The cooperative amoeba: Dictyostelium as a model for social evolution.

Social interactions, including cooperation and altruism, are characteristic of numerous species, but many aspects of the evolution, ecology and genetics of social behavior remain unclear. The microbial soil amoeba Dictyostelium discoideum is a model system for the study of social evolution and provides insights into the nature of social cooperation and its genetic basis. This species exhibits altruism during both asexual and sexual cycles of its life history, and recent studies have uncovered several possible genetic mechanisms associated with kin discrimination and cheating behavior during asexual fruiting-body formation. By contrast, the molecular and evolutionary mechanisms that underlie sexual macrocyst formation remain largely enigmatic. D. discoideum, given its utility in molecular genetic studies, should continue to help us address these and other relevant questions in sociobiology, and thereby contribute to a coherent theoretical framework for the nature of social cooperation.