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

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.

Which of these species is a keystone species?

(1 point)
Responses

elk
elk

bears
bears

wolves
wolves

willows

Answer 1

Wolves are the keystone species in this scenario. Keystone species play a critical role in maintaining the structure of an ecological community. The reintroduction of wolves to Yellowstone helped regulate the elk population, which in turn allowed for the recovery of willow trees and affected the entire ecosystem, including the populations of other species such as beavers.