March 27 2017

4:00 pm 158 HH

This seminar is sponsored by EEB and QCB

Nicole Vega
Department of Physics, Massachusetts Institute of Technology

Stochastic and deterministic bacterial community assembly in a C. elegans host model


Despite decades of theoretical and observational investigation, the factors directing community assembly in real ecosystems are still poorly understood. The problem is particularly acute in host-associated systems such as the intestinal microbiota. Furthermore, while these communities are known to vary between hosts, the causes and consequences of this heterogeneity are not well understood.We useC. elegansas a simple model for community assembly in a host environment. Gut-associated communities are assembledde novofrom a set of bacterial species selected to cover a broad taxonomic range and a spectrum of host interactions, including both probiotics and pathogens of the worm\; these results provide insight into the selective forces governing community assembly in this environment. Further, the stochastic forces affecting community assembly are described through modeling and experiments\; the rate of intestinal colonization by bacteria is used to move between drift-dominated and deterministic regimes, and the resulting heterogeneity between individual communities is described. We find that, while the host environment imposes distinct selective pressures on its bacterial contents, stochastic forces are sufficient to produce considerable heterogeneity between individuals.