Community Ecology 2 - Predation and Community Flashcards
Species Diversity in a Community
- Richness
- Evenness
Species Richness (S)
simply a count of the number of species in a community
Species Evenness
the relative abundance of species in a community (how evenly individuals are distributed among species)
Community Stability
- communities are not random assemblages of species
- they are non-random because of interspecific interactions
Keystone Species
species on which other species in an ecosystem largely depend, such that if it were removed the ecosystem would change drastically
- serves as an unintentional force for stability of a complex set of community interactions
- usually neither the most numerous nor best competitor for resources in an ecosystem
MacArthur + Wilson: Islands
- more isolated island have lower immigration rates
- larger islands have lower “extinction” rates (loss of the species to the island). One way that a species can remain on the island is to re-migrate, which is more likely to happen by change on larger islands
Equilibrium Number - S-hat
the intersection of immigration and extinction rates for an island predict an equilibrium number of species, S-hat, assuming island size and distance from mainland