Problem : Describe the mechanism of adaptive radiation.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.
Problem : How does adaptive radiation help account for the diversity of life on earth?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.
Problem : Explain the Niche Rule.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.