Can dispersal rescue metacommunities from extinction cascades?

• Climate change and habitat loss are increasingly affecting the structure and dynamics of ecological communities both at the local and regional scale. Changes in the spatial structure of landscapes as well as in the trophic structure of local communities can be expected to have important consequences for the long-term persistence of species in metacommunities. The aim of the present work is to investigate how the spatial structure of the landscape (patch density) and dispersal patterns of species (migration rate and dispersal distance) affect a metacommunities response to local loss of species and to increased mortality of individuals during dispersal. Using a spatially and dynamically explicit metacommunity model we find that the effect of dispersal on metacommunity persistence is two-sided: on the one hand, when dispersal involves no risk, high migration rate significantly reduces the risk of bottom-up extinction cascades following the local removal of a species. The explanation for this is that recolonization rates of the locally removed species increases with increasing migration rate. On the other hand, when dispersal imposes a risk to the dispersing individuals, high migration rate increases extinction risks, especially when dispersal is global (long dispersal distances). Largebodied species with long generation times at the highest trophic level are particularly vulnerable to extinction when dispersal involves a risk. These results suggest that decreasing the mortality risk of dispersing individuals by improving the quality of the habitat matrix might greatly increase the robustness of metacommunities to local loss of species by enhancing recolonizations and rescue effects.

Nyckelord

Dispersal

extinction cascades

food web

metacommunity

recolonization

resque effect

spatial model

species extinctions

Publikations- och innehållstyp

vet (ämneskategori)

ovr (ämneskategori)