How does Hardy-Weinberg's expression `(p^(2)+2pq+q^(2)=1)` explain that genetic equilibrium is maintained in population ? List any four factors that can disturb the genetic equilibrium.

Explanation

(i) Hardy of UK and Weinberg of Germany stated that the allete frequencies in a population are stable and are constant from generation to generation in the absence of gene flow, genetic drift, mutation, recombination and natural selection.
(ii) Evolution is a change in the allele frequencies in a population over time. Hence population in Hardy Weinberg is not evolving.
(iii) A large population of beetles, appear in two colours dark grey (black) and light grey, and their colour is determined by .A. gene. .A A. and .A a. beetles are dark grey and .a a. beetles are light grey.
(iv) .A. allele has frequency (p) of 0.3 and .a. allele has frequency (q) of 0.7. Then p+q=1.
(v) If a population is in Hardy Weinberg equilibrium, the genotype frequency can be estimated by Hardy Weinberg equiation.
`(p+q)^(2) =p^(2)+2pq+q^(2)`
`p^(2)` =frequency of AA
2pq = frequency of aa
`q^(2)` = frequency of aa
p=0.3, q=0.7 then,
`p^(2)=(0.3)^(2) (0.7) =0.42=42 % A a`
`q^(2) =(0.7)^(2) 0.49 =49% aa`
Hence the beetle population appears to be in Hardy- Weinberg equilibrium.
(vi) Hardy Weinberg.s assumptions include No mutation- No new alleles are generated by mution nor the genes get duplicated or deleted. Random mating - Every organism gets a chance to mate and the mating is random with each other with no preferences for a particular genotype.
No gene flow - Neither individuals nor their gemetes enter (immigration) or exit (emigration) the population.
Very large population size - The population should be infinite in size.
No matural selection - All alleles are fit to survive and reproduce.
If any one of these assumptions were not met, the population will not be in Hardy- Weinberg equilibrium.