Motility in bacterial coexistence
My group is interested in developing new assays to study the temporal dynamics of biological systems, ranging from protein folding to evolution. In this talk, I will focus on a project that we completed recently on the role of bacterial motility in coexistence. Specifically, we found that motility-driven competition produces strong negative frequency-dependent selection, in which each strain outcompetes the other when low in frequency. This inversion of competitive hierarchy is caused by active spatial segregation and exclusion within the colonized nutrient patch. It is lost for weak growth-migration trade-offs and a lack of virgin space, but is surprisingly robust to initial cell ratio, density, and chemotactic ability, and is observed for laboratory strains as well as for wild strains isolated from single hosts. The findings indicate that motility differences and growth trade-offs can promote diversity, and suggest roles for motility in collective expulsion-containment strategies and niche-formation. If time allows, I will also present work on the causes of epistasis and genetic constraint in gene regulatory networks.
All are welcome to attend.