Eusociality, characterized by cooperative colonies of animals in which most members sacrifice individual reproduction, has long presented a fundamental paradox for behavioral and evolutionary ecology. A comparative approach to deciphering the origins of eusociality, in which the ecology and demographics of eusocial species are contrasted with those of their closest non-eusocial relatives, represents a potentially powerful complement to behavioral studies at the individual and population levels. The potential of this comparative approach remains largely unrealized because eusociality has arisen only rarely among animals, and many of these origins are ancient. This project will reconstruct the phylogenetic relationships among the approximately 40 species of sponge-dwelling alpheid shrimps, and use comparative methods to explore the ecological and demographic conditions associated with the repeated evolution of advanced social organization in this group. Specific objectives of the proposed research are to produce a taxonomic revision of the gambarelloides species-group of alpheid shrimps, establish a strongly supported phylogeny for the group based on DNA sequences and morphology, and use comparative methods to explore the association between ecology and social evolution in sponge-dwelling shrimps. This research will provide a rigorous comparative analysis of the history and ecology of social evolution in the only marine animal group in which advanced social organization is known.
