Shearing in flow environment promotes evolution of social behavior in microbial populations

TL;DR

This study demonstrates that fluid flow shear can promote cooperative social behavior in microbial populations by fostering spatial structures that limit cheating, with implications for understanding microbial community dynamics.

Contribution

The paper reveals that shear flow induces self-organizing social structures in microbes through Turing patterns, enhancing cooperation and limiting cheaters.

Findings

Flow shear increases group fragmentation, promoting cooperation.

High shear regions support dense, cooperative microbial populations.

Low shear areas are dominated by opportunistic mutants and lack life.

Abstract

How producers of public goods persist in microbial communities is a major question in evolutionary biology. Cooperation is evolutionarily unstable, since cheating strains can reproduce quicker and take over. Spatial structure has been shown to be a robust mechanism for the evolution of cooperation. Here we study how spatial assortment might emerge from native dynamics and show that fluid flow shear promotes cooperative behavior. Social structures arise naturally from our advection-diffusion-reaction model as self-reproducing Turing patterns. We computationally study the effects of fluid advection on these patterns as a mechanism to enable or enhance social behavior. Our central finding is that flow shear enables and promotes social behavior in microbes by increasing the group fragmentation rate and thereby limiting the spread of cheating strains. Regions of the flow domain with higher shear admit high cooperativity and large population density, whereas low shear regions are devoid of life due to opportunistic mutations.