Information AboutHeterosis |
| CATEGORIES ABOUT HETEROSIS | |
| classical genetics | |
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Heterosis is a term used in Genetics and Selective Breeding . The term heterosis, also known as '''hybrid vigor''', '''hybrid vigour''', or '''outbreeding enhancement''', describes the increased strength of different characteristics in Hybrid s; the possibility to obtain a "better" individual by combining the virtues of its parents. ]] Heterosis is often the opposite process of Inbreeding Depression , which increases Homozygosity . Although it is believed that heterosis is the action of many genes of small effect, whereas inbreeding depression is the action of a few genes of large effect. The term often causes controversy, particularly in terms of the selective breeding of Domestic Animal s, because it is sometimes believed that all Crossbred plants or animals are better than their parents; this is not necessarily true. Rather, when a hybrid is seen to be superior to its parents, this is known as hybrid vigor. It may also happen that a hybrid inherits such different traits from their parents that make them unfit for survival. This is known as Outbreeding Depression , typical examples of which are crosses between wild and hatchery fish that have incompatible adaptations. Heterosis can be classified into mid-parent heterosis, in which the hybrid shows increased strength which is greater than the average of both parents, and '''best-parent heterosis''', in which the hybrid's increased strength is greater than that of the strongest parent. Mid-parent heterosis is more common in nature, and it is easier to explain (by mechanism of gene dominance; see below). GENETIC BASIS OF HETEROSIS |
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