Metacommunities

Abstract

Metacommunities consist of collections of local communities linked by dispersal of multiple interacting species. Unlike traditional community ecology, the metacommunity concept acknowledges that dispersal may alter community structure. Additionally the concept permits that both local and regional processes modify species diversity. Metacommunities have applied relevance for understanding factors like habitat fragmentation, and for improving conservation. Four models have been described that capture a variety of dynamics that could contribute to species diversity: neutral community models where all species are equal and diversity is maintained by localized dispersal and speciation; species sorting emphasizing spatial niches; mass effects emphasizing the movement of individuals from good to poor habitats; and patch dynamics emphasizing trade-offs in species traits in patchily-distributed but otherwise uniform environments. Most frequently in empirical systems species sorting and mass effects are found, whereas patch dynamics appear less common. Neutral models lack adequate empirical support but elements of their transient dynamics and stochasticity could be present. Metacommunity structure could predict the response of communities to altered productivity, and how fragmentation influences the abundance of different trophic levels. It has been shown that metacommunity structure can alter the functioning of ecosystems. Finally, we discuss how a metacommunity structure could alter the potential for evolution.