What is Gene flow? Give an example.

Hint: Gene flow is the mechanism of the movement of gene or allele from one population to another population belonging to the same species. It is also known as gene migration or allele flow. Gene flow is a result of interbreeding between two different populations of the same species. Gene flow leads to evolution.

Complete explanation:
Gene flow can be explained by the following example. Consider two populations of beetles, population A has a genotype XX whereas population B has a genotype xx. These two populations are on either side of a hill. Due to some environmental conditions, one beetle from the population B with genotype xx migrates to the other side of the hill and mingles with population A. When this beetle from population B breeds with a beetle from population A, the genetic material is transferred and gene flow has taken place. There is no abrupt change in the genetic makeup of the offspring. But it can be observed that there is a change in the proportion of the alleles that has been transferred.

Additional information:
Gene flow can be affected by different factors of the environment. The factors can be a physical barrier where no two populations of the same species can migrate due to a mountain range or an ocean. It can also be a reproductive barrier due to different breeding seasons.

Note:
Gene flow is important because of its evolutionary force. Gene flow causes variations in a population. Gene flow can be considered important because in some cases, the allele with undesired trait can be completely eliminated from a population, when the flow is continuous.