Question

4. In Drosophila melanogaster, the phenotype curly wings is due to a mutant allele Cy that is lethal when homozygous. A population is established with an initial frequency of Cy equal to 0.168. Denoting + as the wild- type (i.e. non-mutant) allele at this locus, calculate the expected frequency of Cy in the next generation if the relative fitness of the ++ homozygote to the Cy/+ heterozygote is:
a) 1 : 1
b) 1 : 0.5
c) Briefly explain why the change in frequency of the Cy allele is greater in one case than the other.

Answer 1

C. Frequency of Cy allele is found to be greater in the part b where the relative fitness of heterozygotes i.e. W_cy/+ is given as 0.5. This is a clear example of heterozygote advantage which is described as the selection of individuals with heterozygote genotype over other genotypes as heterozygosity increases the chances of survival of a living being. So, those individuals who have heterozygote genotype, are more genetically fit than others.