Remember that,in Labrador retrievers,B (black coat)is dominant to b (brown coat)and homozygosity for the recessive epistatic allele e always results in a yellow coat.A brown female is crossed to a yellow male,and their progeny consists of six black puppies.Interestingly,when one of the F₁ females is crossed to her yellow father,she gives birth to seven puppies: three yellow,three black,and one brown. What are the most likely genotypes of the original brown female and yellow male?

Question

Quizplus · Accepted Answer

The original brown female must be homozygous recessive for the B locus (b/b) and must possess at least one dominant E allele to express the brown color (E/E or E/e). Since the yellow male produces black offspring, he must carry the B allele but be homozygous recessive at the E locus (e/e) to express the yellow phenotype. The fact that their offspring include black, brown, and yellow puppies indicates that the male must also carry the b allele (making him B/b;e/e) to produce brown offspring when crossed with the b/b;E/E female.

Remember That,in Labrador Retrievers,B (Black Coat)is Dominant to B (Brown