Brifly describe the non additive gene action and thier major characteristics
Non-additive gene action refers to the interaction or expression of genes in a way that does not follow a simple additive pattern. In other words, the combined effect of two or more genes is not equal to the sum of their individual effects.
There are several major characteristics of non-additive gene action, including:
1. Epistasis: Epistasis occurs when the effect of a gene at one locus is dependent on the presence or absence of alleles at another locus. This can result in the masking or modification of the phenotypic expression of certain genes. Epistasis can be either dominant or recessive.
2. Pleiotropy: Pleiotropy refers to the phenomenon where a single gene can affect multiple seemingly unrelated traits or phenotypes. This means that the expression of a single gene can have multiple effects throughout an organism's development or physiology.
3. Gene interactions: Genes can interact with each other in various ways, such as synergism or redundancy. Synergism occurs when the combined effect of two or more genes is greater than the sum of their individual effects, while redundancy occurs when multiple genes have overlapping or redundant functions.
4. Dominance/recessiveness: Non-additive gene action can result in the dominance or recessiveness of certain genes. Dominant genes are expressed in the presence of either one or two copies of the dominant allele, while recessive genes are only expressed in the presence of two copies of the recessive allele.
5. Non-linear gene effects: Non-additive gene action often leads to non-linear gene effects, meaning that the phenotypic expression is not directly proportional to the number or presence of particular alleles. This can contribute to the creation of genetic variation and complexity in traits.
Overall, non-additive gene action adds a layer of complexity to the understanding of genetic inheritance and the expression of traits. It highlights the importance of gene interactions and the potential for unexpected phenotypic outcomes.