Abstract
Assisted migration is the translocation of species beyond their historical range to locations that are expected to be more suitable under future climate change. However, a relocated population might fail to establish within its donor community if there is high uncertainty in decision making, climate, and interactions with the recipient ecological community. To quantify the benefit to persistence and risk of establishment failure of assisted migration under different management scenarios, we built a stochastic metacommunity model to simulate several species reproducing, dispersing, and competing on a temperature gradient as temperature increases over time. Without assisted migration, the species in our model were vulnerable to climate change if they had low population sizes, short dispersal, and strong poleword competition. When relocating species that exemplified these traits, assisted migration increased the long-term persistence of the species most when relocating a fraction of the donor population, even if the remaining population was very small or rapidly declining. This suggests that leaving behind a fraction of the population could be a robust approach, allowing managers to repeat assisted migration in case they move the species at the wrong place and wrong time, especially when it is difficult to identify a species’ optimal climate. We found that assisted migration was most beneficial to species with low dispersal ability and least beneficial to species with narrow thermal tolerances, for which assisted migration increased extinction risk on average. Lastly, while relocation did not affect the persistence of non-target species in our simple competitive model, researchers will need to consider a more complete set of community interactions to comprehensively understand invasion potential.
Competing Interest Statement
The authors have declared no competing interest.
Footnotes
Changed the title to focus on competition. Edited the abstract to highlight our limitations and stress that invasion might occur in more complicated systems. Edited the introduction to describe more of the risks and benefits of assisted migration. Edited methods to described substantial biological limitations. Added a figure to visualize claims about spreading out negative density dependence between two smaller populations during fractional relocation. Edited the discussion of invasiveness to clarify that we are not suggesting that invasion will not occur, but instead that we are suggesting that more complex ecological dynamics are necessary to see substantial effects of invasion.