density-dependent factor


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density-dependent factor

any factor that regulates the size of a population under natural circumstances by acting more severely on a population when it is large than when it is small. Thus as numbers increase so does competition for resources, e.g. food or nesting material. Such factors can affect either the birth rate or the mortality, but the latter is more usual. At high densities of populations some organisms have fewer young, or the mortality rate (brought about by predation, disease or food shortage) might be higher than at low densities. The factors tend to cause population numbers to be maintained at a relatively constant level over long periods of time. See CONTROL, REGULATION (2). Compare DENSITY-INDEPENDENT FACTOR.