Speaker
Description
Mutation provides the raw material for evolution. Mutation rates thus tune evolvability, the ability to undergo adaptive evolution: if mutation rates are too low, evolution is impeded; if mutation rates are too high, adaptive traits cannot be maintained. Empirical studies have demonstrated that mutation rates may change with individual condition, for instance in the case of stress-induced mutagenesis in bacteria, which is implicated in the evolution of antibiotic resistance. However, it is not clear if a stress-induced increase in mutation rate is an adaptive response which enhances evolvability by increasing the influx of mutations in times of stress, or if it is a (potentially mal-adaptive) byproduct of stress itself. Moreover, while empirical evidence of condition-dependent (i.e., plastic) mutation rates is accumulating, theoretical models studying their evolution are lacking. Here, we employ an individual-based simulation approach to examine the evolution of condition-dependent mutation rates in a changing environment. We show that condition-dependent mutation rates readily evolve, providing “well-timed” variation specifically when organisms are poorly adapted. Such plastic mutation rates facilitate better adaptation to changing environments, and their evolution provides an example of evolvability itself evolving.
