Gene flow is transfer of genes from one population to another.
Factors affecting gene flow:
1. Mobility: gene flow is lower in species having low mobility or dispersal.
2. Distance: When there is long distances between populations then it results in low gene flow.
3. Population size: Small population size results in low gene flow.
4. Social structure: It is highly affected by social structure because of genetic variation.
5. Endogamous populations: Endogamous population results in low gene flow because they allow only individuals of their group and caste. Therefore, new genetic material is not introduced into the population and thus results in low gene flow.
6. Exogamous population: It allows more genetic diversity and thus more gene flow as they allow individuals outside their group and caste.
7. Reproductively isolated: Reproductively isolated is defined as the inability of species to breed within the related species. Therefore, it allows less gene flow as distant populations results in low genetic difference.