Certain factors that affect Hardy-Weinberg equilibrium and leads to evolution are as follow:
(i)Gene Migration or Gene Flow
New genes or alleles are added to new population and are lost from old population inturn changing the gene frequencies. This is called gene migration. When gene migration happens multiple times, it is called gene flow.
It refers to a random gene frequency change and occurs only by chance. At times, 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 the founder and the effect is called founder effect.
The sudden change in appearance or variations in an individual or a population are called mutations. They lead to the new phenotypes.
Though mutations are random and occur at very slow rates, they are sufficient to create considerable genetic variations for speciation to occur.
When the alleles of parental linkage groups separate and new associations of alleles are formed due to crossing over during gametogenesis. This process is known as genetic recombination.