A roan horse is one that has patches of white and patches of reddish brown hair because the genes for the two hair colors are equally expressed what is this an example of

Codominance

Explanation:

Codominance is the pattern of inheritance in which the heterozygote equally expresses the phenotypes of both types of homozygotes.

According to the given information, hair color in horses is regulated by two alleles. One allele gives red-brown hairs while the other allele gives white hairs. However, none of the alleles is completely dominant over the other. Heterozygous horses have a mixture of reddish-brown hairs and white hairs, which is called roan. Because the alleles for reddish-brown and white-colored hairs are expressed equally in the roan heterozygote, this represents an example of codominance.