(N/A) The $Hardy-Weinberg$ principle states that the sum of allelic frequencies in a population remains constant.
Five factors are known to affect $Hardy-Weinberg$ equilibrium:
$(i)$ Gene migration or gene flow: When migration of a section of populations to another place occurs,gene frequencies change in the original as well as in the new population. New genes/alleles are added to the new population and these are lost from the old population.
$(ii)$ Genetic drift: It refers to the elimination of the genes of certain traits when a section of population migrates or dies due to natural calamity.
$(iii)$ Mutation: The sudden heritable change in a gene that alters the genetic makeup of an individual.
$(iv)$ Genetic recombination: It occurs during gamete formation when chromosomes pass from parent to offspring.
$(v)$ Natural selection: It is a phenomenon by which individuals of the population having traits that enable them to grow and reproduce at a higher rate are favoured.