Rapid evolution slows extinctions in food webs

Historically, evolutionary changes have been thought to act on much longer time scales than ecological dynamics. However, a recent body of research has demonstrated that evolution that is rapid enough to dramatically affect ecological dynamics can lead to feedbacks between ecological and evolutionary processes. Thus, to understand the stability of ecological communities, we must also consider evolutionary change in the component species. Here, we use individual-based simulations of a quantitative genetic eco-evolutionary model to describe how trait evolution influences the stability of ecological communities. On short time scales, faster evolutionary rates decreased the probability of species extinctions as populations at low densities were rescued via trait evolution. However, on longer time scales, evolutionary had little effect on the number of extinctions. The extent of short-term evolutionary rescue depended on the source of trait variation; populations with variation generated through mutation experienced more rescue events and were less prone to extinction, relative to populations with only standing trait variation. Trait evolution leading to more rescued populations increased the stability of the community on timescales relevant to conservation. Our work highlights the importance of intraspecific trait variation and the evolutionary mechanisms maintaining this variation for community ecology, as well as management of declining populations in a community context.