Gene flow

Definition

The transfer of alleles or genetic material from one population to another via dispersal and interbreeding. Gene flow homogenizes allele frequencies among populations, counteracts genetic drift, and can introduce adaptive genetic variation or constrain local adaptation and speciation depending on its rate and pattern.

Etymology

Example

In fragmented landscapes, gene flow between isolated butterfly metapopulations depends on the dispersal capacity of individuals; even one migrant per generation can prevent genetic divergence by drift, while restricted gene flow may allow local adaptation to host-plant chemistry.

Synonyms

• migration (population genetics)
• allele flow

Related Terms

• genetic drift
• population structure
• effective population size
• local adaptation
• speciation
• metapopulation
• Dispersal
• inbreeding depression
• outbreeding depression
• isolation by distance

Usage Notes

Distinguished from simple physical dispersal: gene flow requires successful reproduction in the recipient population. Rates are often asymmetric (source–sink dynamics) and scale with geographic distance, barriers, and organismal vagility. In conservation contexts, managed gene flow (translocation) is debated for threatened insects to rescue genetic diversity versus risks of disrupting co-adapted gene complexes.