Population Genetics & Selection

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Abstractions about how selection and inheritance shape populations, including equilibrium and fixation dynamics (Hardy-Weinberg principle, fixation, Fisher's fundamental theorem of natural selection), kin-based and social selection (Hamilton's rule, kin selection, inclusive fitness), and mating and sex-ratio dynamics (disassortative mating, Fisher's principle, Haldane's sieve).

11 abstractions in this family — domain-specific abstractions that sit near one another in structural-signature space (k-means over structural-signature embeddings). Each is shown with its short description.

• Disassortative mating — A nonrandom mating pattern in which phenotypically dissimilar individuals pair more often than random expectation.
• Evolutionary Algorithm — A population-based stochastic search family that repeatedly evaluates encoded candidates, selects parents or survivors, creates heritable variants, and replaces population members.
• Fisher's Fundamental Theorem of Natural Selection — Pin the instantaneous speed at which selection improves a population's mean fitness to a single estimable quantity — the additive genetic variance in fitness — and nothing more.
• Fisher's Principle (Sex-Ratio Equilibrium) — Explains the near-1:1 sex ratio of most species not as a group optimum but as the frequency-dependent equilibrium where, whenever one sex is rarer, parents biasing offspring toward it gain more grandchildren until the rarity is erased.
• Fixation (population genetics) — Fixation is the population-genetic transition in which one allele reaches frequency one and all alternative alleles at that locus are lost from the population.
• Haldane's Sieve — Explain why new beneficial mutations that are dominant fix far more often than recessive ones — because while rare an allele sits almost only in heterozygotes, so selection sees a dominant from its first copy but is blind to a masked recessive, which usually drifts to loss before homozygotes form.
• Hamilton's Rule — Predict when an allele for a costly social behaviour spreads by relocating the accounting from organism to gene: it is favoured whenever rB > C — the relatedness-weighted benefit to relatives exceeds the cost to the actor.
• Hardy-Weinberg Principle — Fix the exactly computable genotype baseline (p², 2pq, q²) a diploid population would reach under no evolutionary forces, so that any observed deviation becomes diagnostic evidence of which force — selection, drift, inbreeding, or technical error — is acting.
• Inclusive Fitness — Redefine the quantity natural selection maximizes as an organism's own reproduction plus its effect on relatives' reproduction, each relative weighted by the coefficient of relatedness r, so a costly helping behaviour is favoured whenever rB exceeds C.
• Kin selection — A costly gene can still spread when it makes its carrier help relatives who likely share that gene, as long as the relatedness-weighted benefit to them (rB) outweighs the cost to the actor (C).
• Mutation Accumulation Theory — An evolutionary theory in which weaker selection against later-acting inherited harmful variants lets their burden contribute to senescence.