Hardy-Weinberg Equilibrium

• Hardy-Weinberg Equilibrium


  A population's allele and genotype frequencies are constant, unless there is some type of evolutionary force acting upon them
• Assumptions of Hardy-Weinberg Equilibrium

  • No Selection
  • No Mutation
  • No Migration
  • Large population
  • Random Mating
• Allele frequency


  Describes how often an allele appears in a population
• Genotype frequency


  How often we see each allele combo
• Phenotype frequency


  How often we see a physical trait
• Hardy-Weinberg Equilibrium was developed by Godfrey Hardy and Wilhelm Weinberg (Mathematician and Physician)
• The assumptions of Hardy-Weinberg Equilibrium are impossible to achieve in real life
• The Hardy-Weinberg Equilibrium is a useful principle for thinking through what percentage might be of a certain allele or genotype in a population
• p


  Dominant allele
• q


  Recessive allele
• Genotype Frequencies


  • p^2 (Homozygous dominant)
  • 2pq (Heterozygote)
  • q^2 (Homozygous recessive)
• Solving Hardy-Weinberg Equilibrium Problems

  1. Determine which equation to work with first

  2. Figure out what missing value you can determine

  3. Use the known values to solve the problem
• Frog color


  • Dark Green (GG or Gg)
  • Light Green (gg)
• In the frog color example, the allele frequencies are p=0.5 and q=0.5
• In the frog color example, the genotype frequencies are p^2=0.25 (25%), 2pq=0.5 (50%), and q^2=0.25 (25%)
• Given: 500 total number of frogs, 375 dark green frogs. The allele frequencies are p=0.5 and q=0.5, and the genotype frequencies are p^2=0.25 (25%), 2pq=0.5 (50%), and q^2=0.25 (25%)