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Safeguarding Biodiversity: Preventing Species Extinction

Explore how human activities impact species extinction rates and the importance of protecting wildlife for economic and ecological balance. Learn about endangered and threatened species and methods to prevent premature extinction. Discover ways to conserve habitats and the role of reconciliation ecology in safeguarding biodiversity.

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Safeguarding Biodiversity: Preventing Species Extinction

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  1. Chapter 11 Sustaining Biodiversity: The Species Approach

  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. Updates Online The latest references for topics covered in this section can be found at the book companion website. Log in to the book’s e-resources page at www.thomsonedu.com to access InfoTrac articles. • InfoTrac: Domestic cats serve as add-on predators. Paducah Sun (Paducah, KY), July 26, 2006. • InfoTrac: Invasion of the habitat snatchers. Wichita Eagle, August 6, 2006. • InfoTrac: Group pulls for native Denali plants. Anchorage Daily News, June 26, 2006. • Union of Concerned Scientists: Invasive Species • PBS: Strange Days on Planet Earth • USGS: Nonindigenous Aquatic Species

  4. 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

  5. Animation: Humans Affect Biodiversity PLAY ANIMATION

  6. 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.

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

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

  9. 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

  10. Fig. 11-3, p. 224

  11. 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

  12. 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

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

  14. 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

  15. 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

  16. Video: Penguin Rescue PLAY VIDEO • From ABC News, Biology in the Headlines, 2005 DVD.

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

  18. 34% (51% of freshwater species) Fish 25% Mammals 20% Reptiles 14% Plants 12% Birds Fig. 11-5, p. 225

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

  20. 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

  21. 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).

  22. 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

  23. Animation: Habitat Loss and Fragmentation PLAY ANIMATION

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

  25. 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

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

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

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

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

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

  31. Video: Bachelor Pad at the Zoo PLAY VIDEO • From ABC News, Biology in the Headlines, 2005 DVD.

  32. Case Study: A Disturbing Message from the Birds • Human activities are causing serious declines in the populations of many bird species. Figure 11-9

  33. Black-capped vireo Golden-cheeked warbler Bichnell’s thrush Cerulean warbler Sprague’s pipit Henslow’s sparrow Florida scrub jay California gnatcatcher Bachman’s warbler Kirtland’s warbler Fig. 11-10, p. 232

  34. Video: Bird Species and Birdsongs PLAY VIDEO

  35. Case Study: A Disturbing Message from the Birds • The majority of the world’s bird species are found in South America. • Threatened with habitat loss and invasive species. Figure 11-10

  36. Number of bird species 609 400 200 1 Fig. 11-9, p. 231

  37. INVASIVE SPECIES • Many nonnative species provide us with food, medicine, and other benefits but a a few can wipe out native species, disrupt ecosystems, and cause large economic losses. Kudzu vine was introduced in the southeastern U.S. to control erosion. It has taken over native species habitats. Figure 11-A

  38. INVASIVE SPECIES • Many invasive species have been introduced intentionally. Figure 11-11

  39. Deliberately Introduced Species European starling Purple loosestrife African honeybee (“Killer bee”) Salt cedar (Tamarisk) Nutria Japanese beetle European wild boar (Feral pig) Hydrilla Marine toad (Giant toad) Water hyacinth Fig. 11-11a, p. 234

  40. INVASIVE SPECIES • Many invasive species have been introduced unintentionally. Figure 11-11

  41. Accidentally Introduced Species Eurasian ruffe Sea lamprey (attached to lake trout) Argentina fire ant Brown tree snake Common pigeon (Rock dove) Gypsy moth larvae Asian long-horned beetle Asian tiger mosquito Formosan termite Zebra mussel Fig. 11-11b, p. 234

  42. Fig. 11-11, p. 234

  43. INVASIVE SPECIES • The Argentina fire ant was introduced to Mobile, Alabama in 1932 from South America. • Most probably from ships. • No natural predators. Figure 11-12

  44. INVASIVE SPECIES • Prevention is the best way to reduce threats from invasive species, because once they arrive it is almost impossible to slow their spread. Figure 11-13

  45. What Can You Do? Invasive Species • Do not allow wild animals to escape. • Do not spread wild plants to other areas. • Do not dump the contents of an aquarium into waterways, wetlands, or storm drains. • When camping use wood near your campsite instead of bringing firewood from somewhere else. • Do not dump unused bait into the water. • After dogs visit woods or the water brush them before taking them home. • After each use clean your vehicle, mountain bike, surfboard, kayaks, canoes, boats, tent, hiking boots, and other gear before heading for home. • Empty all water from canoes, kayaks, dive gear, and other outdoor equipment before heading home. • Plant a variety of trees, shrubs, and other plants in your yard to reduce losses from invasive species. • Do not buy plants from overseas or swap them with others using the Internet. Fig. 11-14, p. 236

  46. Characteristics of Successful Invader Species Characteristics of Ecosystems Vulnerable to Invader Species • High reproductive rate, short generation time (r-selected species) • Pioneer species • Long lived • High dispersal rate • Release growth-inhibiting chemicals into soil • Generalists • High genetic variability • Climate similar to habitat of invader • Absence of predators on invading species • Early successional systems • Low diversity of native species • Absence of fire • Disturbed by human activities Fig. 11-13, p. 236

  47. POPULATION GROWTH, POLLUTION, AND CLIMATE CHANGE • Population growth, affluenza, and pollution have promoted the premature extinction of some species. • Projected climate change threatens a number of species with premature extinction.

  48. Pollution • Each year pesticides: • Kill about 1/5th of the U.S. honeybee colonies. • 67 million birds. • 6 -14 million fish. • Threaten 1/5th of the U.S.’s endangered and threatened species. Example of biomagnification of DDT in an aquatic food chain. Figure 11-15

  49. DDT in fish-eating birds (ospreys) 25 ppm DDT in large fish (needle fish) 2 ppm DDT in small fish (minnows) 0.5 ppm DDT in zooplankton 0.04 ppm DDT in water 0.000003 ppm, or 3 ppt Fig. 11-15, p. 237

  50. OVEREXPLOITATION • Some protected species are killed for their valuable parts or are sold live to collectors. • Killing predators and pests that bother us or cause economic losses threatens some species with premature extinction. • Legal and illegal trade in wildlife species used as pets or for decorative purposes threatens some species with extinction.

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