Two genes control fur color in Labrador retrievers.The first gene determines whether the pigment to be deposited in the hair will be black or brown.The second gene determines whether the pigments are put into the dog's hair at all.A dog homozygous for the recessive allele of this second gene will be yellow because no pigment is deposited in its fur.This is an example of
A) epistasis.
B) pleiotrophy.
C) codominance.
D) incomplete dominance.

Question

Quizplus · Accepted Answer

Epistasis occurs when one gene affects the expression of another gene. In this case, the second gene (responsible for pigment deposition) affects the expression of the first gene (responsible for black or brown color). If the second gene is homozygous recessive, it prevents any pigment from being deposited regardless of the first gene's expression. This results in a yellow coat color, regardless of whether the first gene would have produced a black or brown coat color.

Two Genes Control Fur Color in Labrador Retrievers