What is gene flow in terms of population genetics?

Gene flow refers to the movement of individuals into or out of a population, which can affect the genetic makeup of that population. This process occurs when organisms migrate, reproduce, and introduce their alleles into a new population or, conversely, when they leave one population and carry their alleles away. When individuals from different populations interbreed, their offspring can inherit a mix of genes, leading to changes in allele frequencies within the population.

This phenomenon is crucial in population genetics, as gene flow can increase genetic diversity and reduce differences between populations, potentially impacting evolutionary processes. It can counteract the effects of genetic drift, mutation, and natural selection by introducing new alleles into a population, thereby enriching the gene pool.

In contrast to the other options, gene flow specifically relates to the movement of individuals and the resultant changes in allele frequency, rather than merely being the result of mutations, interspecies gene transfer, or the direct impact of natural selection on gene distribution.