Evolutionary rescue of communities under nonlinear environmental change
Due to unprecedented rapid global change, ecological communities are currently experiencing abrupt and sustained environmental stress. Populations and communities that cannot migrate or adapt physiologically may be extirpated. In a previous mathematical modeling study (Fussmann & Gonzalez 2013) we analyzed the rescue potential of three-species communities under linear, unidirectional environmental change. We found that trait evolution can allow community evolutionary rescue and ensure the community persists. We were also able to show that a change in the character of community oscillations may be a signature that a community is undergoing evolutionary rescue. Here, I extend this framework to environmental change signals that are nonlinear and/or cyclical.
Fluctuating environmental dynamics present conditions that make it difficult for trait evolution to “lock in” to an adaptive state that leads to long-term fitness increases of some or all populations that comprise the community. Community evolutionary rescue is less likely under these conditions than under the comparatively predictive conditions of linearly changing environments. Of particular interest are conditions of currently observed global environmental change, characterized by a trend that is obscured by an additional cyclical or stochastic component. Under these conditions, evolutionary rescue potential tends to depend on the relative strength of linear and nonlinear signals.