Final answer:
Gene flow is the process of alleles moving in and out of a population through migration, which can lead to microevolutionary changes in the genetic makeup of populations. It introduces new genetic variation and prevents populations from becoming genetically distinct or isolated from each other.
Step-by-step explanation:
Microevolutionary change refers to small-scale changes in the genetic makeup of a population over time. One of the main processes driving microevolution is gene flow. Gene flow involves the movement of alleles (alternative forms of a gene) in and out of a population due to the migration of individuals or gametes.
For example, consider a population of birds that live on two different islands. If some birds from one island migrate to the other island and mate with the birds there, they introduce new alleles into the population. This gene flow can change the genetic structure of the population, leading to new variations.
In addition to introducing new genetic variation, gene flow can also prevent populations from becoming genetically distinct or isolated from each other. By facilitating the exchange of alleles, gene flow can help maintain genetic diversity within a species and prevent the formation of separate species.