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Chapter 9

Chapter 9. Sustaining Biodiversity: The Species Approach Pgs. 183-194. Chapter Overview Questions. How do biologists estimate extinction rates, and how do human activities affect these rates? Why should we care about protecting wild species? Which human activities endanger wildlife?

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Chapter 9

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  1. Chapter 9 Sustaining Biodiversity: The Species Approach Pgs. 183-194

  2. Chapter Overview Questions • How do biologists estimate extinction rates, and how do human activities affect these rates? • Why should we care about protecting wild species? • Which human activities endanger wildlife? • How can we help prevent premature extinction of species? • What is reconciliation ecology, and how can it help prevent premature extinction of species?

  3. Core Case Study: The Passenger Pigeon - Gone Forever • Once the most numerous bird on earth. • In 1858, Passenger Pigeon hunting became a big business. • By 1900 they became extinct from over-harvest and habitat loss. Figure 11-1

  4. SPECIES EXTINCTION • Species can become extinct: • Locally: A species is no longer found in an area it once inhabited but is still found elsewhere in the world. • Ecologically: Occurs when so few members of a species are left they no longer play its ecological role. • Globally (biologically): Species is no longer found on the earth.

  5. Global Extinction • Some animals have become prematurely extinct because of human activities. Figure 11-2

  6. Aepyornis (Madagascar) Passenger pigeon Great auk Dodo Dusky seaside sparrow Fig. 11-2, p. 223

  7. Endangered and Threatened Species: Ecological Smoke Alarms • Endangered species: so few individual survivors that it could soon become extinct. • Threatened species: still abundant in its natural range but is likely to become endangered in the near future. Figure 11-3

  8. Fig. 11-3, p. 224

  9. Florida manatee Kirkland’s warbler Grizzly bear Knowlton cactus African elephant Swallowtail butterfly Humpback chub Utah prairie dog Siberian tiger Golden lion tamarin Fig. 11-3, p. 224

  10. Giant panda Blue whale Whooping crane Northern spotted owl Black-footed ferret Mountain gorilla Florida panther California condor Hawksbill sea turtle Black rhinoceros Fig. 11-3, p. 224

  11. SPECIES EXTINCTION • Some species have characteristics that make them vulnerable to ecological and biological extinction. Figure 11-4

  12. Characteristic Examples Blue whale, giant panda, rhinoceros Blue whale, giant panda, Everglades kite Many island species, elephant seal, desert pupfish Bengal tiger, bald eagle, grizzly bear Blue whale, whooping crane, sea turtles Many island species, African violet, some orchids Snow leopard, tiger, elephant, rhinoceros, rare plants and birds California condor, grizzly bear, Florida panther Low reproductive rate (K-strategist) Specialized niche Narrow distribution Feeds at high trophic level Fixed migratory patterns Rare Commercially valuable Large territories Fig. 11-4, p. 225

  13. SPECIES EXTINCTION • Scientists use measurements and models to estimate extinction rates. • The International Union for the Conservation of Nature and Natural Resources (IUCN) publishes an annual Red List, listing the world’s threatened species. • The 2004 Red List contains 15,589 species at risk for extinction. Figure 11-5

  14. SPECIES EXTINCTION • Percentage of various species types threatened with premature extinction from human activities. Figure 11-5

  15. 34% (51% of freshwater species) Fish 25% Mammals 20% Reptiles 14% Plants 12% Birds Fig. 11-5, p. 225

  16. SPECIES EXTINCTION • Scientists use models to estimate the risk of particular species becoming extinct or endangered. Figure 11-6

  17. Number of species existing Effects of a 0.1% extinction rate 5,000 extinct per year 5 million 14 million 14,000 extinct per year 50 million 50,000 extinct per year 100 million 100,000 extinct per year Number of years until one million species are extinct Fig. 11-6, p. 226

  18. IMPORTANCE OF WILD SPECIES • We should not cause the premature extinction of species because of the economic and ecological services they provide. • Some believe that each wild species has an inherent right to exist. • Some people distinguish between the survival rights among various types of species (plants vs. animals).

  19. HABITAT LOSS, DEGRADATION, AND FRAGMENTATION • Conservation biologists summarize the most important causes of premature extinction as “HIPPO”: • Habitat destruction, degradation, and fragmentation • Invasive species • Population growth • Pollution • Overharvest

  20. HABITAT LOSS, DEGRADATION, AND FRAGMENTATION • The greatest threat to a species is the loss, degradation, and fragmentation of where it lives. Figure 11-7

  21. Habitatloss Pollution Overfishing Habitat degradation and fragmentation Commercial hunting and poaching Climate change Introducingnonnative species Sale of exotic petsand decorative plants Predator and pest control Secondary Causes • Population growth • Rising resource use • No environmental accounting • Poverty Basic Causes Fig. 11-7, p. 229

  22. HABITAT LOSS, DEGRADATION, AND FRAGMENTATION • Reduction in ranges of four wildlife species, mostly due to habitat loss and overharvest. Figure 11-8

  23. Indian Tiger Range 100 years ago Range today (about 2,300 left) Fig. 11-8a, p. 230

  24. Black Rhino Range in 1700 Range today (about 3,600 left) Fig. 11-8b, p. 230

  25. African Elephant Probable range 1600 Range today Fig. 11-8c, p. 230

  26. Asian or Indian Elephant Former range Range today (34,000–54,000 left) Fig. 11-8d, p. 230

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