Practice question

Gene flow describes exchange of alleles between populations through migration of individuals followed by interbreeding. Migrants carry allele frequencies characteristic of source population, and their gametes introduce variants into recipient gene pool, directly altering p and q locally. Effective migration reduces genetic divergence, homogenizes populations, can introduce novel variation or spread advantageous alleles across ranges. It opposes genetic drift and selection-driven differentiation that create divergence. Unlike drift which removes variation randomly, gene flow moves existing alleles spatially and is measured quantitatively by migration rate m.