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natural selection |
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selection /se·lec·tion/ (sĕ-lek´shun) the play of forces that determines the relative reproductive performance of the various genotypes in a population. directional selection selection favoring individuals at one extreme of the distribution. disruptive selection , diversifying selection selection favoring the two extremes rather than the intermediate. natural selection the survival in nature of those individuals and their progeny best equipped to adapt to environmental conditions. sexual selection natural selection in which certain characteristics attract male or female members of a species, thus ensuring survival of those characteristics. stabilizing selection selection favoring intermediate phenotypes rather than those at one or both extremes.
natural selection, the natural evolutionary processes by which the organisms that are best adapted to an environment tend to survive and propagate whereas those that are unfit are less likely to do so. Compare artificial selection. natural occurs in nature, without the intervention of humans. natural experiments occur by chance when all variables for a population are constant except one, which is different for one large part of the population compared with the other, e.g. when half of a flock comes from one climate and the other half is a local resident in another climate. natural focus the ecology that is best suited to a biological system, e.g. an individual insect-borne disease; the area in which the disease naturally flourishes best; an ecological niche. natural history history of a process or organism as it occurs in nature, e.g. course of a disease from infection to resolution. natural killer (NK) cell see natural killer cell. natural selection selection occurring in nature, without any human intervention, direct or indirect. natural ventilation ventilation without the use of artificially induced energy and the machines which it drives; the forces used are wind and the exchange of heat from within the barn and the external air, controlled by ventilation devices in the walls and the ceiling. 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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