Home▸Molecular Biology▸Balancing Selection: Heterozygote Advantage

Balancing Selection: Heterozygote Advantage

Interactive Wright-Fisher population genetics simulator: watch a two-allele population converge on a stable equilibrium frequency under heterozygote-advantage selection, with adjustable selection coefficients, population size and genetic drift, and live allele-frequency tracking in 3D.

Molecular Biology3DAdvanced60 FPS📱 Mobile-adapted⇄ 2D version

This simulator runs a real discrete-generation Wright-Fisher population genetics model for a single gene with two alleles, A and a. When the heterozygote Aa carries a fitness advantage over both homozygotes — overdominance, or heterozygote advantage — directional selection cannot fix either allele. Instead the population is pulled toward a stable internal equilibrium frequency q* = s₁/(s₁+s₂), the classic mechanism behind human polymorphisms such as the sickle-cell allele in malaria-endemic populations. Each generation, a population of N individuals is rendered as a 3D field of instanced spheres colored by genotype; a live trajectory line tracks the allele frequency against the theoretical equilibrium, and the population-size control lets you see genetic drift pull small populations away from the deterministic curve.

⚙ Under the hood

A Wright-Fisher population genetics simulator showing how selection against both homozygotes at a two-allele locus drives allele frequency to a stable equilibrium instead of fixation, with adjustable selection coefficients, population size and genetic drift.

population geneticsnatural selectionheterozygote advantagegenetic driftWright-Fisher modelallele frequency

3D · Three.js / WebGL renderer · 60 FPS target · runs fully client-side, no install