What is the Difference Between Additive and Non Additive Gene Action?

The difference between additive and non-additive gene action lies in the way multiple genes or alleles interact and contribute to a specific phenotype or trait.

Additive gene action occurs when the effects of multiple genes or alleles are combined in a linear or additive manner. In this case, each allele contributes equally to the expression of the trait, and the resultant phenotype is a combination of the effects of the individual alleles. Additive gene action is shown under heterozygous conditions and is characterized by the following features:

The substitution of one allele for another produces the same plus or minus effect regardless of whether the replacement occurs in a homozygote or heterozygote condition.
When different allelic combinations are substituted for each other, the resulting mean remains constant.

Non-additive gene action refers to the interactive effects of different alleles, including genetic dominance (within locus interaction) and epistasis (across locus interaction). In non-additive gene action:

One allele may mask the expression of another allele due to the dominant-recessive relationship, resulting in a different phenotypic outcome.
The interaction between alleles at different gene loci can give rise to different gene actions, which are not purely additive.

In summary, additive gene action involves the linear or additive contribution of multiple genes or alleles to a specific phenotype, while non-additive gene action involves interactive effects of different alleles and includes genetic dominance and epistasis.

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What is the Difference Between Additive and Non Additive Gene Action?

Comparative Table: Additive vs Non Additive Gene Action

Additive and non-additive gene actions refer to the different ways alleles interact and contribute to the phenotype. Here is a table summarizing the main differences between additive and non-additive gene action:

Feature	Additive Gene Action	Non-Additive Gene Action
Definition	Both alleles contribute equally to the phenotype, and their effects are measurable and additive.	Only one allele contributes to the phenotype through dominance or epistasis, and the effect is not additive.
Contribution to Phenotype	The resultant phenotype is a combination of the two homozygous (homozygous dominant and homozygous recessive) contributions.	The dominant allele masks the expression of the recessive allele, resulting in the organism displaying the dominant trait.
Allelic Interaction	Both alleles have an equal opportunity to be expressed, giving rise to the phenotype.	There is an interaction between genes or alleles, leading to genetic dominance or epistasis.
Influence on Traits	Additive gene action contributes to the variation in populations.	Non-additive gene action contributes to variation in populations through dominance or epistasis.

In summary, additive gene action involves both alleles contributing equally to the phenotype, while non-additive gene action involves one allele dominating the other, leading to a different phenotypic expression.

Guilherme Mazui

Guilherme Mazui is graduated in journalism from the Federal University of Minas Gerais (UFMG) and a master's degree in Communication from the University of São Paulo (USP). In addition, he has experience in advertising writing and has worked as a content editor in several companies.