  Bacterial chemotaxis systems are as diverse as the environments that bacteria
inhabit, but how much environmental variation can cells tolerate with a single
system? Diversification of a single chemotaxis system could serve as an
alternative, or even evolutionary stepping-stone, to switching between multiple
systems. We hypothesized that mutations in gene regulation could lead to
heritable control of chemotactic diversity. By simulating foraging and
colonization of E. coli using a single-cell chemotaxis model, we found that
different environments selected for different behaviors. The resulting
trade-offs show that populations facing diverse environments would ideally
diversify behaviors when time for navigation is limited. We show that
advantageous diversity can arise from changes in the distribution of protein
levels among individuals, which could occur through mutations in gene
regulation. We propose experiments to test our prediction that chemotactic
diversity in a clonal population could be a selectable trait that enables
adaptation to environmental variability.
