Speaker
Description
The rescue effect is a well-known process in spatial ecology where immigration from a subsidizing subpopulation prevents a vulnerable subpopulation from going extinct. It has become a cornerstone of metapopulation theory and provides a conceptual basis for conservation management.
In this talk, we challenge the prevailing optimism surrounding dispersal. We uncover the phenomenon of the failed rescue effect, where increased dispersal drives both the source and target subpopulations toward joint extinction. We demonstrate this in a two-patch metapopulation model with explicit local population dynamics that are subject to a strong Allee effect. The failed rescue effect occurs when staggering emigration depletes the source patch while the resulting immigration remains insufficient to lift the target patch above its critical threshold. Furthermore, we refine the typology of successful rescue effects, distinguishing between sustenance rescue, which maintains a vulnerable subpopulation at low abundance, and super rescue, which boosts the subpopulation beyond its Allee threshold to a high-abundance stable state.
By integrating local non-linear dynamics with spatial coupling, our analysis reveals that metapopulations with Allee effects may be far more fragile than previously assumed, offering a novel perspective on the risks of connectedness in spatial ecology.
