Hardy-Weinberg Equilibrium Calculator
Calculate allele and genotype frequencies using Hardy-Weinberg equilibrium principles. Determine if populations are evolving with population genetics calculations
Value between 0 and 1 (e.g., 0.6 for 60%)
Value between 0 and 1 (will be auto-calculated if p is entered)
The observed frequency of individuals showing the recessive trait (aa genotype)
Allele Frequencies
p (dominant allele):
q (recessive allele):
Verification:
Expected Genotype Frequencies
p² (AA - Homozygous Dominant):
2pq (Aa - Heterozygous):
q² (aa - Homozygous Recessive):
Verification:
Genotype Distribution
Equilibrium Assessment
Understanding Hardy-Weinberg Equilibrium
The Hardy-Weinberg equilibrium principle states that allele and genotype frequencies in a population will remain constant from generation to generation in the absence of evolutionary influences. This mathematical model serves as a null hypothesis for studying evolution, allowing scientists to detect when populations are evolving.
The Hardy-Weinberg Equations
Allele Frequency: p + q = 1
Genotype Frequency: p² + 2pq + q² = 1
- • p = frequency of the dominant allele
- • q = frequency of the recessive allele
- • p² = frequency of homozygous dominant genotype (AA)
- • 2pq = frequency of heterozygous genotype (Aa)
- • q² = frequency of homozygous recessive genotype (aa)
Five Conditions for Hardy-Weinberg Equilibrium
- No mutations: No new alleles are introduced to the gene pool through mutation
- Random mating: All individuals have an equal opportunity to reproduce
- No gene flow: No migration of individuals into or out of the population
- Large population size: The population is large enough to prevent genetic drift
- No natural selection: All genotypes have equal fitness and survival rates
Applications in Population Genetics
Detecting Evolution
By comparing observed genotype frequencies to Hardy-Weinberg predictions, scientists can determine if a population is evolving and identify which evolutionary mechanisms are at work.
Estimating Carrier Frequency
For recessive genetic disorders, the Hardy-Weinberg equation can estimate the frequency of heterozygous carriers in a population, which is crucial for genetic counseling and public health planning.
Conservation Biology
Used to assess genetic diversity in endangered species and evaluate the effectiveness of conservation strategies aimed at maintaining genetic variation.
Medical Genetics
Helps predict the prevalence of genetic diseases in populations and understand the distribution of disease alleles across different ethnic groups.
Example Calculation
Problem: Calculating Carrier Frequency for Cystic Fibrosis
Cystic fibrosis is a recessive genetic disorder. In a certain population, 1 in 2,500 individuals are born with cystic fibrosis (genotype aa).
Step 1: Calculate q² (frequency of aa genotype)
q² = 1/2,500 = 0.0004
Step 2: Calculate q (frequency of recessive allele)
q = √0.0004 = 0.02 (2%)
Step 3: Calculate p (frequency of dominant allele)
p = 1 - q = 1 - 0.02 = 0.98 (98%)
Step 4: Calculate 2pq (frequency of carriers)
2pq = 2 × 0.98 × 0.02 = 0.0392 (3.92%)
Result: Approximately 4% of the population are carriers of the cystic fibrosis allele.
References
The Hardy-Weinberg principle and its applications are based on established population genetics research:
Related Calculators
Note: This calculator provides theoretical predictions based on the Hardy-Weinberg equilibrium model. Real populations rarely meet all five conditions perfectly, so some deviation from predicted values is expected. Significant deviations may indicate evolutionary forces acting on the population.
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