Spatial patterns of genetic relatedness in two populations of the subterranean rodent Ctenomys talarum.

CUTRERA, A.P & E.A. LACEY

Humboldt University. Arcata, California, USA

Congreso; 84th Annual Meeting of the American Society of Mammalogists.; 2004

American Society of Mammalogists

Kinship is expected to play a significant role in shaping the genetic structure of mammalian populations.  As part of ongoing studies of the population genetics of the subterranean rodent Ctenomys talarum (Ctenomyidae), we examined spatial patterns of kinship in two populations of this species that differ significantly with respect to several fundamental demographic attributes.  Specifically, at Mar de Cobo (MC), adult density is higher, sex ratios are more female biased, dispersal is more male biased, and polygyny is more pronounced than at Necochea (N). These demographic differences are associated with different levels of genetic (microsatellite) variation, with N being the most genetically variable. Here, we examine how levels of genetic relatedness in these populations are distributed in space, with emphasis on differences in relatedness among males versus females.  Given apparent interpopulation differences in dispersal, we predict that genetic relatedness will be more spatially structured in MC than in N and that, in both populations, kin structure will be more pronounced in females than in males. To test these predictions, all individuals in two ~ 1-ha areas at MC and in two ~ 1.5-ha areas at N were live-trapped during the year 2002. All animals caught were individually marked using an ankle ring; a non-destructive skin sample was obtained from each individual captured. Genetic relatedness among animals was assessed using microsatellite markers developed for ctenomyids and analysed using KINSHIP 5.0. We found that, in both populations, spatial distance among females but not among males was negatively correlated with genetic relatedness. The spatial distribution of kinship, however, suggests that females from N disperse further than females from MC. The implications of these findings for patterns of genetic structure in each population are discussed.