Understand the relationship
The reasoning behind the result
Starting genotype proportions must be declared
HWE mode: fAA=p², fAa=2p(1−p), faa=(1−p)²
HWE mode constructs model zygote proportions from one entered allele frequency. Entered-frequency mode retains the three supplied proportions exactly.
The calculator does not test whether equilibrium is appropriate or replace an observed departure.
Mean fitness is the normalization denominator
W̄ = Σ fgwg
Multiplying each starting genotype share by its entered component gives an unnormalized contribution after selection. Dividing by their sum makes the selected genotype shares sum to one.
If every weighted contribution is zero, the selected distribution is undefined and the calculation is rejected.
Allele frequency is counted from selected genotypes
p′ = f′AA + f′Aa/2
Each AA individual contributes two A copies and each heterozygote one of two. The displayed allele change is p′−p for this one deterministic step.
Dominance enters only through the independently entered heterozygote component.
A deterministic step omits other evolutionary forces
Drift, mutation, migration, assortative mating, linkage and changing fitness are absent. Repeating the output as a forecast would add assumptions not supplied here.
The model gives no uncertainty interval or evidence that observed frequency change was caused by selection.
Follow the numbers
Apply a recessive viability cost
- With p(A)=0.6, q(a)=0.4 and HWE starting proportions are 0.36 AA, 0.48 Aa and 0.16 aa.
- Weighting by 1, 1 and 0.5 gives contributions 0.36, 0.48 and 0.08.
- Mean fitness is W̄ = 0.92.
- Selected genotype shares are 0.391304, 0.521739 and 0.086957.
- The selected A frequency is 0.391304 + 0.521739/2 = 0.652174.
A rises by about 0.052174 in this declared one-generation deterministic viability model.
Quick guide
How to use this calculator
- Choose whether genotype proportions are an HWE model from p or explicit entered frequencies.
- Enter one comparable nonnegative fitness component for each genotype.
- Inspect both genotype shares and allele counts after the single weighting step; no later generation is projected.
Calculation method
Calculation and interpretation
Expose pre-selection genotype assumptions, mean fitness, post-selection genotype shares and allele counting without turning one generation into a long-term forecast.
W̄ = fAAwAA + fAawAa + faawaa; f′g = fgwg/W̄; p′(A) = f′AA + ½f′Aa
Worked example
Apply a recessive viability cost
A rises by about 0.052174 in this declared one-generation deterministic viability model.
W̄ = fAAwAA + fAawAa + faawaa; f′g = fgwg/W̄; p′(A) = f′AA + ½f′Aa
Supported inputs
Precision and limits
One diploid biallelic locus
The workbench uses AA, Aa and aa classes only and does not support sex linkage, multiple alleles or haplotypes.
One deterministic weighting step
No drift, mutation, migration, mating, linkage or later generation is simulated.
Entered fitness components
No genotype values, dominance model or environmental effects are supplied or inferred.
No causal estimate
The output does not estimate selection from data or provide sampling uncertainty.
Numerical support
Frequencies span zero to one and explicit genotype frequencies must sum to one; components span zero through 10¹² with at least one positive weighted contribution. Positive HWE terms, weighted contributions and normalized shares must remain representable; otherwise an explicit range message asks for equivalent rescaling.
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