The HERC2 gene is one among several determinant of eye color

The HERC2 gene is one (among several) determinant of eye color variation in humans. There are two common alleles A and G, with GG homozygotes usually having blue eyes and AA homozygotes or AG heterozygotes usually having brown eyes. Suppose a human population contained 91% of brown-eyed individuals and 9% with blue eyes and that this variation was entirely due to the HERC2 locus. Under the Hardy-Weinberg assumptions, what is the frequency of the A allele in the population?

Solution

Answer: The frequency of the A allele in the population= 0.7

Explanation:

The frequency of blue eye (GG, Recessive) = q² = 9/100 = 0.09

The frequency of recessive allele (G) = q = 0.3

The frequency of brown allele (A, dominant) = 1-q = 1-0.3 = 0.7

AA = 0.49

GG = 0.09

AG = 2 * 0.7 * 0.3 = 0.42