Gene flow interacts with natural selection by:

• A. Always preventing adaptation
• B. Providing new genetic variation for selection to act on
• C. Eliminating all mutations
• D. Fixing alleles in populations without variation

Answer: (B)

Gene flow brings new alleles into a population, increasing the genetic variation that natural selection can act on. When individuals migrate or pollen/seed moves between populations, alleles that were rare or absent can enter the gene pool. Natural selection then has more material to work with, allowing beneficial variants to spread and less fit ones to be removed. This means gene flow can facilitate adaptation by introducing advantageous traits, rather than always hindering it or eliminating mutations. It also explains why populations connected by movement of individuals often share genetic similarities.