Gene frequencies in a population do not remain the same and are always changing. Scientists have classified the causes of this change into
- natural selection
Mutations are very rare and changes in gene frequencies due to this are very slow.
When organisms of a species that have formed a distinct group interact with organisms of other groups, they are able to transfer some characteristics that they have and which are not present in the other group. This is referred to as migration.
When genes are passed on from parent to offspring there is a small amount of variation which can be attributed to probability. These are totally random in nature and are known as genetic drift.
One of the leading causes of changes in gene frequency is natural selection. Organisms of a species that have traits which are favorable for their survival in a particular environment are in a better position to pass on their genes to the next generation than organisms which do not have these traits. This slowly alters the gene frequency with the genetic information favorable for the advancement of the species getting engrained in the genes of all organisms of the species.