What role do keystone species like wolves play in their ecosystems, and how has their reintroduction into areas like Yellowstone National Park impacted the environment?

Keystone species, such as wolves (Canis lupus), have a disproportionately large impact on their ecosystems relative to their abundance. Wolves help regulate prey populations, such as elk, which in turn affects vegetation and the overall health of the ecosystem. The reintroduction of wolves into Yellowstone National Park has led to a reduction in elk populations, allowing for the recovery of vegetation, improved stream habitats, and increased biodiversity as other species benefited from the changes in the environment.