Microbial population dynamics and selective advantage in microchannels

Spatial barriers affect evolution of cell populations. In this project, we explore bacteria Escherichia coli proliferating in rectangular microchannels with two open ends. For our analysis, we employ a lattice model, in which cells shift entire lanes toward an open end after each reproduction. We find that, due to the shape of the microchannels, populations form a regular stripe pattern of co-specific cells along the rigid boundaries of the channels. We also demonstrate that a random mutation appearing in the middle of the channel is much more likely to reach fixation. Moreover, we find that natural selection is much weaker in this case compared to well-mixed populations. Our theoretical predictions are in good agreement with experimental observations of proliferating Escherichia coli in a microfluidic device. Our results shed light on the effect of shifting dynamics on populations evolution in channels, and have potential applications ranging from microbial ecology in soil to dynamics of epithelial tissues in higher organisms.