Hardy–Weinberg Equilibrium Holds Only Under Five Strict ConditionsThe Hardy–Weinberg principle predicts that allele and genotype frequencies stay constant across generations.This only holds if five conditions are met, and breaking any one means the population is evolving.The Five Conditions, and What Breaking Each One DoesNo mutationNew alleles would change allele frequencies.Random matingNon-random mating shifts genotype frequencies toward certain combinations.No gene flowMigration would add or remove alleles.Large populationIn a small population, genetic drift changes frequencies by chance.No natural selectionSelection lets favoured phenotypes contribute more alleles to the next generation.NoteAt least one condition is almost always broken in nature.So true Hardy–Weinberg equilibrium is essentially a theoretical baseline to compare real populations against.Comparing Observed and Expected Frequencies Detects EvolutionIf observed genotype frequencies match the equation's predictions, the population is at equilibrium.If they deviate, one or more evolutionary forces are acting, and the equation points to which are worth investigating.Active recallList the five conditions for Hardy–Weinberg equilibrium.What does non-random mating do to genotype frequencies?Why is genetic drift only a problem in small populations?How can comparing observed and expected frequencies reveal that a population is evolving?
