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 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.

selection The process that determines the relative share of different genotypes which individuals possess and propagate in a population. The relative probability of survival and reproduction of a genotype is termed the adaptive value. Selection may be natural (i.e. by nature) or artificial (i.e. by human action, e.g. plant or animal breeders).

selection The process by which one or more factors acting on a population produce differential mortality and favour the transmission of specific characteristics to subsequent generations. See artificial selection; directional selection; disruptive selection; natural selection; sexual selection; stabilizing selection.