci that are subject of directional selection, feature either population with lower or with a higher frequency of Bs.…”