A well known observation of ecology is the change in populations of predator and prey. When more predators are introduced to an environment, they eat more prey animals. This tends to increase the population of predators, since they get more food and can thus live longer to reproduce more. But it also reduces the food supply, which contrariwise causes the predators to live shorter lives and to reproduce less. In some ecosystems, the populations of predator and prey cycle up and down wildly, but usually they reach an equilibrium.<ref>Rockwood, Larry L. ''Introduction to Population Ecology''. Wiley Blackwell, 2006. ISBN 9781405132633. Chapter 10.</ref> | A well known observation of ecology is the change in populations of predator and prey. When more predators are introduced to an environment, they eat more prey animals. This tends to increase the population of predators, since they get more food and can thus live longer to reproduce more. But it also reduces the food supply, which contrariwise causes the predators to live shorter lives and to reproduce less. In some ecosystems, the populations of predator and prey cycle up and down wildly, but usually they reach an equilibrium.<ref>Rockwood, Larry L. ''Introduction to Population Ecology''. Wiley Blackwell, 2006. ISBN 9781405132633. Chapter 10.</ref> |