Wolves were reintroduced to Yellowstone National Park in 1995. They began to hunt the abundant elk population, so elk numbers decreased. The elk carcasses provided food for other predators, like foxes, coyotes, and bears, so all of their populations increased. Elk used to overgraze on willow plants; now that willows are growing back, beaver numbers are increasing, because they prefer the slow-moving water that willows cause.

Question

Which of these species is a keystone species?

(1 point)
Responses

wolves
wolves

bears
bears

elk
elk

willows

Answer 1

The correct answer is wolves.

Wolves are considered a keystone species because their presence has a significant positive impact on the ecosystem. By controlling the elk population, they help prevent overgrazing of vegetation, which in turn supports a diverse range of species, including willows, beavers, and various other plants and animals in the ecosystem.