Evolutionary dynamics in large microbial communities

Microbial communities drive important biochemical cycles, from the ocean to the soil to the human gut. High rates of cell turnover endow these communities with an enormous potential for rapid evolutionary change – e.g., billions of new mutations are produced within a single gut microbiome every day. Despite the potential importance of these effects, we currently know very little about the evolutionary dynamics that take place in large microbial communities, and how these dynamics might deviate from our single-species intuition. In this talk, I will describe our recent efforts to address this question using data from the human gut microbiome. I will show how population genetic analysis of sequenced fecal samples can help us quantify the typical timescales of within-host evolution, and how this might constrain the ability of a community to adapt to fluctuating environmental conditions.