The plot thickens: a new social tuco-tuco from northern Argentina

LACEY, EILEEN A.; CUELLO, PABLO A.; WOODRUFF, JULIE A.; TAMMONE, MAURO N.; WIECZOREK, JOHN R.

Congreso; 91st Annual Meeting of the American Society of Mammalogists; 2011

Independently evolved examples of group living provide valuable opportunities to test hypotheses regarding the adaptive bases for social behavior. Although rodents in the genus Ctenomys are geographically widespread and often locally abundant in sub–Amazonian South America, quantitative evidence of group living in these animals has until now been limited to a single species, the colonial tuco–tuco (C. sociabilis). Here, we demonstrate that the highland tuco–tuco (C. opimus) is also social. Live–trapping and radiotelemetry data indicate that multiple adult C. opimus share the same burrow system and nest site. Unlike C. sociabilis, however, group mates display only partial spatial overlap with one another and groups are not characterized by discrete spatial boundaries. Based on these data, the social structure of C. opimus appears to be intermediate between that of C. sociabilis and strictly solitary species of tuco–tucos. Current phylogenetic information for Ctenomys suggests that C. sociabilis and C. opimus represent evolutionarily independent examples of group living, making them ideal for comparative studies of the adaptive bases for burrow sharing. More generally, this new evidence for behavioral variation among tuco–tucos underscores the importance of ctenomyid rodents for comparative studies of the proximate and ultimate bases for differences in social behavior.