- The Hardy-Weinberg law states that the gene and genotype frequencies in a Mendelian population remain constant generation after generation if there is no selection, mutation, migration or random drift.
- The frequencies of the three genotypes for a locus with two alleles, say A and a, would be p2 A, 2pq Aa, and q2 aa ; where p represents the frequency of A and q represents the frequency of a allele in the population, and the sum of p and q is one, i.e., p+q=1.
- Such a population would be at equilibrium since the genotypic frequencies would be stable, that is, would not change, from one generation to the next.
- This equilibrium is known as Hardy-Weinberg equilibrium.
- A population is said to be at equilibrium when frequencies of the three genotypes, AA, Aa and aa are p2, 2pq and q2, respectively.
- Whether a population is at equilibrium or not can be easily determined using a chi-square test.
- Hardy-Weinberg law can be easily explained with the help of an example.
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