Which statement correctly describes the founder effect?

Which statement correctly describes the founder effect?

• A. A large group of individuals from a population start a new population with the same allele frequencies as the original.
• B. Migration between populations has no impact on allele frequencies.
• C. A few individuals from a population start a new population with a different allele frequency than the original populations.
• D. Genetic drift always increases genetic diversity in a small population.

Answer: (C)

The founder effect is a form of genetic drift that happens when a small number of individuals start a new population. Because the new group only carries a tiny sample of the original gene pool, the allele frequencies in the new population can differ from those in the source population. This randomness in sampling can also reduce genetic diversity in the new population, and some alleles may become common or disappear purely by chance. The scenario described—just a few individuals founding a new population with a different allele frequency than the original populations—best captures this idea. In contrast, having a large group start with the same frequencies wouldn’t show this sampling effect; gene flow between populations can alter allele frequencies too, and genetic drift in small populations tends to decrease, not increase, diversity.

The founder effect is a form of genetic drift that happens when a small number of individuals start a new population. Because the new group only carries a tiny sample of the original gene pool, the allele frequencies in the new population can differ from those in the source population. This randomness in sampling can also reduce genetic diversity in the new population, and some alleles may become common or disappear purely by chance. The scenario described—just a few individuals founding a new population with a different allele frequency than the original populations—best captures this idea. In contrast, having a large group start with the same frequencies wouldn’t show this sampling effect; gene flow between populations can alter allele frequencies too, and genetic drift in small populations tends to decrease, not increase, diversity.