G.F Gause is a Russian biologist. According to him “Adaptive radiation is characterized by replacement of one form of organism by another form of organism consequent on their inability to share the same ecological niche for an indefinite period of time due to inherent differences in competitive ability and rates of reproduction”. That means “the species with identical ecological requirements cannot occupy the same ecological niche for long time and hence less competent species may either be driven away or becomes extinct.
Gause’s Rule is also called competitive exclusion principle. It emphasizes that adaptive radiation is evolution in several specialized directions starting from one common and generalized ancestral type, or the entry of the organisms of the original stock to new adaptive zones. In other words, closely related groups exhibit great divergence in their morphology when they are found in different habitats (divergence). Thus, adaptive radiation.
- Replaces one form organism by another form of organism.
- Prepare different forms of organisms to occupy different eco niches
- Enables different forms of organisms to acquire different competitive abilities
- Endows different forms of organisms with different rates of reproduction success
Prosimi evolved into old world monkeys and new world monkeys. New World monkeys or platyrrhines, one of the three major primate clades, constitute an example of a major mammalian adaptive radiation that unfolded in isolation in Central and South America during the last 25–35 Ma, resulting in broad ecological and morphological diversity
The diversity of Galapagos finches, results from adaptive radiation. During the course of evolution, their beaks have changed in size and morphology so that they are now adapted to different diets: some species eat mostly animals (e.g. insects), others seeds or plants; some feed in the trees, and others on the ground. Ultimately, it is the variety of environments and food resources that led to the rapid differentiation of these species of finches. All these species share a common ancestor and are now characterized by broad ecological (their diets are different) and morphological (the size and shape of their beaks are different) diversity.
The genus Australopithecus is a collection of hominin species that span the time period from 4.18 to about 2 million years ago. Australopiths were terrestrial bipedal ape-like animals that had large chewing teeth with thick enamel caps, but whose brains were only very slightly larger than those of great apes. They are the closest known relatives of our genus Homo, and we most likely evolved from a species that was part of this adaptive radiation. They are similar to the group of animals referred to as Paranthropus by some authors, or “robust” australopiths by others , but have less extreme adaptations for powerful chewing.
Evidence showing that the competitive exclusion principle operates in human groups. For example, hunter-gatherer groups surrounded by other hunter-gatherer groups in the same ecological niche will fight, at least occasionally, while hunter-gatherer groups surrounded by groups with a different means of subsistence can coexist peacefully.