Abstract
Allelic variation at eight microsatellite loci was used to assess the levels of genetic differentiation between seven natural populations of black grouse (Tetrao tetrix) in the French Alps spaced along a 250 km south-north transect. Whatever the population or locus, genotype frequencies did not deviate significantly from expected Hardy-Weinberg frequencies and no significant between-locus linkage desequilibrium was detected. Observed levels of genotypic variation were statistically significant with maximum Fst values reaching 10% for the most distant populations (250 km). An isolation-by-distance effect was detected suggesting, as expected from data on marked birds, that black grouse populations in the French Alps are interconnected by dispersal.