What is the advantage of having many postglacial lakes for stickleback research?

• A. They make extinction more likely
• B. They allow comparisons across populations to predict environmental influences
• C. They reduce genetic diversity
• D. They limit environmental variation

Answer: (B)

Having many postglacial lakes creates many independent stickleback populations living in different environments. This setup gives researchers natural replicates to compare how populations diverge under varying environmental conditions. By seeing which traits change in parallel across lakes facing similar pressures, scientists can infer which environmental factors are shaping those traits. Conversely, differences among lakes with different conditions help identify which variables matter most. This comparative, multi-population approach also helps separate genetic differences from environmental effects, strengthening predictions about how environments influence stickleback evolution. The other options don’t describe a real advantage: increasing extinction risk isn’t the goal, genetic diversity isn’t inherently reduced, and environmental variation isn’t limited—in fact, it’s broadened across many lakes.