Disturbance regime alters the impact of dispersal on alpha and beta diversity in a temporary rock pool metacommunity

Background/Question/Methods

Disturbance and dispersal are two fundamental ecological processes that shape local and regional diversity patterns, yet their interaction and the underlying mechanisms are still poorly understood and evidence from natural systems is particularly lacking. Using an invertebrate rock pool metacommunity as a natural model system, we studied potential synergistic effects of disturbance regime and patch isolation on diversity patterns of organisms with contrasting dispersal modes (passive vs. active dispersal).

Results/Conclusions

Isolation and disturbance had negative synergistic effects on alpha diversity; both directly, by excluding late successional species from isolated patches; and indirectly, by modulating establishment success of generalist predators in well connected patches. Unimodal relationships between isolation and alpha diversity, as predicted by mass effects, were only detected for passive dispersers in highly disturbed patches and not in active dispersers. For passive dispersers, a positive synergistic effect of isolation and disturbance on beta diversity was found, presumably due to differences in deterministic succession and stochastic colonization-extinction dynamics among different patch types. Our findings illustrate that interactions between dispersal rates and disturbance regime can be important for explaining species diversity patterns in metacommunities and support the idea that diversity in disturbed habitats may be more sensitive to potential adverse effects of too little or too much dispersal.