The Red King Effect: Evolutionary rates and the division of surpluses in mutualisms

Abstract

Mutualisms generate surpluses. While much of the theoretical literature to date focuses on mechanisms by which cooperation is stabilized so that these surpluses can continue to be produced and enjoyed, we address a second question: how will these surpluses be distributed among the participants? We approach this question from an evolutionary game theory perspective, exploring how the coevolutionary process selects an equilibrium division of the surplus from among the many possibilities.

We place particular emphasis on the importance of the relative rates of evolution of the two species. Contrary to the Red Queen hypothesis, which suggests that fast evolution is favored in coevolutionary interactions, we find that slowly evolving species are likely to gain a disproportionate fraction of the surplus generated through mutualism. This occurs because on an evolutionary timescale, slow evolution effectively ties the hands of a species, allowing it to commit to threats and thus bargain more effectively with its partner over the course of the coevolutionary process.