A component of genetic drift theory, stating that new populations that become isolated from the parent population carry only the genetic variation of the founders.

• A. Genetic drift
• B. Genetic bottleneck
• C. Sexual selection
• D. Founder effect

Answer: (D)

Founder effect is a form of genetic drift in which a new population is started by a small group of individuals, so the new gene pool contains only the alleles present in those founders. Because only a tiny sample of the parent’s genetic variation makes it into the new population, some alleles are lost and others can become more common just by chance. This matches the idea that the isolated population carries only the founders’ genetic variation, not the full range from the original population. For example, a few individuals colonizing an island bring with them a subset of alleles, and those frequencies shift over time independently from the parent group. In contrast, a genetic bottleneck reduces variation due to a drastic population size drop affecting the whole population, not an isolated founding event, and sexual selection involves nonrandom mating based on traits rather than the initial gene pool of a new population.