Evolution and gene frequencies — A/L Biology

A. Hardy-Weinberg Equilibrium Definition: The Hardy-Weinberg equilibrium is a principle stating that the genetic variation in a population will remain constant from one generation to the next in the absence of disturbing factors. Explanation: This principle provides a mathematical model that describes how allele frequencies remain stable in a population over time when specific conditions are met. It serves as a null hypothesis for evolutionary studies - if allele frequencies change, evolution is occurring. The equilibrium is expressed through the equation p² + 2pq + q² = 1, where p and q represent the frequencies of two alleles in a population. This model helps scientists determine whether evolutionary forces are acting on a population by comparing observed genetic frequencies with expected frequencies under equilibrium conditions. Think of it as: Imagine a perfectly balanced scale where weights on both sides remain exactly the same over time unless someone adds or removes weights - the Hardy-Weinberg equilibrium is like this perfect balance in genetic frequencies.