Which statement is true regarding genetic variation within populations due to gene flow?

Gene flow refers to the transfer of genetic material between populations, typically through the movement of individuals or the exchange of gametes. When gene flow occurs, it introduces new alleles into a population, which can lead to an increase in genetic diversity. This influx of genetic material can help counteract the effects of genetic drift, which tends to reduce genetic variation within smaller, isolated populations.

By boosting the genetic diversity of a population, gene flow can enhance the adaptability of that population to changing environmental conditions. It can also promote what is referred to as gene retention, where alleles that might have been lost in one population are preserved in another, thereby contributing positively to the overall genetic health of the population.

In contrast, the other choices do not accurately reflect the role of gene flow. The notion that it decreases genetic variation is incorrect; rather, its primary effect is to increase variation. Stating that it has no effect overlooks the well-documented impact of gene flow on genetic diversity. Additionally, the assertion that gene flow only applies to large populations ignores that it can occur in populations of all sizes; smaller populations can also experience gene flow when they are in contact with other populations. Thus, the true nature of gene flow is that it plays a crucial role in