Accelerating demographic rates can bolster evolutionary rescue in warming environments

Background/Question/Methods

Much of the theory investigating evolutionary rescue has ignored the ecological impacts that challenging environmental conditions will have on individuals and populations. While feedbacks between ecology and evolution have garnered much attention recently, there has been little work highlighting how this interplay may influence the potential for evolutionary rescue from environmental change. Early contributors to the study of evolutionary rescue identified four key elements that determine the success or failure of a population to persist via evolution in a changing environment: the initial population size, the amount of heritable variation in key traits, and the rate and severity of environmental change. While these elements have been explored as tunable parameters in models, few studies have recognized the potential for eco-evolutionary feedbacks to alter these elements over the course of an environmental challenge.

Results/Conclusions

Using a stochastic birth-death model where the rates of birth and death scale with temperature according to empirically-derived relationships for microbes, we demonstrate the potential for accelerating demographic rates to bolster evolutionary rescue as temperatures increases. This occurs because mutants whose phenotype is a better match to the warming environment may also exhibit faster rates of birth and death, leading to an acceleration in the per-capita response to selection as the environment warms. We show that this acceleration can partially compensate for the rapid decrease in the number of births that occurs during the early phase of an evolutionary rescue when population size is in decline. Given that increasing turnover is a general prediction for warming across a broad range of systems, accelerating demographic rates may allow evolutionary rescue to occur where it was previously considered to be unlikely.