Population Growth

Chicago park lake

In ecology, a population is a group of individual organisms belonging to the same single species which inhabit a specific area. The chimpanzees of Uganda’s Congo River are a population. So are the chimpanzees of western Tanzania. Though both of these groups belong to the same species, they should be considered separate populations because they do not inhabit the same specific area.

When surveying the populations of an ecosystem, researchers may be motivated to answer questions such as: what is the average population size? How does the average population size change over time?

To understand how population sizes vary through time, four relevant factors should be kept in mind: 1) the birth rate of the individual organisms, 2) their death rates 3) the introduction of nonnative individuals that have migrated from a separate population, 4) the removal of individuals that migrate out of the population being observed. Using these four measures provides insight into the rate of change within a population.

Populations may have a steady rate of growth, grow exponentially or even grow exponentially up until a certain point. A population’s growth may slow, or be halted completely by environmental factors, such as the presence of predator species or the lack of resources necessary for survival.