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Chapter 7

Chapter 7. Sustaining Biodiversity: The Species Approach. 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 7

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  1. Chapter 7 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.

  5. 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.

  6. Global Extinction • Some animals have become prematurely extinct because of human activities.

  7. Aepyornis (Madagascar) Passenger pigeon Great auk Dodo Dusky seaside sparrow

  8. 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.

  9. Florida manatee Kirkland’s warbler Grizzly bear Knowlton cactus African elephant Swallowtail butterfly Humpback chub Utah prairie dog Siberian tiger Golden lion tamarin

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

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

  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

  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.

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

  15. 34% (51% of freshwater species) Fish 25% Mammals 20% Reptiles 14% Plants 12% Birds

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

  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

  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.

  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

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

  23. Indian Tiger Range 100 years ago Range today (about 2,300 left)

  24. Black Rhino Range in 1700 Range today (about 3,600 left)

  25. African Elephant Probable range 1600 Range today

  26. Asian or Indian Elephant Former range Range today (34,000–54,000 left)

  27. Case Study: A Disturbing Message from the Birds • Human activities are causing serious declines in the populations of many bird species.

  28. 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

  29. 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.

  30. Number of bird species 609 400 200 1

  31. 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.

  32. INVASIVE SPECIES • Many invasive species have been introduced intentionally.

  33. INVASIVE SPECIES • Many invasive species have been introduced unintentionally.

  34. 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

  35. 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

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

  37. 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.

  38. 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.

  39. 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

  40. 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.

  41. 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.

  42. 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

  43. 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.

  44. OVEREXPLOITATION • Rhinoceros are often killed for their horns and sold illegally on the black market for decorative and medicinal purposes.

  45. Case Study: Rising Demand for Bushmeat in Africa • Bushmeat hunting has caused the local extinction of many animals in West Africa. • Can spread disease such as HIV/AIDS and ebola virus.

  46. PROTECTING WILD SPECIES: LEGAL AND ECONOMIC APPROACHES • International treaties have helped reduce the international trade of endangered and threatened species, but enforcement is difficult. • One of the most powerful is the 1975 Convention on International Trade of Endangered Species (CITES). • Signed by 169 countries, lists 900 species that cannot be commercially traded.

  47. Case Study: The U.S. Endangered Species Act • One of the world’s most far-reaching and controversial environmental laws is the 1973 U.S. Endangered Species Act (ESA). • ESA forbids federal agencies (besides defense department) to carry out / fund projects that would jeopardize an endangered species. • ESA makes it illegal for Americans to engage in commerce associated with or hunt / kill / collect endangered or threatened species.

  48. Case Study: The U.S. Endangered Species Act • Biodiversity hotspots in relation to the largest concentrations of rare and potentially endangered species in the U.S.

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