What is the founder effect and how does it alter genetic variation?

What is the founder effect and how does it alter genetic variation?

• A. A disaster increases population size and variation.
• B. A small group separates from a larger population and establishes a new population; allele frequencies may differ and genetic variation often decreases.
• C. Gene flow introduces new alleles to a population.
• D. Genetic drift cannot occur in small populations.

Answer: (B)

The founder effect is a form of genetic drift that happens when a small group splits off from a larger population and starts a new one. Because only a tiny sample of the original gene pool is carried into the new population, the frequencies of alleles in the new group can be quite different from what they were before. Some alleles present in the large population might be missing entirely in the new population, while others may become more common purely by chance. This often reduces the overall genetic variation in the new population, making its evolutionary path more susceptible to random shifts and environmental changes. Over time, the different starting frequencies can help explain why this isolated group might become genetically distinct from the original population.

The founder effect is a form of genetic drift that happens when a small group splits off from a larger population and starts a new one. Because only a tiny sample of the original gene pool is carried into the new population, the frequencies of alleles in the new group can be quite different from what they were before. Some alleles present in the large population might be missing entirely in the new population, while others may become more common purely by chance. This often reduces the overall genetic variation in the new population, making its evolutionary path more susceptible to random shifts and environmental changes. Over time, the different starting frequencies can help explain why this isolated group might become genetically distinct from the original population.