By now, plenty of people have heard of the effect reintroducing wolves had on the ecosystem in Yellowstone National Park: more wolves means fewer elk and deer hanging out by streams, so plants like willows grow taller. Wolves get credit as ecosystem engineers.
A recent study shows that cougars may have a similar effect in the same area. And it gets even more interesting, because cougars leaving meals behind (dead deer) has allowed for growth in beetle populations.
Joshua Barry and Mark Elbroch were members of the research team for Panthera, the wild cat conservation organization.