Estimating the relatedness in a population of grey squirrels Sciurus carolinensis, using DNA fingerprinting

Studies on the behaviour of grey squirrels Sciurus carolinensis Gmelin, 178 8 and other species belonging to the same genus, suggest they exhibit domin ance hierarchies among both males and females, and their mating strategy is promiscuous or polygynous. However, there is little information available on how dominance translates into reproductive success or on the levels of g enetic variation or genetic substructuring within a population. To address these questions, we used multilocus DNA fingerprinting to quantify genetic diversity and estimate relatedness amongst individuals in a free-ranging po pulation of grey squirrels. Background band-sharing values revealed a high degree of genetic diversity existed. The frequency distribution of band-sha ring values between known first order relatives and presumed unrelated anim als was significantly different. Estimates of relatedness between individua ls were therefore based on threshold levels of genetic similarity and used as a tool to infer close kinship. Possible kinship groups were identified u sing the spatial distribution of the home ranges of adults and juveniles. L evels of relatedness between neighbouring adults was low with five family u nits identified comprised of putative parents and their offspring. Several juveniles from the single cohort revealed levels of relatedness intermediat e between first order relatives and unrelated animals, suggesting possible second order relationships leg half siblings) existed. The implications of these relationships are discussed.