4. Plumage in ducks is determined by a multiple allelic series of alleles named

Question

4. Plumage in ducks is determined by a multiple allelic series of alleles named restricted (MR = white on the wing fronts), mallard (M = wild type), and dusky (md = darker plumage). MR is dominant to M, which is dominant to md.

a. Can a mating between two mallard ducks produce offspring with restricted plumage? Explain your answer.

b. A series of matings between two mallard ducks produced the following offspring: 21 mallard and 7 dusky. What are the likely genotypes of the two mallard parents? Explain or diagram your answer.

c. Can a mating between two ducks with restricted plumage produce offspring with dusky plumage? Explain using diagrams of appropriate matings.

Explanation / Answer

The six genotypes possible with these three alleles and their result­ing phenotypes are:

Genotype

Phenotype

MRMR

restricted

MRM

restricted

MRmd

restricted

MM

mallard

Mmd

mallard

mdmd

dusky

a. No, because no mallard duck has allele R in its genotype. So, there is no possible combination that contains R allele.

b.

Cross the mallard ducks:

Cross 1 with parents MM X MM

Cross 2 with parents Mmd X Mmd

This genotype gives nearly 21:7 mallard to dusky phenotypes. So, the most likely genotype of the two mallard parents is Mmd.

Genotype

Phenotype

MRMR

restricted

MRM

restricted

MRmd

restricted

MM

mallard

Mmd

mallard

mdmd

dusky

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