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Comportamiento social y reproductivo del roedor subterráneo solitarioCtenomys talarum (Rodentia: Ctenomyidae) en condiciones de semicautiverio RESUMENSe estudió el comportamiento social y reproductivo en grupos de individuos del roedor subterráneo Ctenomys talarum (Thomas, 1898) en condiciones seminaturales, que reflejaron la complejidad de las cuevas de la especie así como también la relación de sexos típica de poblaciones naturales. Los datos sugieren que las interacciones entre los individuos son mucho más variadas y complejas que lo esperado para una especie solitaria y territorial. Diferentes canales de comunicación -auditivo, táctil y olfativo-fueron importantes para el establecimiento y mantenimiento de territorios y durante el cortejo y la cópula. Se observaron diferencias en el comportamiento social entre individuos de poblaciones naturales con diferentes características ecológicas. Individuos pertenecientes a la población de Mar de Cobo, que presenta una alta densidad y una proporción de sexos desviada a favor de las hembras, establecieron jerarquías de dominancia entre los machos, lo que determinó el acceso preferencial por parte del macho dominante a varias hembras. La observación de daño físico (heridas) fue común entre machos de la población de Mar de Cobo. En contraste, la agresión entre machos de la población de Necochea, que presenta una baja densidad y una proporción de sexos balanceada, usualmente no resultó en daño físico y no se detectó una jerarquía de dominancia; los machos cortejaron a las hembras aún en presencia de otros machos.Palabras clave: comportamiento social, reproducción, roedores subterráneos, cautiverio, Ctenomys talarum. ABSTRACTThe social and reproductive behavior of the subterranean rodent Ctenomys talarum (Thomas, 1898) was studied in a seminatural enclosure resembling both the complexity of the natural burrow system and the sex ratio observed in wild populations. Contrary to expectations based on their solitariness and their rather simple social system, the interactions among individuals of this species were diverse and complex. Auditory, tactile and chemical communication were of importance during territory guarding, courtship and copulatory behavior. Individuals from different populations differing in ecological attributes behaved in substantially different ways. Males from Mar de Cobo, a population characterized by a high density and a skewed sex ratio favouring females, behaved aggressively, which resulted in frequent wounding. Males from Mar de Cobo established a dominance hierarchy among them, which preceded courtship and, eventually, resulted in the dominant male monopolizing mating activity. On the contrary, males from Necochea, a population showing low density and an even sex ratio, behaved less aggressively; dominance relationships were absent, and males performed courtship behaviors in the presence of other males.

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, particularly if ecological or life history traits limit individual vagility. To explore relationships between genetic structure, kinship, and dispersal in a solitary vertebrate, we compared patterns 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.