Which definition best captures gene flow?

• A. Movement of individuals or gametes between populations
• B. Movement of alleles within a population due to recombination
• C. Differential survival of individuals with different genotypes
• D. Creation of new alleles by mutation

Answer: (B)

Gene flow is the movement of alleles between populations, usually through the migration of individuals or their gametes. This transfer changes allele frequencies in the populations involved and tends to make them more similar to each other. It does not occur mainly within a single population through recombination, which simply reshuffles existing alleles during sexual reproduction and doesn’t move alleles from one population to another. Natural selection involves different survival of genotypes, and mutation creates new alleles; neither describes the transfer of alleles between populations.