Hardy-Weinberg equilibrium requires no selection, mutation, migration, genetic drift or non-random mating in a large population in evolving populations in evolving populations.
Coverage 2012–2025 · Updated 16 Jul 2026
Hardy–Weinberg equilibrium assumes a large population, random mating, no migration, no mutation and no selection.
These conditions prevent systematic changes in allele frequencies or sampling noise. Violating one condition can make observed genotype frequencies depart from expectation.
Check each assumption before using an equilibrium calculation as a biological conclusion.; separate variation, selection, inheritance and time
A small isolated population can deviate because drift acts strongly even if no selection is present. This gives a concrete prediction from the stated population.
A departure does not reveal which assumption failed; independent evidence is needed. Interpret the result within the stated selection model and evidence limits.
This objective is assessed through structured response, commonly using State / Identify.
State / Identify
Build the answer around this relationship: Hardy-Weinberg equilibrium is a null model for no evolution.
Representative question
State two assumptions made when using the Hardy-Weinberg equation.
1.
HL D4.1 turns selection into measurable population genetics. A gene pool changes when allele frequencies shift. Hardy-Weinberg gives a no-evolution baseline; selection graphs, isolated populations, artificial selection, and resistance show how forces move populations away from that baseline.
HL population-genetics questions ask students to quantify or model evolution. The answer starts with the gene pool and allele frequencies, then uses the model or selection graph to decide whether the population is at equilibrium or being shifted by selection, mutation, migration, drift, artificial selection, or isolation.
