1. Calculate allele frequency and genotype frequency for a
herd of horses in which p = 0.32.
p = .32, q = .68
HH = (.32)(.32) = .1024
Hh = 2(.32)(.68) = .4352
hh = (.68)(.68) = .4624
2. In a small village in Africa, 15% of the population is born
with sickle-cell anemia (aa). (q2 = .15)
1. What is the frequency for the “A” allele?
p = 1 - .3873 = .6127
2. What is the frequency for the “a” allele?
q = .3873
3. What are the three genotype frequencies?
AA = p2 = (.6127)2 = .3754
Aa = 2pq = 2(.6127)(.3873) = .4746
aa = .15
4. Assuming Hardy-Weinberg equilibrium, how many
individuals in a neighboring village of 3,500 would be
expected to be heterozygous?
3,500(.4746) = 1661.1 = 1661 individuals
A butterfly population has two colors: brown wings and white
wings. Brown wings are dominant. The frequency of the
brown allele is .8. Find everything else (allele frequencies and
genotype frequencies).
p = .8 = 80% brown wing allele
q = .2 = 20% white wing allele
BB = p2 =.8(.8) = .64 = 64% BB
Bb = 2pq = 2(.8)(.2) = .32 = 32% Bb
bb = q2 = .2(.2) = .04 = 4% bb
Recall: p + q = 1 (allele frequencies)
p2 + 2pq + q2 (genotype frequencies)