Longevity hinders evolutionary rescue through slower growth but not necessarily slower adaptation

Abstract

"Evolutionary rescue" is the process by which a population experiencing severe environmental change avoids extinction through adaptation. Theory and empirical work typically focus on short life histories with non-overlapping generations, leaving longevitys effects on rescue relatively understudied. Recent models demonstrate that longevity can inhibit rescue through slower phenotypic evolution but have assumptions that may not generalize across life histories. We built a model integrating evolutionary rescue with concepts from life-history theory, particularly the fast-slow pace-of-life continuum. Longevity is modeled by the balance of survival and reproduction with selection acting on survival, allowing for multiple selection episodes throughout the lifespan. We used this model to simulate three life-history strategies along the fast-slow continuum responding to sudden environmental change. Under nearly all simulated conditions, higher longevities (slower pace of life) resulted in more time at low density and increased extinctions. With perfect trait heritability, rates of adaptation were nearly identical across longevities. But at lower heritabilities, longevity allowed for repeated selection and decoupling of mean genotypes and phenotypes, producing a transient phase of rapid phenotypic change. Our results demonstrate that prior findings that longevity slows adaptation do not hold in all cases and are relevant to long-lived conservation targets.