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, these animals facilitated the recovery of riparian vegetation such as willow trees and cottonwoods. Introgression via interbreeding with a related species is a threat to reintroducing the extirpated “red” species (-5[1])of these animals in the southeastern US. The oscillatory population cycles of these animals and moose are studied in the world’s longest running 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 National Park? ■END■ (10[1])