Question

A keystone species: a. is usually a primary producer. b. has a critically important role in determining the species composition of its community. c. is always a predator. d. usually reduces the species diversity in a community. e. usually exhibits aposematic coloration.

Short answer

The correct answer is option b: A keystone species has a critically important role in determining the species composition of its community.

Step-by-step solution

Understanding Key Concepts

A 'keystone species' in an ecosystem is a species on which other species largely depend, and whose removal could significantly alter the ecosystem. Despite being relatively low in numbers, keystone species have a big influence on an ecosystem's biodiversity and health.

Applying the Definition

Now that the concept of a keystone species is understood, one can see that it isn't necessarily a primary producer, predator, reducer of species diversity or a possessor of aposematic coloration.

Selection of Correct Option

By applying the understanding from step 2, it becomes clear that option 'b' is the most fitting. A keystone species indeed plays a critical role in shaping the species composition within its community. Should a keystone species be removed, the entire food web and community could be disrupted, leading potentially to loss of biodiversity.