Hydrodynamic flow and concentration gradients in the gut enhance neutral bacterial diversity

D. Labavic , C. Loverdo , A.F. Bitbol

Bibtex , URL
Proc. Natl. Acad. Sci. U. S. A., 119, 1
Published 04 Jan. 2022
DOI: 10.1073/pnas.2108671119
ISSN: 0027-8424


The gut microbiota features important genetic diversity, and the specific spatial features of the gut may shape evolution within this environment. We investigate the fixation probability of neutral bacterial mutants within a minimal model of the gut that includes hydrodynamic flow and resulting gradients of food and bacterial concentrations. We find that this fixation probability is substantially increased, compared with an equivalent well-mixed system, in the regime where the profiles of food and bacterial concentration are strongly spatially dependent. Fixation probability then becomes independent of total population size. We show that our results can be rationalized by introducing an active population, which consists of those bacteria that are actively consuming food and dividing. The active population size yields an effective population size for neutral mutant fixation probability in the gut.