State and explain Hardy Weinberg’s Principle

Explanation

Hardy-Weinberg principle state :
(i) Allele frequencies in a population are stable and is constant from generation to generation.
(ii) The-gene poor (total genes and their alleles in a population) remains constant. This is called genetic equilibrium.
(iii) Sum total of all the allelic frequencies is 1. For example, in a diploid individual, p and q represent the frequency of allele A and allele a. The frequency of AA individuals in a population is simply `p^(2)`. Similarly, the frequency of aa is `q^(2)` and of Aa is 2pq. Hence, `p^(2)+ 2pg+q^(2)=1`.This is a binomiai expansion of `(p+q)^(2)`.
When frequency, measured, differs from expected values, the difference (direction) indicates the extent of evolutionary change. Disturbance in genetic equilibrium or Hardy Weinberg equilibrium i.e., change of frequency of alleles in Ta population would then be interpreted "as resulting in evolution.