AP biology: community ecology

Species richness

Listing of the species within a community; it does not reveal the relative abundance of organisms

Species diversity

Includes a listing of the species in a community and the abundance of each species

Keystone species

An organism that plays a unique and crucial role in the way an ecosystem functions. W/o this species the ecosystem would be dramatically different or cease to exist altogether

Intraspecific competition

Between members of the same species

Interspecific competition

between members of different species

Mutualism

Benefits both members of the relationship

Obligate symbionts

Both organisms entirely depend on each other for survival

Commensalism

benefits one organism, the other organism is not affected

Parasitism

Benefits one organism, harms the other organism

competitive exclusion

no two species can indefinitely occupy the same niche at the same time

Resource partitioning

when species shift niches; they no longer directly compete

Ecological succession

The predictable and orderly changes in the composition or structure of an ecological community

Pioneer species

The first species to appear during succession

Climax community

The stable, mature community where there is little change in the compsition of species

Primary succession

There is no soil already established, might occur on bare rock or after a landslide, when there is no soil

Secondary succession

Occurs when there is a disturbance but the soil is still intact, might occur after a fire, flood or logging