Speciation

An adaptive radiation is a burst of evolution, creating several new species out of a single parent species. A population of species, 1, moves into a new habitat and establishes itself in a niche, or role, in that habitat. While there, it adapts to its new environment and becomes different from the parent species. Next, a new population of the parent species, 2, moves into the area, trying to occupy the same niche as 1. Because of the niche rule, which states that only one of a group of closely related species may occupy the a niche in a given habitat, competition between 1 and 2 places pressure on both groups to adapt to separate niches. In this process, each becomes further distinguished from each other and the parent species. A third or even more populations of the parent species may move into the area, causing several different species to arise from the same parent species.

Adaptive radiations create many new species out of a single species in a relatively short period of time. If all speciation took place by creating one or two new species out of a parent species, we would not expect to see the number of species we do today.

The Niche Rule states that no two closely related species may occupy the same niche in a given habitat. Competition between the two species will be so intense that each will evolve to be different from the other and able to occupy a different niche.