What is the Hardy-Weinberg equation?

2 Answers

This is an equation used to determine if a population is evolving or not.


The Hardy-Weinberg principle is not generally found in nature because it requires certain conditions in an environment. These conditions are the absence of the things that can cause evolution . In other words, if no mechanisms of evolution are acting on a population, evolution will not occur--the gene pool frequencies will remain unchanged. However, since it is highly unlikely that any of these seven conditions, let alone all of them, will happen in the real world, evolution is the inevitable result. The conditions are:

a. No mutation
b. No immigration or emigration
c. Infinitely large population size
d. No natural selection
e. All members of the population breed
f. All mating is totally random
g. Everyone produces the same number of offspring.
Hardy-Weinberg principle can be illustrated mathematically with the equation: p2+2pq+q2 = 1, where ‘p’ and ‘q’ represent the frequencies of alleles. P added to q always equals one (100%). The principle behind it is that, in a population where certain conditions are met (see below), the frequency of the alleles in the gene pool will be constant.

To read more about the Hardy-Weinberg Theory and Equation, check out this page from Nature.

p2 + 2pq + q2 = 1.


  1. By the help of the Hardy-Weinberg equation, the geneticists examine and calculate the locus, which cotains two alleles. The two alleles are designated as A and a.
  2. This equation is expressed as p2 + 2pq + q2 = 1. Where p is the frequency of the "A" allele and q is the frequency of the "a" allele in the population.
  3. The frequencies of genes remain constant in the population.