Evolution - Theory to Human Origins

Darwinism, Natural Selection, and Hardy-Weinberg Equilibrium

Darwin's theory of evolution by natural selection remains the central concept in this chapter. NEET questions test the understanding of natural selection types: stabilising selection (reduces variation, favours intermediate forms), directional selection (shifts the mean towards one extreme), and disruptive selection (favours both extremes). Industrial melanism in peppered moths (Biston betularia) is the classic example of directional selection. The Hardy-Weinberg principle provides the mathematical foundation for population genetics: in the absence of evolutionary forces, allele frequencies remain constant across generations. The equation p-squared plus 2pq plus q-squared equals 1 allows calculation of genotype frequencies from allele frequencies. NEET numerical problems typically provide one frequency and ask students to calculate others. Five factors can disturb Hardy-Weinberg equilibrium: gene flow, genetic drift, mutation, natural selection, and non-random mating, each representing a mechanism of evolution.