What does the following equation represent? Explain. p 2 + 2pq + q 2 = 1

p 2 + 2pq + q 2 = 1 is an expression of Hardy-Weinberg equilibrium. The equation of p 2 + 2pq + q 2 = 1 represents the genotypic frequencies of a population when it is in Hardy-Weinberg equilibrium. The Hardy Weinberg law states that the frequency of occurrence of alleles in a population remains constant through generations until any disturbances cause changes in the allelic frequency. The disturbances are mutations and nonrandom mating, genetic drift, sexual selection, etc. In the above equation, allelic frequencies are represented as p and q in a diploid, where p and q represent the frequency of dominant allele A and recessive allele a respectively. The sum total of all allelic frequencies is 1. The frequency of genotypes, AA is p 2 , that of aa is q 2 and that of Aa is 2pq. Hence, p 2 + 2pq + q 2 = 1, which is the expansion of a binomial equation (p + q) 2 .