Question

Hardy-Weinberg problem:

A local kennel currently has 100 border collies. There are 70 dogs with blue eyes, the recessive trait, living there. What percentage of the population is homozygous dominant, homozygous recessive, and heterozygous?

Answer 1

Remember the basic formulas:

p2 + 2pq + q2 = 1 and p + q = 1

p = frequency of the dominant allele in the population
q = frequency of the recessive allele in the population
p2 = percentage of homozygous dominant individuals
q2 = percentage of homozygous recessive individuals
2pq = percentage of heterozygous individuals

Now here the frequency of recessive allele I.e q is 70/100 = 0.7

Thus p or the frequency iof dominant allele would be p + q = 1

0.7 + p = 1

P = 1- 0.7 = 0.3

Thus the percentage of homozygous dominant individual is p2 = 0.3 x 0.3 = 0.09 =9%

Percentage of homozygous recessive individuals = q2 = 0.7 x 0.7 = 0.49 or 49%.

Percentage of heterozygous individuals = 2Pq = 2 x 0.7 x 0.3 = 0.42 or 42%.