Population Regulation

All animal populations carry an inherent tendency to keep increasing in number, but no population increases without limit. Once a population reaches the carrying capacity of its environment, its numbers stop climbing and instead remain roughly static or fluctuate in response to changing environmental conditions — a process called population regulation. The factors that regulate population size fall into two broad categories: density-independent (extrinsic) factors, which act on a population regardless of how crowded it already is — availability of space, shelter, weather, and food supply are the chapter's examples — and density-dependent (intrinsic) factors, whose effect intensifies as the population becomes more crowded — competition, predation, emigration, immigration and disease ar …