I am interested in mammalian social behavior, particularly social structure, parental care, and mating systems. My research is focused on understanding the adaptive benefits of living in groups by investigating the subterranean rodent, the colonial tuco-tuco (Ctenomys sociabilis). Endemic to a small region in southwestern Argentina, the tuco-tuco lives in kin-based groups of 1-6 females and often one male. Nearly all females breed regardless of group size. With such variation, I can compare fitness in females living alone with those living together. Currently, I am examining how stress differs and impacts reproductive success between lone and group-living females. The physiological links that mediate the interactions between an animal and its environment may provide new insight into the adaptive bases of group living.