Host-microbiome coevolution promotes cooperation in a rock-paper-scissor dynamic

Abstract

Cooperation is a fundamental behavior observed in all forms of life. The evolution of cooperation has been widely studied, but almost all theories focused on the cooperating individual and its genes. We suggest a different approach, taking into account the microbes carried by the interacting individuals. Accumulating evidence reveal that microbes can affect their host wellbeing and behavior, yet hosts can evolve mechanisms to resist the manipulations of their microbes. We thus propose that coevolution of microbes with their hosts may favor microbes that induce their host to cooperate. Using computational modeling, we show that microbe-induced cooperation can evolve and be maintained in a wide range of conditions, including when facing hosts resistance to the microbial effect. We find that host-microbe coevolution leads the population to a rock-paper-scissors dynamic, that enables maintenance of cooperation in a polymorphic state. This theory may help explain occurrences of cooperation in a wide variety of organisms, including in cases that are difficult to explain by current theories. In addition, this study provides a new perspective on the coevolution of hosts and their microbiome, emphasizing the potential role of microbes in shaping their host behavior.