What effect does gene flow have over time on populations?

Gene flow refers to the transfer of genetic material between separate populations, typically through the movement of individuals or their gametes (like pollen). When gene flow occurs, it introduces new alleles into a population, which can lead to a combination of genetic material that wasn't previously present. Over time, this process tends to homogenize genetic differences between populations.

As individuals from different populations interbreed, the genetic distinctions that might have existed due to different evolutionary pressures or adaptations begin to diminish. This mixing increases the genetic similarity of the populations, effectively reducing the genetic variance among them.

In this way, the impact of gene flow is significant in shaping genetic diversity across populations; rather than leading to isolation or increasing differences, it facilitates genetic similarities and shared traits within a broader geographic scope.