"They provide an essential part of the food chain, and help prevent overpopulation of their prey by killing off the weaker members of their prey's herd, thus ensuring that only those prey who are the fittest to survive do survive"@en . "They provide an essential part of the food chain, and help prevent overpopulation of their prey by killing off the weaker members of their prey's herd, thus ensuring that only those prey who are the fittest to survive do survive"@en . . "What do lions provide for the ecosystem"@en . .