Index >> Phenotypic Ratio >> Heterodominance

Heterodominance
When the heterozygotes have a more extreme phenotype than either of the corresponding homozygotes (homozygous parents), then it is usually referred to as overdominance, superdominance or heterodominance (Serra, 1959). For example, there is heterodominance, when the heterozygote Aa between a pair of factors which control size is bigger than the homozygotes  AA or aa. This type of allelic relation which implies interaction between the alleles, or of these with other factors of the genotype, may be found in qualitative characters and especially those such as size, production, vigour, etc., which are of importance in the breeding of animals and plants (For details see chapters 33 of inbreeding, outbreeding and hybrid vigour and chapter 34 of Quantitative genetics).