In the yawncat (a rare hypothetical animal), the dominant allele R causes solid tail color, and the recessive allele r results in white spots on a colored background.The black coat color allele B is dominant to the brown allele b, but these genes can only be expressed if the animal has an mm genotype at a third gene locus.Animals that are M_ are yellow regardless of which allele from the B locus is present.A mating between a solid yellow-tailed male yawncat and a solid brown-tailed female yawncat produces 16 offspring with the following tail phenotypes: six solid yellow, two spotted yellow, three solid black, one spotted black, three solid brown, and one spotted brown.What is the MOST likely genotype of the male parent?

Question

Quizplus · Accepted Answer

From the offspring, we can deduce the following: 
- Solid yellow tail phenotype indicates that the animal is at least M_. Therefore, all six solid yellow offspring are M_.
- Two of the offspring have the spotted yellow phenotype, indicating that they must be mm at the third gene locus. This means that their tail color is determined solely by the presence of the R or r allele at the second gene locus. Since they have the spotted phenotype, we know that their genotype is Rr.
- Three of the offspring have the solid black phenotype, indicating that they are BB at the first gene locus. Since they are also M_, they must be BBMM.
- One of the offspring has the spotted black phenotype, indicating that it must be Bb at the first gene locus and mm at the third gene locus. This means its tail color is determined solely by the presence of the R or r allele at the second gene locus. Since it has the spotted phenotype, we know that its genotype is Rr.
- Three of the offspring have the solid brown phenotype, indicating that they are bb at the first gene locus. Since they are also M_, they must be bbMM.
- One of the offspring has the spotted brown phenotype, indicating that it must be bb at the first gene locus and mm at the third gene locus. This means its tail color is determined solely by the presence of the R or r allele at the second gene locus. Since it has the spotted phenotype, we know that its genotype is Rr.

Using this information, we can deduce the genotypes of the parents. The female must be bbRR since all of her offspring have at least one b allele at the first locus and at least one R allele at the second locus. The male must be MmBbRr since he is the only parent that can produce all of the observed phenotypes in his offspring.

In the Yawncat (A Rare Hypothetical Animal), the Dominant Allele