4. Plumage in ducks is determined by a multiple allelic series of alleles named
ID: 53294 • Letter: 4
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