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.