Predator-prey coevolution in the bacterial world

Marie VASSE

Integrative Biology, ETH, Zurich

Predatory bacteria are pervasive throughout terrestrial and aquatic habitats and, given the importance of predators to macro-organismal communities, are likely to strongly influence microbial community evolution. However, despite their ubiquity and likely importance in shaping prey evolution, research on the ecological and evolutionary impacts of predatory bacteria remains scarce.  Here, we tested how coevolution between a generalist bacterial predator and a bacterial prey species altered the evolution of fitness, genomes and diversity relative to evolution by both parties in isolation. We show evidence of reciprocal adaptation in coevolved communities and greatly accelerated genome evolution relative to controls, including the rapid appearance of mutator genotypes. Further, we found strong parallel evolution among both predators and prey, with predators driving parallel adaptations at two virulence-associated traits among prey. These results with simple two-species communities suggest that generalist predatory bacteria are important determinants of how complex prey communities and their interaction networks evolve and diversify in natural habitats.