Speaker
Description
Tremendous progress has been made in quantifying fitness landscapes and elucidating how the effects of available mutations affect the dynamics of single microbial species in simple environments lacking strong ecological interactions. However, it remains largely unclear how natural selection depends and feeds back onto the spatial and community structure characteristic of most natural microbiomes. I discuss two of our attempts to begin filling this gap. First, I describe microfluidic experiments revealing that eco-evolutionary dynamics can be extremely sensitive to the spatial niche available to a population. The second project is focussed on the community structure of the population, aiming at quantifying the evolutionary potential of a nascent bacterial community. By temporally tracking barcoded transposon libraries derived from a long-term evolution experiment in E. coli, we explore how ecological and epistatic effects combine to drive adaptive evolution in a nascent community of closely related, coexisting ecotypes. We find a pronounced frequency-dependence in the distributions of fitness effects, which could promote long-term co-existence in the face of rampant adaptive evolution.
