What is Hardy-Weinberg Equilibrium?
The Hardy-Weinberg principle states that allele and genotype frequencies remain constant in a population from generation to generation in the absence of evolutionary influences. This model helps geneticists understand population genetics and detect when evolution is occurring.
p² + 2pq + q² = 1
Formula for two alleles (p and q)
How to Use This Calculator
- Select the number of alleles (2-5)
- Enter the frequency for each allele
- Ensure frequencies sum to 1.0
- Click "Calculate" to see genotype frequencies
- View the complete breakdown of all possible genotypes
Assumptions of Hardy-Weinberg
The Hardy-Weinberg equilibrium requires five conditions:
- No mutations: Allele frequencies don't change due to mutations
- Random mating: All individuals have equal opportunity to mate
- No gene flow: No migration in or out of the population
- Large population: No genetic drift from small population size
- No selection: All genotypes have equal fitness
Number of Genotypes
The number of possible genotypes can be calculated using the formula:
Genotypes = n(n + 1) / 2
Examples:
- 2 alleles: 3 genotypes (AA, Aa, aa)
- 3 alleles: 6 genotypes
- 4 alleles: 10 genotypes
- 5 alleles: 15 genotypes
Example Calculation
For a two-allele system with frequencies:
p = 0.6 (allele A)
q = 0.4 (allele a)Genotype frequencies will be:
- AA: p² = 0.36 (36%)
- Aa: 2pq = 0.48 (48%)
- aa: q² = 0.16 (16%)
Applications
Hardy-Weinberg equilibrium is used to:
- Detect evolutionary changes in populations
- Calculate carrier frequencies for genetic diseases
- Study conservation genetics
- Predict genotype distributions
- Analyze population structure