Here is a problem to illustrate how the Hardy-Weinberg Principle is applied.
In a population of 130,000 special mice, green fur is dominant over orange. If there are 300 orange mice in the population of 130,000, find the following:
Frequency of green allele
Frequency of orange allele
Frequency of each genotype
p + q = 1
p2 + 2 pq + q2 = 1
We must start with orange as it is the recessive one. It is because, from the dominant (green) colour, it is impossible to say that it is homozygous dominant or heterozygous. Whereas only homozygous recessive has orange fur.
q2 = 300/130,000 = 0.0023
q = sqrt(q2) = 0.048
p = 1 – q = 0.95
Genotype Frequencies:
homozygous dominant = p2 = 0.90
Heterozygous = 2pq = 0.0456 = 0.091
Homozygous recessive = q2 = 0.0023
Reference
The Hardy-Weinberg Principle: Watch your Ps and Qs: ThePenguinProf
