Module 8

1. Module 8

1.16. Page 5

Lesson 3

Module 8—Populations, Individuals, and Gene Pools

Lesson Summary

This lesson focused on the following questions:

How can the Hardy-Weinberg equation, involving allele and genotype frequencies in populations, graphs, and population data, be used to study changes in population over time?
How do we analyze and interpret this data to make predictions and decisions about population management?

The Hardy-Weinberg equation is a tool that is used to determine if genetic change (microevolution) is actually occurring in a population.

p represents the frequency (number/total) of the dominant allele in the gene pool.
q represents the frequency of the recessive allele in the gene pool.
p + q = 1 because the dominant alleles plus the recessive alleles make up the whole gene pool.
p2 represents the frequency of the homozygous dominant genotype in the population = f(AA).
2pq represents the frequency of the heterozygous genotype = f(Aa).
q2 represents the frequency of the homozygous recessive genotype = f(aa).
p2 + 2pq + q2 = 1 because f(AA) + f(Aa) + f(aa) = all the individuals of the population.

Lesson Glossary

Consult the glossary in the textbook for other definitions that you may need to complete your work.

frequency: how common something is; usually expressed as a decimal percentage; e.g., an incidence of “2 in 5” gives the same information as a frequency of 0.4 or 40%

Hardy-Weinberg equation: an equation used to determine the frequency of genotypes: p2 + 2pq + q2 = 1, where p = frequency of the dominant allele and q = frequency of the recessive allele

If the frequency of genotypes is known, the equation can be used to work backwards to find the frequency of alleles in the gene pool.