Evaluating the risks and benefits of assisted migration in a stochastic metacommunity

Dr Gregory Backus1, Dr Marissa Baskett1

1University Of California, Davis, Davis, United States

With projected rates of climate change, species that are dispersal-limited and species with narrow thermal tolerance will be especially at risk of extinction. A proposed approach for conserving these climate-threatened species is assisted migration, where populations are moved beyond their historical ranges to locations expected to be more suitable in future climates. Assisted migration has been controversial because it presents novel risks for both the target species and the recipient ecological community. Among these risks, relocating a threatened population to the wrong place at the wrong time could mean that the population fails to establish, lowering the probability of the species persisting in the long run. We built a stochastic metacommunity model to simulate several species competing on a one-dimensional temperature gradient undergoing climate change. With this model, we simulated assisted migration in randomized metacommunities, varying the type of species moved, the proportion of the population moved, and the estimate of the optimal target location. We found that assisted migration increased a species’ persistence probability most when relocating an intermediate proportion of the population, even if the left-behind portion of the population was unlikely to survive in the long run. The left-behind population could serve as a “safety net” for misjudged assisted migration attempts, allowing managers to try again. We also found that assisted migration generally increased persistence of most species except for those with narrow thermal tolerance breadth. This suggests a need to develop alternative management strategies for conserving species limited by narrow thermal tolerance.


Greg is a postdoctoral scholar at the University of California, Davis. He uses ecological theory and mathematical modeling to study emerging controversial topics in conservation biology and ecology.

Similar Posts