Competition between coexisting species can be either direct or indirect.In which of these examples is the competition indirect (exploitative)?
A) Several species of Galápagos finches vary in beak size and eat different-sized seeds.
B) Plants produce many nitrogen-absorbing roots, reducing nitrogen available for nearby plants.
C) Bullfrogs eat almost anything smaller, including other frogs, thus removing their competition.
D) Tadpoles live in the water and feed on algae; when they become frogs, they feed on insects.
E) Chipmunks and squirrels live in the same areas and compete for acorns but not for nesting sites.

Question

Quizplus · Accepted Answer

In option B, plants are competing for limited resources, specifically nitrogen, through an indirect mechanism of resource depletion. This is exploitative competition where one species indirectly reduces the resources available to another species without directly interacting with them. In all other options, the competition is direct, such as consumption of the same food or occupying the same habitat, and hence not indirect.

Competition Between Coexisting Species Can Be Either Direct or Indirect