Haely Flores 11/16/23
Assignment 9
Hardy Weinberg
At Hardy-Weinberg equilibrium, allele frequencies do not change from one generation to the
next. Hardy-Weinberg equilibrium occurs only if a population meets all of the following
assumptions:
•natural selection does not occur
•no mutations
•the population is large enough to eliminate random changes in allele frequencies
•individual mate at random
•no migration
Assuming the assumptions of Hardy-Weinberg equilibrium are met, two equations represent
the relationship between allele frequencies and genotype frequencies.
•
p+q=1
•
p2+2pq+q2=1
p is the frequency of the dominant allele and q is the frequency of the recessive allele.
2pq fraction of heterozygous individuals
Let us take for example
In a class of 19 students, 12 can roll their tongue, and 7 can’t.
Possible individual genotypes are:
1. RR - can roll (Homozygous dominant)
2. Rr – can also roll (heterozygous dominant individual)
3. Rr – can’t roll (Homozygous recessive)
For both RR and Rr the fraction of the class that can roll is 12/19 = 0.63158
But we don’t what fraction is just RR or just Rr.
For rr, the fraction of the class that can’t roll is 7/19 = 0.36842
Here we are sure of the fraction of the class that is rr.
So, r x r = r2 = 0.36842
r = square root of 0.36842 = 0.60697
Remember p + q = 1
R + r = 1
