Heterosis is a term used in genetics and selective breeding. The term heterosis, also known as hybrid vigor or out breeding enhancement, describes the increased strength of different characteristics in hybrids; the possibility to obtain a "better" individual by combining the virtues of its parents.
Heterosis is the opposite of inbreeding depression, which occurs with increasing homozygosity. The term often causes controversy, particularly in terms of the selective breeding of domestic animals, 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 this makes them unfit for survival. This is known, as out breeding depression, typical examples of which are crosses between wild and hatchery fish that have incompatible adaptations.
Heterosis, or hybrid vigor, refers to the phenomenon that progeny of diverse inbred varieties exhibit greater biomass, speed of development, and fertility than the better of the two parents. This phenomenon has been exploited extensively in crop production and has been a powerful force in the evolution of plants. The genetic basis has been discussed for nearly a century, but little consensus has emerged. With the advent of the genomic era, the tools to establish a molecular basis for heterosis are at hand. In the past, there has been a tendency to attribute any molecular differences between the parents and progeny as contributing to the basis of heterosis. Some individuals dismiss the phenomenon as hopelessly complex. It seems likely, however, that the complexity derives from its multigenic nature and that eventually a unifying principle will emerge.
Heterosis is the opposite of inbreeding depression, which occurs with increasing homozygosity. The term often causes controversy, particularly in terms of the selective breeding of domestic animals, 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 this makes them unfit for survival. This is known, as out breeding depression, typical examples of which are crosses between wild and hatchery fish that have incompatible adaptations.
Heterosis, or hybrid vigor, refers to the phenomenon that progeny of diverse inbred varieties exhibit greater biomass, speed of development, and fertility than the better of the two parents. This phenomenon has been exploited extensively in crop production and has been a powerful force in the evolution of plants. The genetic basis has been discussed for nearly a century, but little consensus has emerged. With the advent of the genomic era, the tools to establish a molecular basis for heterosis are at hand. In the past, there has been a tendency to attribute any molecular differences between the parents and progeny as contributing to the basis of heterosis. Some individuals dismiss the phenomenon as hopelessly complex. It seems likely, however, that the complexity derives from its multigenic nature and that eventually a unifying principle will emerge.
