Question

Incomplete dominanceand epistasis are both terms that define genetic relationships. What is the most basic distinction between these terms?

Short answer

Incomplete dominance shows the relationship or coordinated effects of two different gene alleles. On the other hand, epitasis describes the relationship between two different genes.

Incomplete dominance is the partial expression of alleles of a gene by the effect of each other. Epistasis is the condition when the effect of one gene is decided by the presence of another gene or genes.

Step-by-step solution

Step 1: Incomplete dominance

Incomplete dominance contrasts the relationship described by John Gregor Mendel by the rule of dominance (when a dominant allele suppresses the effect of recessive allele completely).

In incomplete dominance, the dominant allele cannot completely mask the effect of recessive, and both alleles give mixed effects.

Epistasis

Epistasis is the phenomenon used in genetics that describes the relationship between different genes when the expression of one gene is affected by the presence of another one or more genes.

As described by Mendel, it is also a gene interaction that variates the genetic relationships. It states that all genes assort independently and give their individual effect.

Step 3: Distinction between incomplete dominance and epistasis

Incomplete dominance involves only different alleles of the same gene means it involves only one gene locus. For example, in Mirabilis jalapa, the dominant allele for the red color of the flower cannot mask the recessive allele of the white color, and offspring with pink colored flower is produced.

Epistasis is the interaction of two or more genes, so it involves two or more gene loci. One example of epistasis is polygenic inheritance in skin color when three genes decide the skin color in humans.