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selection |
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selection. In Darwinism Darwinism, concept of evolution developed in the mid-19th cent. by Charles Robert Darwin . Darwin's meticulously documented observations led him to question the then current belief in special creation of each species. ..... Click the link for more information. , the mechanism of natural selection is considered of major importance in the process of evolution evolution, concept that embodies the belief that existing animals and plants developed by a process of gradual, continuous change from previously existing forms. This theory, also known as descent with modification, constitutes organic evolution. ..... Click the link for more information. . Popular formulations sometimes envisage a struggle for existence in which direct competition for mates or for various factors in the environment (e.g., food, water, and suitable space) counteracts the tendency toward overproduction of plants and animals resulting from the process of reproduction. But there are diverse ways other than direct struggle through which those organisms better adapted to the environment can survive and reproduce more successfully than those less fitted. A special form of natural selection, sexual selection, is also stressed in Darwinism. It attempts to account for secondary sexual characteristics that are not necessarily valuable in the struggle for existence. It assumes that the female selects as a mate one having the most highly developed of such characteristics, e.g., elaborate plumage or superior song, thereby perpetuating those characteristics. However, this interpretation is now questioned by many scientists. Artificial selection, the selection by humans of individuals best suited for their purposes, is common in plant and animal breeding. selectionIn biology, the preferential survival and reproduction or preferential elimination of individuals with certain genotypes, by means of natural or artificial controlling factors. The theory of evolution by natural selection was proposed by Charles Darwin and Alfred Russel Wallace in 1858. Artificial selection differs from natural selection in that inherited variations in a species are manipulated by humans through controlled breeding in order to create qualities economically or aesthetically desirable to humans, rather than useful to the organism in its natural environment. selection Biology the natural or artificial process by which certain organisms or characters are reproduced and perpetuated in the species in preference to others selection [si′lek·shən] (communications) The process of addressing a call to a specific station in a selective calling system. (genetics) Any natural or artificial process which favors the survival and propagation of individuals of a given phenotype in a population. How to thank TFD for its existence? Tell a friend about us, add a link to this page, add the site to iGoogle, or visit webmaster's page for free fun content. |
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We shall thus see that a large amount of hereditary modification is at least possible, and, what is equally or more important, we shall see how great is the power of man in accumulating by his Selection successive slight variations. I have written the present volume because I have found no other that, to my mind, combines satisfactory accomplishment of these ends with a selection of authors sufficiently limited for clearness and with adequate accuracy and fulness of details, biographical and other. That lady seemed at a loss to make a selection, but finally settled upon a stick of nougat, wondering if it were not too rich; whether it could possibly hurt her. |
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