There are many forces that can change the frequency of an allele in the population. They are as follows:
• Natural selection:
Natural selection is a gradual process in which some traits are selected for or against by nature itself. Some traits, which are acquired by mutation can be selected for or against by nature. Those traits which help the species are usually selected.
• Mutation:
Mutations can change the frequency of an allele. When mutations occur in a specific gene it changes its nature, from light to dark. And if it is selected by nature, the frequency of the allele will change.
• Migration:
When species migrate from one place to another, it changes the number of individuals in the existing population. The reduction in size of the population will also change the frequency of the allele.
• Genetic drift:
Genetic drift can be written as sampling errors. The process of genetic drift is a slow process, which will slowly and eventually change the frequency of the alleles in the population.