A) Primary succession
B) Regulation
C) Secondary succession
D) Determination

A) A mountain lion preys upon deer and as a result the abundance of a grass species dramatically increases.
B) A large population of European rabbits grazes on an annual weed species and dramatically reduces their population.
C) A marine mammal feeds on baleen and significantly reduces their abundance in the Pacific Ocean.
D) A plant virus reduces the number of native plants in a community.

A) Species are competitively equivalent. As a result, all species colonize a site and maintain their presence. Thus, species richness is high.
B) Species are not competitively equivalent. This means that some species will be able to colonize a site and maintain their presence, but some will not be able to do so.
C) Species can either be early species or later species, but ultimately regardless of which type of colonizer they are, each will be competitively equivalent.
D) Primary dominance is determined by density-dependent factors. As a result, the species richness is high.