Question

You are studying a population of cichlid fish and a gene associated with scale shape, in which large scales allele is delineated as A1 and the small scales allele is delineated as A2. If this population is in Hardy-Weinberg equilibrium and the proportion of the A1 allele is 0.7, what is the expected proportion of the homozygous A2A2 genotype?

Answer 1

Hardy-Weinberg equilibrium:

· Hardy-Weinberg equation describes: The most possible distribution of the population genotype of the population, if the frequencies of the alleles are known.

· If allele frequencies are p and q, then the genotype frequencies are p2, q2, 2pq.

· A population is considered to be in Hardy-Weinberg equilibrium when: In a randomly mating population, allele frequency and genotype frequency remain constant.

· Thus, under Hardy-Weinberg equilibrium:

p+ q=1 and

p2+2pq + q2 = 1.

Given:

· Allele frequency for A1 = 0.7 = p

· As per Hardy-Weinberg equilibrium p+q = 1

· Thus, q = 1- 0.7 = 0.3 = Allele frequency of A2

· Genotype frequency for A2A2 = q2= (0.3)2=, 0.09