Molecular Ecology (2005) 14, 2511–2523 doi: 10.1111/j.1365-294X.2005.02551.x © 2005 Blackwell Publishing Ltd Blackwell Publishing, Ltd. Genetic structure in a solitary rodent (Ctenomys talarum): implications for kinship and dispersal A. P. CUTRERA,* E. A. LACEY † and C. BUSCH * *Laboratorio de Ecofisiología, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, CC 1245 Mar del Plata, Argentina, †Museum of Vertebrate Zoology and Department of Integrative Biology, University of California, Berkeley, CA 94720 USA Abstract The genetic structure of a population provides critical insights into patterns of kinship and dispersal. Although genetic evidence of kin structure has been obtained for multiple species of social vertebrates, this aspect of population biology has received considerably less attention among solitary taxa in which spatial and social relationships are unlikely to be influenced by kin selection. Nevertheless, significant kin structure may occur in solitary species, par- ticularly if ecological or life history traits limit individual vagility. To explore relationships between genetic structure, kinship, and dispersal in a solitary vertebrate, we compared pat- terns of genetic variation in two demographically distinct populations of the talar tuco-tuco (Ctenomys talarum), a solitary species of subterranean rodent from Buenos Aires Province, Argentina. Based on previous field studies of C. talarum at Mar de Cobo (MC) and Necochea (NC), we predicted that natal dispersal in these populations is male biased, with dispersal distances for males and females being greater at NC. Analyses of 12 microsatellite loci revealed that in both populations, kin structure was more apparent among females than among males. Between populations, kinship and genetic substructure were more pronounced at MC. Thus, our findings were consistent with predicted patterns of dispersal for these animals. Collectively, these results indicate that populations of this solitary species are characterized by significant kin structure, suggesting that, even in the absence of sociality and kin selection, the spatial distributions and movements of individuals may significantly impact patterns of genetic diversity among conspecifics. Keywords: Ctenomys, dispersal, genetic structure, kinship, microsatellites, tuco-tucos Received 13 October 2004; revision received 1 February 2005; accepted 17 February 2005 Introduction The spatial distribution of genetic variation provides critical insights into numerous aspects of a species’ biology, in- cluding patterns of kinship and social structure (Sugg et al . 1996; Chesser 1998; Dobson et al . 1998). In particular, because the spatial distribution of closely related genotypes (i.e. those that share recent co-ancestry) is strongly influenced by individual movements ( Lacey 2000; Matocq & Lacey 2004), genetic evidence of kin structure may provide essential information regarding patterns of dispersal (Daly & Patton 1990; Sugg et al . 1996). For example, analyses of the spatial scales over which kinship is evident may yield estimates of typical dispersal distances (Matocq & Lacey 2004). At the same time, differences in the spatial structure of kinship among males vs. females may provide evidence of sex-biased dispersal (Gompper et al . 1998; Goudet et al . 2002). Finally, estimates of kinship among potential reproductive partners may generate insights into the role that inbreeding avoidance plays in determining patterns of individual movements (Perrin & Mazalov 1999, 2000). Given the central role that kinship plays in studies of social behaviour (Hamilton 1964; Sherman 1981), relation- ships between dispersal, kinship, and genetic structure have been explored in detail for a number of group-living vertebrates (e.g. howler monkeys: Pope 1992, 1998; lions: Spong & Creel 2004; naked mole-rats: Reeve et al . 1990; Faulkes et al . 1997). In comparison, kin structure in solitary species has received considerably less attention (but see Peacock & Smith 1997; Kraaijeveld-Smit et al . 2002). Although members of solitary species exhibit little spatial Correspondence: Ana Paula Cutrera, Fax: 54 223 4753150; E-mail: acutrera@mdp.edu.ar