Reciprocal Rewards in the Rhizosphere: Underground markets and the evolution of cooperation in plant-fungal mutualisms.
Toby Kiers
Free University Amsterdam, Department of Animal Ecology, Faculty of Earth and Life Sciences, Netherlands
Associating with microbes in the rhizosphere can have both costs and benefits for host plants. Because associations generally involve multiple microbial genotypes varying in mutualistic benefit, a potential tragedy of the commons can arise. How do plants maintain cooperation with the most beneficial rhizosphere microbes over the course of evolution? Specific mechanisms may be employed that reduce the fitness benefits to microbes from “cheating”. In the mycorrhizal mutualism, the fungal symbiont cannot be “enslaved.” Rather, the mutualism is evolutionarily stable because control is bidirectional, and partners offering the best rate of exchange are rewarded. The existence of underground biological markets will be discussed.
