๐งฌ Allele Drift: Population Genetics
In finite living populations, evolution is driven by both deterministic selection and stochastic random drift. Can you master the mathematical laws governing gene pools?
How to play
- Analyze 8 evolutionary scenarios spanning Hardy-Weinberg equilibrium, Wright-Fisher sampling, bottlenecks, and selective sweeps.
- Experiment with the Interactive Wright-Fisher Population Simulator: step through generations, trigger bottlenecks (N = 10), and watch live allele trajectory curves!
- Calculate carrier frequencies (2pq) and predict allele fixation probabilities.
- Evaluate Nearly Neutral dynamics: determine when random drift overwhelms natural selection based on population size (Ne).
- Tap your answer or press 1โ4. Right answers build a ๐ฅ streak bonus!
About Allele Drift, Hardy-Weinberg & Population Genetics
The mathematical foundation of modern population genetics was established independently in 1908 by English mathematician G. H. Hardy and German physician Wilhelm Weinberg. The Hardy-Weinberg Principle demonstrates that under idealized conditions (infinite population size, random mating, zero mutation, zero migration, and zero natural selection), allele frequencies and genotype proportions remain constant from generation to generation according to the binomial expansion pยฒ + 2pq + qยฒ = 1.
In the 1930s, Sewall Wright and Ronald Fisher recognized that real biological populations are finite. In finite populations, stochastic sampling error during gametogenesis creates genetic driftโunpredictable fluctuations in allele frequencies that cause random fixation of alleles and an irreversible decay in genetic diversity (heterozygosity) at a rate proportional to 1 / (2Ne).
In 1968, Japanese geneticist Motoo Kimura formulated the Neutral Theory of Molecular Evolution, followed by Tomoko Ohta's Nearly Neutral Theory. They showed that the majority of evolutionary changes at the DNA and protein level are not driven by Darwinian selection, but by the random genetic drift of selectively neutral or nearly neutral mutations whose selective coefficient satisfies |s| < 1 / (2Ne).