Contrasted patterns of mitochondrial and nuclear structure among nursery colonies of the bat Myotis myotis

Thirteen nursery colonies of Myotis myotis were sampled in central Europe to investigate the dispersal behaviour of this bat species. Mitochondrial DNA sequences of 260 bats reveal the occurrence of three evolutionary lineages that have probably originated in distinct glacial refugia and meet in a contact zone near the Alps. Moreover, the strong haplotypic segregation (Phi (ST) = 0.540) suggests that breeding females are philopatric. Contrastingly, the low population structure at 15 microsatellite loci (F-ST = 0.022), suggests the homogenizing effect of nuclear gene flow. The different perspectives given by these two markers are consistent with strong male-biased dispersal. As a result of female philopatry, the local haplotypic variability seems to be largely influenced by historical processes of colonization. Conversely, the homogeneity of nuclear variability within roosts that are located north of the Alps seems to mainly reflect contemporary gene flow. Finally, despite the fact that females are faithful to their natal colony, movements of both males and females occur outside the breeding period. Mitochondrial survey of individuals sampled exclusively in nurseries may thus poorly reflect the metapopulation dynamics of this species.