Studying Social Evolution in Microcosm

What are the causes, mechanisms, and effects of social evolution? Rice evolutionary biologists David Queller and Joan Strassmann believe that the single-celled social amoeba Dictyostelium discoideum might provide some of the answers. To find out, they are teaming with geneticists and developmental biologists from Baylor College of Medicine on a five-year project funded by a new National Science Foundation program dedicated to taking on grand challenges in biological research.

The project brings together experts in genomics and social evolution to provide the most thorough understanding yet of the genetic basis and evolutionary history of complex social behavior. It is one of just six inaugural projects unveiled in the launch of the NSF’s Frontiers in Integrated Biological Research program. Approximately half of the $5-million award will go to each institution. Baylor co-principal investigators include Adam Kuspa, professor of developmental biology; Gad Shaulsky, assistant professor of molecular and human genetics; and Chad Shaw, instructor of molecular and human genetics.

“ Some of the most significant transitions in evolution—the emergence of chromosomes, cells, eukaryotes, and multicellular organisms—occurred when formerly separate entities overcame conflicts and merged into a greater whole,” says Queller, principal investigator on the project. “So it’s clear that understanding social evolution is central to understanding the very structure of life, yet very little has been done to apply the modern tools of genetics and genomics to the study of social evolution.”

Dictyostelium discoideum is a favorite model system among developmental and cell biologists for studying social evolution because social amoebae work collectively to form colonies. Though the cells in these colonies cooperate, prior studies by Queller and Strassmann have shown how groups of amoebae that contain dissimilar genes compete within the colony to gain a reproductive advantage.

“ The genetic tools and simplicity of sociality in social amoebae make it easier to study the processes of cooperation and conflict that also operate in other organisms,” says Strassmann.

The social evolution project has four goals. First, it will uncover the genes and molecular pathways underlying sociality. Second, it will probe the evolutionary history of these genes. For example, the research will test whether social forces create significant evolutionary pressures, and it will demonstrate the social function of ancestral genes by recreating them and testing them in vivo. Third, the project will generate experimental evidence for how opportunistic, nonaltruistic behavior is controlled—a process that was essential in the major evolutionary transitions noted above. Finally, the knowledge gained in the lab will be used to understand how social evolution works in the wild.

—Jade Boyd