Controlling social evolution of microbial populations

Many species of microbes cooperate by producing "public goods" from which they collectively benefit. However, these groups are under the risk of being taken over by cheating mutants that do not contribute to the pool of public goods. Here we present theoretical findings that address how social evolution of microbes can be manipulated by external perturbations, to either prevent or promote the fixation of cheaters. To control group reproduction rate and group size, we determine the effects of fluid dynamical properties such as flow rate or boundary geometry. We also study the social evolutionary consequences of introducing beneficial or harmful chemicals at steady state and in a time dependent fashion. We show that by modulating the flow rate and by applying pulsed chemical signals, we can modulate the spatial structure and dynamics of the groups, in a way that can select for more or less cooperative microbial populations.