Which of the following describes the bottleneck effect?

• A. A steady increase in population genetic diversity
• B. A rapid reduction in population size followed by recovery
• C. The enhancement of certain alleles in a population over time
• D. A scenario where mutations are eliminated

Answer: (B)

The bottleneck effect is a significant phenomenon in population genetics that occurs when a population undergoes a drastic reduction in size due to environmental events or other crises, like natural disasters, disease, or human activity. This sharp decline in population size can lead to a loss of genetic diversity, as the remaining individuals may not represent the genetic variation that existed in the larger population. After this bottleneck, if the population recovers and begins to grow again, it can result in a population that is less genetically diverse than before the bottleneck occurred.

This concept emphasizes how dramatic population reductions can influence genetic variation and the potential for future adaptability. The recovery phase is crucial, as without a sufficient number of breeding individuals, inbreeding can occur, further diminishing genetic diversity. The correct choice illustrates the essential mechanics of the bottleneck effect accurately, highlighting both the initial reduction in population size and the subsequent recovery.