Metacommunities: Spatial Community Ecology

Abstract

AbstractEcology explains the distribution and abundance of species from small to large spatial scales. Explanations based only on processes operating at local scales do not fully account for patterns of diversity at regional scales. Recent decades have seen the unification of local and regional processes as explanations for the maintenance of diversity within the metacommunity concept. A metacommunity is a set of local communities connected by dispersal of multiple potentially interacting species. Metacommunity ecology studies the interactions among species as they occur across a network of patches. The rate and frequency of dispersal mediates the spatial distribution of diversity, abundance and the flux of energy across the metacommunity. The metacommunity concept also provides a deeper understanding of the causes and consequences of species loss, and suggests solutions to mitigate these effects.Key conceptsConcept: SummaryColonization: A spatial process in which a population becomes established in an area where it was previously absent.Open community: A community that experiences immigration and emigration.Metacommunity dynamics: The dynamics of species abundances and distribution within a metacommunity due to the compound effects of species interactions and dispersal.Local versus regional processes: Local processes occur within a community and include density‐dependent growth and interspecific interactions, whereas regional processes occur across communities and include dispersal.Source–sink system: A network of patches of a single species connected by dispersal containing two categories of population types: (1) source populations, in which the birth rate exceeds the death rate and emigration is common and (2) sink populations, in which the death rate exceeds the birth rate and frequent immigration is required to sustain the presence of individuals.Rescue effect: A spatial process in which local extinction is prevented by immigration from other patches in the metacommunity. The rate of immigration per patch increases as the proportion of patches occupied increases.Neutral model: All species are assumed to be identical with respect to their birth and death rates (fitness). Stabilizing mechanisms are absent, and the abundances of all species drift randomly to extinction. Diversity is maintained in the long‐term by speciation.Extinction debt: The delayed loss of species that occurs long after the initial loss of habitat connectivity.Spatial insurance hypothesis: The dispersal‐dependent maintenance of biodiversity and ecosystem processes within a metacommunity.