Incomplete Penetrence, Variable Expressivity, and Epistasis

In a type of parakeet known as a “budgie”, feather color is controlled by two genes.

A yellow pigment is synthesized under control of a dominant allele Y.

Recessive homozygotes with the yy genotype homozygous do not synthesize yellow pigment. ---------yy

the dominant allele B directs synthesis of a blue pigment.

Recessive homozygotes with the bb genotype do not produce blue pigment.----------bb

Budgies that produce both yellow and blue pigments have green feathers; those that produce only the yellow pigment or only the blue pigment have yellow or blue feathers, respectively; and

budgies that produce neither pigment are white (albino).

A cross of a green budgie and a yellow budgie produces offspring that are 12 green, 4 blue, 13 yellow, and 3 albino. What are the genotypes of the parents?

Y_B_ =green;

yyB_ = blue;

Y_bb = yellow

and yybb = white

YyBb and yyBb --------------genotypes of the parents