COMMUNITY ASSEMBLY

The coming together of species to form a community. In detail, community change involves new arrivals (through speciation events and immigration), the persistence of existing species and species loss (through extinction and emigration). The process of community assembly is individualistic because each species has its own propensity for dispersal and population expansion. Evidence that communities assemble (and disassemble) in this manner is seen in multidirectional ecological succession, in which succession leads in several directions and does not end in a single climax state (see climaxvegetation). It is also seen in no-analogue communities (see modern analogue), such as the temperate grassland biome during the pleistocene, and in ‘disharmonious’ communities such as existed in the southern Great Plains and Texas during the Pleistocene when present-day boreal mammals lived alongside present-day grassland and deciduous forest mammals. The process of community assembly means that community response to global warming is unlikely to involve a simple, zonal shift of biome boundaries.

[See alsoassemblage, community concepts, individualistic concept, island biogeography]