Genomic Signatures of Cooperation and Conflict in the Social Amoeba

• Published in: Current biology Vol. 25; no. 12; pp. 1661 - 1665
• Main Authors: Ostrowski, Elizabeth A., Shen, Yufeng, Tian, Xiangjun, Sucgang, Richard, Jiang, Huaiyang, Qu, Jiaxin, Katoh-Kurasawa, Mariko, Brock, Debra A., Dinh, Christopher, Lara-Garduno, Fremiet, Lee, Sandra L., Kovar, Christie L., Dinh, Huyen H., Korchina, Viktoriya, Jackson, LaRonda, Patil, Shobha, Han, Yi, Chaboub, Lesley, Shaulsky, Gad, Muzny, Donna M., Worley, Kim C., Gibbs, Richard A., Richards, Stephen, Kuspa, Adam, Strassmann, Joan E., Queller, David C.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 15.06.2015
• Subjects: Amoeba; Dictyostelium - genetics; Dictyostelium discoideum; Evolution, Molecular; Genome, Protozoan; Genomics; Polymorphism, Genetic; Selection, Genetic
• ISSN: 0960-9822; 1879-0445
• DOI: 10.1016/j.cub.2015.04.059

Cooperative systems are susceptible to invasion by selfish individuals that profit from receiving the social benefits but fail to contribute. These so-called “cheaters” can have a fitness advantage in the laboratory, but it is unclear whether cheating provides an important selective advantage in nature. We used a population genomic approach to examine the history of genes involved in cheating behaviors in the social amoeba Dictyostelium discoideum, testing whether these genes experience rapid evolutionary change as a result of conflict over spore-stalk fate. Candidate genes and surrounding regions showed elevated polymorphism, unusual patterns of linkage disequilibrium, and lower levels of population differentiation, but they did not show greater between-species divergence. The signatures were most consistent with frequency-dependent selection acting to maintain multiple alleles, suggesting that conflict may lead to stalemate rather than an escalating arms race. Our results reveal the evolutionary dynamics of cooperation and cheating and underscore how sequence-based approaches can be used to elucidate the history of conflicts that are difficult to observe directly. •Molecular evolution analyses reveal the history of social conflict•Genes that mediate social conflict show signatures of frequency-dependent selection•Balanced polymorphisms suggest that cheating may be stable and endemic Cooperative systems are susceptible to cheating, but little is known about whether cheaters are successful in the long term. Ostrowski et al. examine the evolution of genes that mediate social cheating in Dictyostelium discoideum and find patterns of balancing selection, suggesting that cheating may be stable and endemic in natural populations.