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Chapter 9

Chapter 9. Sustaining Biodiversity: The Species Approach Pg. 195 - 211. 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 Pg. 195 - 211

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

  4. 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

  5. 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

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

  7. 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

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

  9. 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

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

  11. 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

  12. Fig. 11-11, p. 234

  13. 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

  14. 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

  15. 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

  16. 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

  17. 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.

  18. 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

  19. 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

  20. 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.

  21. OVEREXPLOITATION • Rhinoceros are often killed for their horns and sold illegally on the black market for decorative and medicinal purposes. Figure 11-16

  22. 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. Figure 11-17

  23. 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.

  24. 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.

  25. 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. Figure 11-18

  26. Top Six Hot Spots 1 Hawaii 2 San Francisco Bay area 3 Southern Appalachians 4 Death Valley 5 Southern California 6 Florida Panhandle Concentration of rare species Moderate Low High Fig. 11-18, p. 241

  27. Endangered Species • Because of scarcity of inspectors, probably no more than 1/10th of the illegal wildlife trade in the U.S. is discovered. Figure 11-19

  28. Endangered Species • Congress has amended the ESA to help landowners protect species on their land. • Some believe that the ESA should be weakened or repealed while others believe it should be strengthened and modified to focus on protecting ecosystems. • Many scientists believe that we should focus on protecting and sustaining biodiversity and ecosystem function as the best way to protect species.

  29. PROTECTING WILD SPECIES: THE SANCTUARY APPROACH • The U.S. has set aside 544 federal refuges for wildlife, but many refuges are suffering from environmental degradation. Pelican Island was the nation’s first wildlife refuge. Figure 11-20

  30. PROTECTING WILD SPECIES: THE SANCTUARY APPROACH • Gene banks, botanical gardens and using farms to raise threatened species can help prevent extinction, but these options lack funding and storage space. • Zoos and aquariums can help protect endangered animal species by preserving some individuals with the long-term goal of reintroduction, but suffer from lack of space and money.

  31. RECONCILIATION ECOLOGY • Reconciliation ecology involves finding ways to share places we dominate with other species. • Replacing monoculture grasses with native species. • Maintaining habitats for insect eating bats can keep down unwanted insects. • Reduction and elimination of pesticides to protect non-target organisms (such as vital insect pollinators).

  32. Using Reconciliation Ecology to Protect Bluebirds • Putting up bluebird boxes with holes too small for (nonnative) competitors in areas where trees have been cut down have helped reestablish populations. Figure 11-B

  33. What Can You Do? Protecting Species • Do not buy furs, ivory products, and other materials made from endangered or threatened animal species. • Do not buy wood and paper products produced by cutting remaining old-growth forests in the tropics. • Do not buy birds, snakes, turtles, tropical fish, and other animals that are taken from the wild. • Do not buy orchids, cacti, and other plants that are taken from the wild. • Spread the word. Talk to your friends and relatives about this problem and what they can do about it. Fig. 11-21, p. 246

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