AP Biology

Answer: A, The relative change in allelic frequency due to random sampling and chance is called genetic drift. Allelic frequency is the fraction of a population that has a particular genotype.

Key Takeaway: Genetic drift is an important evolutionary process which results in changes in allele frequencies over time. It may cause gene variants to disappear completely or become more common. The process is not driven by natural selection, which makes gene variants more common or less common depending on their reproductive success. The changes due to genetic drift are not driven by environmental or adaptive pressures, and may be beneficial, neutral, or detrimental to reproductive success.