How does gene flow affect genetic diversity in the recipient population?

• A. It increases genetic diversity in the recipient population.
• B. It reduces genetic diversity in the recipient population.
• C. It has no effect on genetic variation.
• D. It always leads to speciation.

Answer: (A)

Gene flow moves alleles from one population into another. When individuals from a different population enter and breed, they bring new alleles into the recipient’s gene pool. That introduction of new genetic material increases the variety of alleles and genotypes present, boosting the genetic diversity within the recipient population. This added diversity provides more raw material for natural selection to act on and can help the population adapt to changing conditions.

It’s not accurate to say it has no effect, nor that it reduces diversity in general—the typical outcome is an increase in within-population diversity. And while gene flow can reduce differences between populations, it does not always lead to speciation.