Write a short note on the Hardy-Weinberg principle.

(N/A) In $1908$,$G.H. Hardy$ and $W. Weinberg$ established a mathematical relationship to study gene frequencies,known as the Hardy-Weinberg principle.
This principle states that allele frequencies in a population are stable and remain constant from generation to generation,meaning the gene pool remains constant. This state is called genetic equilibrium.
Mathematically,the sum total of all allelic frequencies is $1$. For a gene with two alleles $A$ and $a$ having frequencies $p$ and $q$ respectively,the frequency of individuals in a population is represented by the binomial expansion $(p + q)^2 = p^2 + 2pq + q^2 = 1$.
Here,$p^2$ represents the frequency of homozygous dominant individuals $(AA)$,$q^2$ represents the frequency of homozygous recessive individuals $(aa)$,and $2pq$ represents the frequency of heterozygous individuals $(Aa)$.
When the measured frequency differs from the expected values,the difference indicates the extent of evolutionary change. Any disturbance in this equilibrium,such as a change in allele frequency,is interpreted as the result of evolution.
Five factors are known to affect the Hardy-Weinberg equilibrium: gene migration (gene flow),genetic drift,mutation,genetic recombination,and natural selection.