Which process allows for genetic diversity in a population by introducing new alleles?

Gene flow is the process through which new alleles are introduced into a population, leading to genetic diversity. This occurs when individuals from one population migrate to another and interbreed, carrying different genetic traits with them. By adding new alleles to the gene pool, gene flow can enhance genetic variation, which is critical for the adaptability and survival of a population in changing environments.

In contrast, the other processes also contribute to genetic diversity but in different ways. Genetic drift involves random changes in allele frequencies due to chance events, which can lead to a loss of genetic diversity, especially in small populations. Natural selection is the process whereby certain traits become more common in a population because they confer a survival advantage; it can shape genetic diversity but does not introduce new alleles. Lastly, mutation refers to changes in the DNA sequence that can create new alleles; however, the introduction of these mutations into a population happens at a much lower rate compared to gene flow and is not dependent on the migration of individuals from one population to another.