Final answer:
Genetic drift, geographic isolation, and gene flow are the factors that can affect the allele frequency of a population.
Step-by-step explanation:
When there is little gene flow, the allele frequency of a population can be affected by several factors. One of these factors is genetic drift, which is the effect of chance on allele frequencies. Genetic drift is more pronounced in small populations and can lead to the loss of certain alleles. Another factor is geographic isolation, which prevents the free flow of alleles between populations. Over time, different populations can evolve independently and have distinct allele frequencies. Lastly, gene flow itself, when individuals migrate in or out of a population, can also impact allele frequencies.