Which event occurs when one individual or a few individuals colonize a new area, creating a population whose alleles come from the founders?

• A. Genetic Bottleneck
• B. Founder Effect
• C. Gene Flow
• D. Mutation

Answer: (B)

When a new population is started by one or just a few individuals, the genetic makeup of that new group comes from those founders. Because only a small sample of alleles is brought into the new area, the frequencies of those alleles can be quite different from the original population simply by chance. This creates a population whose genetic variation and allele distribution reflect the founders, not the larger source population. That situation is known as the founder effect, a form of genetic drift. It differs from a genetic bottleneck, which happens when a large population is drastically reduced in size but isn’t formed by colonizing a new area; gene flow involves movement between populations bringing new alleles through migration, and mutation adds new alleles directly to a population rather than by sampling from founders.