A researcher is studying the inheritance of scale color in a

A researcher is studying the inheritance of scale color in a new species of guppy. Base your answer on ALL of the following information. When she crossed homozygous brown males with homozygous blue females, the F1 progeny consisted of 47 blue males and 43 brown females. When these fish were intercrossed, the F2 progeny consisted of 33 blue males, 12 brown males, 10 blue females, and 37 brown females.
When she performed the reciprocal cross, the F1 progeny consisted of 37 blue males and 39 brown females. When these individuals were intercrossed, the F2 progeny consisted of 63 blue males, 19 brown males, 22 blue females, and 59 brown females. What type of trait is this?

Solution

The trait seems to be sex dependent.

Females fish express brown color or prefer brown color. This can be determined as in F1 generation, all females are brown despite the presence of a copy of blue allele. In F2 generation, most females are brown and only a few female fish, with both alleles coding for blue, show a phenotype for blue scales. Therefore, it can be said brown is dominant in females and blue is recessive in females.

Similarily, Males prefer blue. This can be determined as in F1 generation, all males are blue despite the presence of a copy of brown allele. In F2 generation, most males are blue and only a few male fish, with both alleles coding for brown, show a phenotype for brown scales. Therefore, it can be said blue is dominant in males and brown is recessive in males.