title: Cooperation induces other cooperation: Fruiting bodies promote the evolution of macrocysts in Dictyostelium discoideum.
abstract: Biological studies of the evolution of cooperation are challenging because this process is vulnerable to cheating. Many mechanisms, including kin discrimination, spatial structure, or by-products of self-interested behaviors, can explain this evolution. Here we propose that the evolution of cooperation can be induced by other cooperation. To test this idea, we used a model organism Dictyostelium discoideum because it exhibits two cooperative dormant phases, the fruiting body and the macrocyst. In both phases, the same chemoattractant, cyclic AMP (cAMP), is used to collect cells. This common feature led us to hypothesize that the evolution of macrocyst formation would be induced by coexistence with fruiting bodies. Before forming a mathematical model, we confirmed that macrocysts coexisted with fruiting bodies, at least under laboratory conditions. Next, we analyzed our evolutionary game theory-based model to investigate whether coexistence with fruiting bodies would stabilize macrocyst formation. The model suggests that macrocyst formation represents an evolutionarily stable strategy and a global invader strategy under this coexistence, but is unstable if the model ignores the fruiting body formation. This result indicates that the evolution of macrocyst formation and maintenance is attributable to coexistence with fruiting bodies. Therefore, macrocyst evolution can be considered as an example of evolution of cooperation induced by other cooperation.
authors.affiliation: Department of General Systems Studies, Graduate School of Arts and Sciences, The University of Tokyo, Tokyo 1538902, Japan. Electronic address: shibasaki.sh@gmail.com.
authors.forename: Shota
authors.initials: S
authors.lastname: Shibasaki
authors.affiliation: Department of General Systems Studies, Graduate School of Arts and Sciences, The University of Tokyo, Tokyo 1538902, Japan.
authors.forename: Yuka
authors.initials: Y
authors.lastname: Shirokawa
authors.affiliation: Department of General Systems Studies, Graduate School of Arts and Sciences, The University of Tokyo, Tokyo 1538902, Japan.
authors.forename: Masakazu
authors.initials: M
authors.lastname: Shimada
mesh_terms: D005075:Biological Evolution; D002450:Cell Communication; D003299:Cooperative Behavior; D000242:Cyclic AMP / Q000378:metabolism / Q000502:physiology; D004023:Dictyostelium; D048690:Fruiting Bodies, Fungal / Q000378:metabolism / Q000502:physiology; D044662:Macrocystis / Q000166:cytology / Q000378:metabolism / Q000502:physiology
chemical_list: D000242:Cyclic AMP
keywords: Evolutionarily stable strategy; Evolutionary game theory; Global invader strategy; Social amoeba