A certain species of animal represents just 3% of the biomass in its ecosystem. We might classify this as a keystone species if its removal
A) caused plant biomass to increase by 5%.
B) caused 2% of the other species in the community to disappear.
C) caused the diversity of the plant community to decline by 40%.
D) allowed an even rarer species to increase in number and take its place.
E) had no effect on the community.

Question

Quizplus · Accepted Answer

Keystone species have a disproportionately large effect on their environment relative to their abundance. The significant decline in plant community diversity (40%) upon the removal of this species indicates its crucial role in maintaining ecosystem structure, thus classifying it as a keystone species.

A Certain Species of Animal Represents Just 3% of the Biomass