How Resource Partitioning Preserves Species

Nature uses resource partitioning as a clever way to allow species seeking the same resources to thrive side by side in the same habitat. Rather than trying to build a relationship in which they split the habitat’s resources in equal halves—humans have a difficult time doing this also—each species evolves traits for using the resources in a way that will not threaten its competitor. For example, hawks and owls both live as predators at the top of their food chain and hunt rodents (rats, mice, voles, squirrels, etc.), small mammals (skunks, rabbits, gophers, etc.), small birds, snakes, and amphibians. To partition these food resources, hawks hunt during the day and owls hunt at night.

Resource partitioning comes about not by choice but through a genetic change in the species so that it develops a trait favorable in its new niche. This occurs over a time period long enough to allow natural selection for favorable traits, a process called adaptation. Adaptations may be physical features, physiological processes, or behavioral characteristics. In 1859 British naturalist Charles Darwin described the process by which species either survive through natural selection or disappear because they cannot adapt to changes in their environment. In his book On the Origin of Species, Darwin wrote, “Though Nature grants long periods of time for the work of natural selection, she does not grant an indefinite period; for as all organic beings are striving to seize on each place in the economy of nature, if any one species does not become modified and improved in a corresponding degree with its competitors, it will be exterminated.” Competition initiates natural selection, which gives rise to adaptations that in turn enable resource partitioning.

Individuals that develop traits allowing them to partition resources occupy a new niche for their species, and the next generations may do the same. Eventually an entirely new species, or subspecies, fills the new niche. This process of filling new niches over generations is called adaptive radiation, and it is the main reason for biodiversity on Earth today.