Natural selection

:For the computer game, see Natural Selection (computer game).

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Natural selection is a process by which biological populations are altered over time, as a result of the propagation of heritable traits that affect the capacity of individual organisms to survive and reproduce. It is one of several mechanisms that give rise to the evolution of biological species (other mechanisms include genetic drift and gene flow.) However, natural selection has a special significance because it is believed to be the one responsible for organisms being adapted to their environment. The theory of natural selection was proposed by Charles Darwin and Alfred Russel Wallace in 1858, though vaguer and more obscure formulations had been arrived at by earlier workers.

Related Topics:
Biological - Population - Heritable traits - Organism - Reproduce - Evolution - Species - Genetic drift - Gene flow - Adapted - Charles Darwin - Alfred Russel Wallace - 1858

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Natural selection can be subdivided into two types: (i) ecological selection, which arises from the portion of an organism's environment not related to direct sexual competition (such as the availability of food, the presence of predators, and so forth); and (ii) sexual selection, which arises from the competition for mates between individuals of the same sex. The reason for this division is that the effects of sexual selection can produce results that seem counterintuitive from the point of view of ecological selection alone (a famous example being the tails of peacocks, which, though cumbersome, serve an important purpose in courtship displays.)

Related Topics:
Ecological selection - Food - Predator - Sexual selection - Peacock - Courtship

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Natural selection is distinguished from artificial selection, which is the alteration of domesticated species resulting from human intervention as opposed the "natural environment". However, the mechanisms of natural and artificial selection are essentially identical, and in fact the observed effects of artificial selection were used by Darwin to illustrate how natural selection works.

Related Topics:
Artificial selection - Domesticated - Human

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The modern theory of natural selection is formulated in terms of genetic differences between individuals, resulting in differences in the frequency of alleles in a population over successive generations. The genetic variation on which natural selection acts are now understood to arise from random mutations.

Related Topics:
Genetic - Allele - Genetic variation - Mutation

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