Abstract

Conflicts between individuals of the same species are common in nature and are mostly resolved with limited aggression. Several theoretical studies, such as the Hawk-Dove game model, investigate the evolution of limited aggression expressed during conflicts between individuals. These studies mainly focus on the individuals involved in the conflict and their genes. Recently accumulating evidence indicates that microbes are associated with diverse functions of their host, and can affect host behavior. Here we extend the classic Hawk-Dove game model to include both the hosts and their microbes. We find that non-aggressive host behavior is more likely to evolve and spread in population when induced by the microbes residing in the host, compared to non-aggressive behavior induced by host genes. Our results suggest that microbes may help explain the ubiquity of non-violent conflict resolution. Consequently, factors that alter the microbial composition within hosts may affect the aggressiveness level in host populations.