A close and often lifelong ecological relationship between species is calledMultiple choice question.succession.species richness.a keystone.a symbiosis.

A gradual change in the species composition of a community over time is termedMultiple choice question.succession.species richness.species evenness.commensalism.

Succession occurs whenMultiple choice question.a keystone species is removed.one species is harmed while another benefits.a chemical becomes more concentrated in organisms at higher levels in the food chain.a community's species composition gradually changes over time.

An organism's niche includes its habitat, its resource requirements, and itsMultiple choice question.abundance.evolutionary relationship to other species.potential for gene flow.place in the food chain.

The greatest threat to biodiversity isMultiple choice question.overharvesting.secondary succession.introduced species.habitat destruction.

Members of the same species that inhabit the same area are called aMultiple choice question.habitat.community.population.niche.