Unlike normal epistasis, the F2 generation shows a phenotypic ratio of 9:3:4. The recessive epistasis involves the individuals with one single dominant allele or two pairs of recessive alleles ( example A/- b/b and a/a b/ b). Let us consider an example of recessive epistasis in rodents. The coat color in rodents is a classic example of recessive epistasis. The wild-type mice exhibit a grayish coat color since their fur consists of a combination of black and yellow banding of hairs. This type of coloration is also known as agouti pattern of coat color. The Albino mice have a white coat color and pink eyes since they do not produce the pigment. Other variants are completely black. Consider a cross between the agouti mouse (A/A G/G) and an albino mouse (a/a g/g). The F1 progeny are all agouti mice (A/a G/g). Interbreeding of the agouti progeny or the F1 generation gives rise to F2 progeny consisting of 9 agouti mice ( A/- G/-), 3 black mice (a/a G/-), and 4 albino mice (g/g) or (A/- g/g). Hence the phenotypic ratio is 9:3:4. Black mice have dominant alleles and the albino mice have recessive alleles. In this case, the dominant allele (G) leads to pigment formation. The recessive allele (g allele) stops the expression of the pigment when present In a double dose or homozygous state. Also, the dominant allele for the agouti (A) helps in the expression of agouti coat color. The recessive allele (a) gives rise to no agouti color. Another example of recessive epistasis involves the coat color in the Labrador retrievers. Black, brown, and yellowish white coat colors are present in these species.