Protectors and killers: the evolutionary ecology of host-microbe interactions.

The body is home to trillions of microbes. There has been a surge of interest on the effects of these microbes on host health, either as agents of infectious disease or in their potential to protect their host from parasite infection. I offer projects broadly focused on the evolutionary and ecological interactions between hosts and their microbes exhibiting traits across the parasitism-mutualism continuum. The projects will involve experimental (co)evolution of bacteria with Caenorhabditis elegans, a model host study system and could take any of the following specific routes:

1) Protective microbes. Microbe-mediated protection is a widespread phenomenon, observed across animals (insects to humans) and plants. Microbes have high evolutionary potential due to their short generation times and large within-host population sizes, and thus might be able to evolve to protect hosts more rapidly than hosts can evolve to defend themselves. Projects here could explore: (i) the roles of variation in parasite attack or transmission modes on the evolution of protective microbes, (ii) the degree to which protective microbes shape the evolution of host responses to infection, and (iii) the effects of host sex, age, and heterogeneity on the efficacy of microbe-mediated protection against infection.

2) Host-parasite coevolution. Studies into coevolution between hosts and parasites have transformed our understanding of the power of species interactions to maintain genetic diversity and drive rapid evolutionary change. Projects here could explore: (i) the effect of host genetic diversity on parasite evolutionary rates and virulence, (ii) whether density-dependent parasite virulence alters coevolutionary dynamics, and (iii) the role of the abiotic environment (i.e., nutrients) on the evolution of host resistance during coevolution.