Mutualisms are believed to be evolutionarily unstable owing to the opportunity for cheating mutations to arise in either of the interacting species, wherein individuals enjoy the fitness benefits of the mutualism but pay no costs. Unlike the evolution of cooperation from conflict within species where genetic relatedness plays a key role, the absence of relatedness in inter-specific mutualisms is viewed as making the evolution of cooperation from genomic conflict more difficult. We used population genetic models, analytical approximations and computer simulations to investigate the evolution of mutualisms and their evolutionary stability.
Results/Conclusions:
We show that, when relatedness is viewed as a genetic correlation, then there are important parallels between the evolution of mutualisms between species and the evolution of cooperation from conflict within-species. We find that, whenever there is interspecific epistasis for fitness and genetic variation for vertical transmission, the arms race of genomic conflict can evolve into a reciprocal mutualism. Moreover, the evolved mutualism is evolutionarily stable.