Question

A rooster with gray feathers is mated with a hen of the same phenotype. Among their offspring, 15 chicks are gray, 6 are black, and 8 are white. What is the simplest explanation for the inheritance of the colors in chickens? What phenotypes would you expect in the offspring of a cross between a gray rooster and a black hen?

Answer 1

The simplest explanation for the inheritance of feather colors in chickens, with gray, black, and white offspring, is incomplete dominance. A gray rooster crossed with a black hen would likely produce about half gray and half black offspring, indicating the heterozygous nature of the gray phenotype.

Step-by-step explanation:

When discussing the inheritance of feather color in chickens, such as gray, black, and white, this scenario appears to illustrate a case of incomplete dominance. Incomplete dominance is when the phenotype of the heterozygotes is intermediate between the phenotypes of the two homozygotes. Based on the offspring of the gray rooster and gray hen, where we have gray, black, and white chicks, it is likely that gray is the result of incomplete dominance between black and white alleles. If a gray rooster (presumably heterozygous with one black and one white allele) was crossed with a black hen (homozygous for black alleles), we would expect roughly half the offspring to be gray and the other half to be black.

If we consider a similar example where all chickens from black and white parents are speckled, this is an indication of incomplete dominance as well. When the speckled chickens are interbred, we would expect a phenotypic ratio, as suggested by the provided information, where 50% of the offspring will be speckled, 25% will be black, and 25% will be white.