Question

In zebras, gene B is responsible for producing black pigment resulting in the traditional black striped pattern. The wildtype dominant allele of gene B produces black pigment, and black stripes, and a null allele (b) results in brown pigment and brown stripes in the homozygous condition. Gene S produces an enzyme that deposits the pigment. The wildtype dominant allele of gene S produces striped animals and a null allele (s) results in animals with no stripes (all white) in the homozygous condition. Two zebras, who are both dihybrid for gene B and gene S mate.

Is gene B is epistatic to Gene s or is it the other way around?

Answer 1

Gene S is epistatic to Gene B i.e. if gene S is homozygous recessive, then gene B won't be expressed at all.

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