MiCo-Colloquium

Cooperation and competition in microbial communities

Prof. Dr. Kevin Foster

Department of Zoology, University of Oxford

Since Darwin, evolutionary biologists have been fascinated by cooperative behavior. For example, honeybee workers labor their whole life without reproducing, birds make alarm calls, and humans often help one another. But how cooperative are microbes towards each other and other organisms? We study this question using a diversity of systems, including computer simulations, pseudomonad bacteria and budding yeast. We find that single-genotype patches naturally emerge in microbial groups, which creates favorable conditions for cooperation within a particular genotype of microbe. Moreover, some microbes actively adjust both genotypic assortment and investment into social traits in a way that promotes cooperation within a genotype. However, our work on interactions between different microbial genotypes suggests that, here, the evolution of competitive phenotypes is more likely than cooperation. This leads us to a simple model - the genotypic view - that predicts microbes will evolve to help their own genotype but harm most other strains and species that they meet. When microbes live within a host, however, there is natural selection on the host to ensure that symbiotic communities are both productive and stable. This raises the possibility that hosts act as ecosystem engineers that change the rules of interaction within microbial communities.