Local genetic structure in red grouse (Lagopus lagopus scoticus): evidencefrom microsatellite DNA markers

Allelic variation at seven hypervariable tri- and tetranucleotide microsate llite loci was used to determine levels of population differentiation betwe en 14 populations of red grouse (Lagopus lagopus scoticus) in northeast Sco tland, UK. Despite the potential for long-distance dispersal in grouse, and a semicontinuous habitat, significant population divergence was observed ( mean R-ST = 0.153; P < 0.01) and an isolation-by-distance effect detected ( Mantel test: P< 0.001). Examination of the spatial trend in principal compo nent scores derived from allele frequencies among populations highlighted a barrier to gene flow that was confounding a simple isolation-by-distance e ffect. This barrier corresponded to an area of unsuitable habitat for grous e associated with a river system that bisected the study area. Mean genetic relatedness was higher for males than for females in all but one of the st udy populations, suggesting that the territorial behaviour and natal philop atry displayed by cocks have a manifold effect in generating the observed s patial genetic structure. Lower female relatedness values suggest a higher level of female-mediated gene flow, which is sufficient to prevent the loss of genetic variation from within populations and the onset of inbreeding e ffects. The potential consequences of local subdivision for red grouse popu lations are discussed.