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natural selection |
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natural selection: see selection selection. In Darwinism , the mechanism of natural selection is considered of major importance in the process of evolution . Popular formulations sometimes envisage a struggle for existence in which direct competition for mates or for various factors in the ..... Click the link for more information. . natural selectionProcess that results in adaptation of an organism to its environment by means of selectively reproducing changes in its genotype. Variations that increase an organism's chances of survival and procreation are preserved and multiplied from generation to generation at the expense of less advantageous variations. As proposed by Charles Darwin, natural selection is the mechanism by which evolution occurs. It may arise from differences in survival, fertility, rate of development, mating success, or any other aspect of the life cycle. Mutation, gene flow, and genetic drift, all of which are random processes, also alter gene abundance. Natural selection moderates the effects of these processes because it multiplies the incidence of beneficial mutations over generations and eliminates harmful ones, since the organisms that carry them leave few or no descendants. See also selection. |
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This fundamental subject of Natural Selection will be treated at some length in the fourth chapter; and we shall then see how Natural Selection almost inevitably causes much Extinction of the less improved forms of life and induces what I have called Divergence of Character. From these and their degraded slaves and a later intermixture of the blood of the anthropoids sprung the gnarled men of Opar; but by some queer freak of fate, aided by natural selection, the old Atlantean strain had remained pure and undegraded in the females descended from a single princess of the royal house of Atlantis who had been in Opar at the time of the great catastrophe. He pointed out-- writing in a foolish, facetious tone--that the perfection of mechanical appliances must ultimately supersede limbs; the perfection of chemical devices, digestion; that such organs as hair, external nose, teeth, ears, and chin were no longer essential parts of the human being, and that the tendency of natural selection would lie in the direction of their steady diminution through the coming ages. |
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natural selection
