Genetic Structure Within and Among Populations of the Common Marmoset, Callithrix jacchus: Implications for Cooperative Breeding

Abstract

Cooperative breeding and a reproductive division of labor are characteristic features of callitrichid primates. Of key importance in understanding this kind of social strategy is knowledge of the kin structure of groups, yet until recently the patterns of relatedness within and among social groups have remained unclear, even in the best-studied species such as the common marmoset Callithrix jacchus. Of particular interest is the role of kin selection in helping behavior and group dynamics, and the application of molecular genetic techniques to investigate group structure, dynamics, and parentage is now unequivocally addressing such issues. Both microsatellite genotyping and mitochondrial DNA sequence analysis have revealed that while social groups may often be composed of extended family groups, considerable genetic heterogeneity may also arise as a result of inter-group migrations. In one study, a group of nine animals was shown to contain individuals from five matrilines. The occurrence of groups of mixed lineages raises interesting questions about potential reproductive conflicts of interest and the extent of kin-selected altruism in the evolution and maintenance of cooperative behavior in this species.