L. David Mech (“meech”) began his study of these animals at Purdue University as part of a project initiated by Durward Allen. The term “landscape of fear” was first used to describe effects caused by these animals. In a debated example of a top-down trophic cascade, (10[1])these animals facilitated (10[1])the recovery of riparian (10[1])vegetation (10[2])such as willow (10[1])trees and cottonwoods. (10[3])Introgression via interbreeding with a related species is a threat to reintroducing the extirpated “red” (10[1])species (-5[2])of these animals (10[2])in the southeastern (10[1])US. (10[1])The oscillatory (10[1])population cycles of these animals and moose (10[1])are studied in the (10[1])world’s longest running (10[1])predator–prey study on Lake Superior’s Isle Royale. For 10 points, what keystone species and apex predator was reintroduced in the 1990s to Yellowstone (10[1])National Park? ■END■ (10[1])