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Time course imaging of two maize inbreds and their F1 hybrid (middle) exhibiting heterosis. Heterosis, hybrid vigor, or outbreeding enhancement is the improved or increased function of any biological quality in a hybrid offspring. An offspring is heterotic if its traits are enhanced as a result of mixing the genetic contributions of its parents
Inbreeding is also used to reveal deleterious recessive alleles, which can then be eliminated through assortative breeding or through culling. In plant breeding, inbred lines are used as stocks for the creation of hybrid lines to make use of the effects of heterosis. Inbreeding in plants also occurs naturally in the form of self-pollination.
Allogamy ordinarily involves cross-fertilization between unrelated individuals leading to the masking of deleterious recessive alleles in progeny. [11] [12] By contrast, close inbreeding, including self-fertilization in plants and automictic parthenogenesis in hymenoptera, tends to lead to the harmful expression of deleterious recessive alleles (inbreeding depression).
The divergence between the (two) parent lines promotes improved growth and yield characteristics in offspring through the phenomenon of heterosis ("hybrid vigour" or "combining ability"). Two populations of breeding stock with desired characteristics are subjected to inbreeding until the homozygosity of the population exceeds a certain level ...
Darwin's wife, Emma, was his first cousin, and he was concerned about the impact of inbreeding on his ten children, three of whom died at age ten or younger; three others had childless long-term marriages. [16] [17] [18] Humans do not seek to completely minimize inbreeding, but rather to maintain an optimal amount of inbreeding vs. outbreeding.
The results show that haplogroup D introgressed 37,000 years ago (based on the coalescence age of derived D alleles) into modern humans from an archaic human population that separated 1.1 million years ago (based on the separation time between D and non-D alleles), consistent with the period when Neanderthals and modern humans co-existed and ...
A human chimera is a human with a subset of cells with a distinct genotype than other cells, that is, having genetic chimerism.In contrast, an individual where each cell contains genetic material from a human and an animal is called a human–animal hybrid, while an organism that contains a mixture of human and non-human cells would be a human-animal chimera.
A decrease in these areas is known as inbreeding depression. A hybrid between two inbred strains can be used to cancel out deleterious recessive genes resulting in an increase in the mentioned areas. This is known as heterosis. [11]