Matrilineal genetic structure and female-mediated gene flow in red grouse (Lagopus lagopus scoticus): An analysis using mitochondrial DNA

DNA sequence variation at the hypervariable 5' end of the mitochondrial con trol region was examined in 247 individuals to detect genetic divergence am ong 14 populations of red grouse (Lagopus lagopus scoticus) in northeastern Scotland. Ten haplotypes were resolved, several of which were shared among populations. Analysis of molecular variance, Nei's gamma(ST), and a cladis tic estimate of the amount of gene flow indicated a lack of overall populat ion differentiation. Patterns of overall panmixia are in stark contrast to previous reports of localized subdivision among the same set of populations detected using hypervariable microsatellite markers. Because grouse cocks are territorial and show extreme natal philopatry and females are the dispe rsing sex, such discordance could be explained by sex-biased dispersal, wit h extensive female-mediated gene flow preventing mitochondrial DNA divergen ce. However, it is difficult to reconcile how effective dispersal of female s would not homogenize both mitochondrial and nuclear structure simultaneou sly. We use a model that examines the spatial and temporal dynamics of dipa rentally and uniparentally inherited genes to show that, under realistic ec ological scenarios and with specitic differences in the dispersal of males and females, the local effective size of the nuclear genome can be less tha n that of the mitochondrial and the patterns of structuring we observe are meaningful.