Bottleneck Effect: Examples and Consequences for Biodiversity

📚 Quick Study Guide

• 🧬 The bottleneck effect is a sharp reduction in the size of a population due to environmental events (such as famines, earthquakes, floods, fires, disease, or droughts) or human activities (such as genocide).
• 📉 It results in a significant decrease in the gene pool of the population because many alleles, or gene variants, that were present in the original population are lost.
• 🐾 The surviving population is not representative of the original. Random chance plays a large role in determining which individuals survive and reproduce.
• 🌱 This can lead to a loss of genetic diversity, which reduces the ability of the population to adapt to future environmental changes or diseases.
• 🐻‍❄️ Examples include: Northern elephant seals and cheetahs, where the modern populations show very little genetic variation due to past bottleneck events.
• 📝 Consequences can include increased susceptibility to diseases, reduced reproductive success, and a higher risk of extinction.

🧪 Practice Quiz

1. What is the bottleneck effect?
1. A gradual increase in population size.
2. A sharp reduction in population size due to a catastrophic event.
3. The migration of a large population to a new habitat.
4. The natural selection of advantageous traits.
2. Which of the following is a consequence of the bottleneck effect on biodiversity?
1. Increased genetic diversity.
2. Reduced susceptibility to diseases.
3. Loss of genetic variation.
4. Enhanced reproductive success.
3. Which factor does NOT typically cause a population bottleneck?
1. A sudden disease outbreak.
2. Consistent and stable environmental conditions.
3. A major natural disaster.
4. Overhunting by humans.
4. What role does random chance play in the bottleneck effect?
1. It determines which traits are selected for.
2. It influences which individuals survive and reproduce.
3. It increases the population size.
4. It prevents genetic drift.
5. Which of the following is an example of a species that has experienced a bottleneck effect?
1. Fruit flies.
2. Cheetahs.
3. Rabbits.
4. Earthworms.
6. How does a bottleneck effect impact a population's ability to adapt to future changes?
1. It increases their adaptability.
2. It reduces their adaptability.
3. It has no impact on their adaptability.
4. It makes them more resistant to mutations.
7. What is the primary concern regarding populations that have gone through a bottleneck effect?
1. Increased competition for resources.
2. Higher risk of extinction.
3. Enhanced genetic diversity.
4. Greater resistance to diseases.