Abstract
The evolution of cooperation is one of the most important problems in biology. The evolutionary game theory is a useful approach for investing this problem, and some researchers have recently improved it by adding another game to the dynamics. This framework is known as “multi-games”. In this paper, we investigate the effect of the stochastic sexual interaction on the evolution of asexual cooperation. Our scenario is based on the life cycle of Dictyostelium discoideum, which has two cooperative phases: asexual fruiting body formation and sexual macrocyst formation. We assume that fruiting body formation is represented by the Prisoner’s Dilemma game, while macrocyst formation provides the constant benefits; we focus on the evolution of cooperation in fruiting body formation. Our model shows that cooperators can eliminate different mating type defectors. This occurs only if the benefit from the stochastic sexual interaction is less than from asexual cooperation. This result suggests that macrocyst formation stabilizes the evolution of cooperation in fruiting body formation to some degree. Next, we investigate the metapopulation dynamics because cooperators are eliminated by the same mating type defectors in our model. The fixation time of defectors slows down due to the stochastic sexual interaction but cooperators finally become extinct. These results suggest that a mating type works as a tag and that D. discoideum avoids the exploitation from defectors by sexual interaction.