We're going to look at a much simpler case in this lecture. We're going to discuss how dogs basically pass down their coat color. So another relatively simple example of epistasis is the inheritance of coat colors in certain types of dogs. So in certain dogs, we have two different allele pairs at two different low side that ultimately determine the expression of some particular color trait, the code color trait. So to designate these different types of allele pairs, we're going to use the letter D to designate one allele pair and the letter B to designate the second allele pair. So let's begin by supposing that we have a dog that is homozygous dominant.