State and explain any three factors affecting allele frequency in populations.

(N/A) $(i)$ Gene migration or gene flow: It involves either emigration or immigration. When a section of a population migrates to another place and population,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. There would be a gene flow if this gene migration happens multiple times.
$(ii)$ Genetic drift: If the same change occurs by chance,it is called genetic drift. Sometimes the change in allele frequency is so different in the new sample of population that they become a different species. The original drifted population becomes founders and the effect is called founder effect.
$(iii)$ Mutation: These are sudden,large,spontaneous,and inheritable changes in the genetic material. Microbial experiments show that pre-existing advantageous mutations when selected will result in the observation of new phenotypes. Over a few generations,this would result in speciation. Natural selection is a process in which heritable variations enabling better survival allow organisms to reproduce and leave a greater number of progeny. Mutations introduce new genes and alleles into the gene pool.