Research
My research focuses on the ecology and evolution of viruses.
I use an experimental evolution approach with Pseudomonas bacteriophage φ6 to study the origins and maintenance of diversity. Experimental evolution is an approach that allows us to directly test fundamental questions in ecology and evolution in real time. We can initiate evolution experiments from genetically identical ancestors and then evolve these populations under different conditions. Additionally, we can evolve several replicate populations under the same conditions to test the repeatability of evolutionary outcomes. We can also freeze samples of the populations as they evolve, allowing us to create a frozen fossil record and compare the fitness of ancestors to that of their descendants.
Ecology has profound impacts on a virus’s ability to jump hosts. I study this by testing how competition drives host range expansion in φ6. When viruses have fewer host cells to infect, they are more likely to evolve to jump to a novel host. In φ6, The environment plays a critical role in whether or not these generalists will experience a cost for jumping hosts. When generalist φ6 experiences selection in multiple host environments, it is less likely to experience costs in its ability to use its original host.
Theory predicts that generalists carry costs in their ancestral environment, i.e. antagonistic pleiotropy. In the case of viruses, mutations that allow the infection of novel hosts should be costly on ancestral hosts. Evidence for this cost has been mixed at best. I am interested in what other costs generalists might incur, and I suggest that generalists using multiple environments experience relaxed selection in any one environment, producing greater relative lag load. Additionally, mutations fixed by generalist lineages early in their evolution that avoid or compensate for antagonistic pleiotropy may limit access to certain future evolutionary trajectories.
Studying viruses in the lab has inspired me to wonder how the patterns I observe in the lab translate to viruses in the wild. Recent advances now allow us to study the microbial world that had been largely invisible until recently. I have focused on RNA viral communities associated with agriculturally-relevant plants. I have found that such communities associated with white clover (Trifolium repens) are dominated by a single viral species, white clover mosaic virus (WClMV). Despite the low interspecies diversity, there is very high intraspecies diversity within WClMV.