Explain it to me like I'm…High-school biology — proper terms explained
M8
Module 8 · Genetics and society
Genetics and society
Population genetics, human evolution, ethics, privacy, and eugenicsEugenicsA discredited movement, coined by Francis Galton in 1883, that aimed to "improve" human populations by controlling reproduction. Applied as coercive state policy in the early 20th century, including forced sterilisation and Nazi racial programmes, causing enormous harm. A warning against misusing genetic knowledge. history: Module 8.
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When you look at a whole population instead of one gameteGameteA haploid reproductive cell (egg or sperm) that fuses at fertilization., you track how alleleAlleleAlternative forms of a gene at the same spot on a chromosome. frequencies, the proportion of each geneGeneA stretch of DNA that codes for a functional product, usually a protein. version, change across generations. Under random matingRandom matingPartners are chosen without regard to genotype. Required for Hardy–Weinberg equilibrium at a single locus., the math follows predictable rules: frequencies stay constant when nothing else is pushing the population. Natural selectionNatural selectionSurvival and reproduction differences that change allele frequencies over time. can shift them when some genotypes survive or reproduce better than others. Genetic driftGenetic driftRandom changes in allele frequency due to chance in small populations. can do the same through sampling error in finite populations, essentially random luck in who passes genes on. Both forces can move frequencies over time, and drift can be especially dramatic in small populations.
Hardy–WeinbergHardy–Weinberg equilibriumModel where allele frequencies stay constant: AA = p², Aa = 2pq, aa = q².: random matingRandom matingPartners are chosen without regard to genotype. Required for Hardy–Weinberg equilibrium at a single locus. only, with no selection and an infinite-population approximation (so drift is absent)
Current p (freq. A)68.5%
Current q (freq. a)31.5%
H-W expected AA72 (36.0%)
H-W expected Aa96 (48.0%)
**Allele frequency** (p and q) tracked across successive generations; watch how each version rises, falls, or holds steady
**Genotype composition** at the final generation, the proportions of **AA, Aa, and aa** individuals in the population
**Hardy–Weinberg equilibrium**
If mating is random and there is no mutationMutationA change in the DNA sequence of a cell: from a single base substitution to large chromosomal rearrangements. Most mutations are neutral; some disrupt gene function and cause disease; rarely a mutation is beneficial. Germline mutations can be inherited; somatic mutations stay within the individual., migration, selection, or drift, alleleAlleleAlternative forms of a gene at the same spot on a chromosome. frequencies stay constant from the first generation onward. GenotypeGenotypeThe alleles an organism carries at a locus (e.g. AA, Aa, aa). frequencies settle into Hardy–WeinbergHardy–Weinberg equilibriumModel where allele frequencies stay constant: AA = p², Aa = 2pq, aa = q². proportions: p² AA, 2pq Aa, q² aa, after one generation of random matingRandom matingPartners are chosen without regard to genotype. Required for Hardy–Weinberg equilibrium at a single locus., even though the alleleAlleleAlternative forms of a gene at the same spot on a chromosome. counts p and q are already fixed immediately. This equilibrium is a useful baseline; real populations deviate whenever evolutionary forces act.
With your settings, the allele frequencyAllele frequencyProportion of alleles in a population that are a specific variant (p and q). p should stay near 60% from generation to generation. Run the simulation again to confirm the population remains in equilibrium.
