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Selective breeding (also called artificial selection) is the process by which humans use animal breeding and plant breeding to selectively develop particular phenotypic traits (characteristics) by choosing which typically animal or plant males and females will sexually reproduce and have offspring together.
The mode of reproduction of a crop determines its genetic composition, which, in turn, is the deciding factor to develop suitable breeding and selection methods. Knowledge of mode of reproduction is also essential for its artificial manipulation to breed improved types.
Prior to Robert Tryon’s study of selective rat breeding, concluded in 1942, many psychologists believed that environmental, rather than genetic, differences produced individual behavioral variations. Tryon sought to demonstrate that genetic traits often did, in fact, contribute to behavior.
Domestication has been defined as "a sustained multi-generational, mutualistic relationship in which one organism assumes a significant degree of influence over the reproduction and care of another organism in order to secure a more predictable supply of a resource of interest, and through which the partner organism gains advantage over individuals that remain outside this relationship ...
The existence of limits in artificial selection experiments was discussed in the scientific literature in the 1940s or earlier. [1] The most obvious possible cause of reaching a limit (or plateau) when a population is under continued directional selection is that all of the additive-genetic variation (see additive genetic effects) related to that trait gets "used up" or fixed. [2]
Selective breeding has been responsible for large increases in productivity. For example, in 2007, a typical broiler chicken at eight weeks old was 4.8 times as heavy as a bird of similar age in 1957, [ 36 ] while in the thirty years to 2007, the average milk yield of a dairy cow in the United States nearly doubled.
Zebras of the project in the animal camp on the slopes of Devil’s Peak, above Groote Schuur Hospital, Cape Town, South Africa. The Quagga Project is an attempt by a group in South Africa to use selective breeding to achieve a breeding lineage of Burchell's zebra (Equus quagga burchellii) which visually resemble the extinct quagga (Equus quagga quagga).
Bakewell established the principles of selective breeding—especially line breeding—in his work with sheep, horses and cattle; his work later influenced Gregor Mendel and Charles Darwin. [ 8 ] : 56 His most important contribution to sheep was the development of the Leicester Longwool, a quick-maturing breed of blocky conformation that formed ...