Practice question

High competition can reduce reproductive output because individuals must spend limited energy obtaining food, defending territories, or tolerating interference rather than producing and provisioning offspring. Resource limitation may also delay maturity or cause embryos and juveniles to be lost. Low population size can suppress reproduction through an Allee effect, so the wording is broad, but within standard high-density regulation the keyed mechanism is competition. Population regulation concerns feedback, not mere limitation. A drought may sharply reduce numbers yet fail to push the population toward a repeatable equilibrium. Competition, disease, territoriality, and some predator responses can strengthen with crowding, changing births or deaths in a direction that opposes the density change and thereby producing regulation. Reading the terms biologically, rather than memorizing labels, shows how individual survival and reproduction scale up to population change. Ecological predictions remain conditional on the stated environment, because changing resources, mortality, or interactions can alter the observed demographic pattern.