POPULATION GROWTH

A second key characteristic of any population is its capacity to grow. Most populations tend to remain relatively constant in number, regardless of how many offspring the individuals produce. Darwin partly based his theory of natural selection on this seeming contradiction. Many calculations have been done, showing, for example, that houseflies, bacteria, or even elephants would soon cover the world if their reproduction were unchecked. Under certain circumstances, however, a population size can increase rapidly for a time. We must consider, what these circumstances are and what factors operate in nature to limit population growth.