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Name Class Date 7.2 Extinction and Biodiversity Loss Key Concepts Scientists monitor biodiversity closely and have noticed significantly higher than normal extinction rates in recent decades. Habitat change and loss, invasive species, pollution, overharvesting, and climate change are the major causes of biodiversity loss. Vocabulary Preview Define each vocabulary term in your own words. Then, write yourself a quick note on how you will remember each. One term has been done for you. Term Definition How I Remember Extirpation Endangered species A species that has a high risk of extinction Threatened species Habitat fragmentation Poaching 118 An endangered species is in danger of going extinct. Name Class Date Reading Strategy Fill in the table to preview the lesson. Then, in the space that follows the table, write one sentence to explain what you think this lesson will be about. What is the title of this lesson? What are the vocabulary terms for this lesson? What are the key concepts for the two main sections of this lesson? What do the photos depict? What do the diagrams show? EXTENSION Use the Internet to research threatened and endangered species in your state. On a separate sheet of paper, name and describe at least one plant and one animal that is threatened or endangered. Biodiversity at Risk 1. Is extinction a natural process? Explain. 2. Compare and contrast extinction with extirpation. 119 Name Class Date 3. How does the background rate of extinction differ from mass extinctions? 4. Which type of species is more likely to become extinct, an endangered species or a threatened species? Explain. Causes of Biodiversity Loss 5. Fill in the cause-and-effect diagram with a short description that explains how each process leads to loss of biodiversity. Habitat Alteration Invasive Species Biodiversity Loss Overharvesting Pollution 120 Name Class Date 6. How do the effects of climate change differ from the effects of habitat alteration, invasive species, overharvesting, and pollution? 7. A conservation plan could proceed with a single 20-square kilometer habitat preserve or with two habitat preserves, measuring a total of 20 square kilometers combined. Which preserve format would support more species? Explain. 8. What human activities lead to habitat loss? 9. What are “habitat islands,” and how do they occur? 10. How did studies of oceanic islands help scientists understand the effect of habitat fragmentation on species diversity? 11. What is the greatest cause of biodiversity loss today? 12. What factors determine whether nonnative species are considered invasive? 13. List two nonnative species—one that is invasive, and another that is not invasive. 121 Name Class Date 14. Many protected animals are lost to poaching. What is a main motivation behind poaching? 15. How do warming temperatures affect animals that live in cold climates? Answer the questions to test your knowledge of lesson concepts. You can check your work using the answers on the bottom of the page. 16. What evidence suggests that we could be experiencing a sixth mass extinction? 17. What information is represented by the Living Planet Index? 18. List five causes of biodiversity loss. 19. What is the greatest cause of biodiversity loss today? Explain. 122