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Sustaining Biodiversity

Sustaining Biodiversity. The Species Approach. 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

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Sustaining Biodiversity

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  1. Sustaining Biodiversity The Species Approach

  2. 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

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

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

  5. Narrow Distribution • Many Island species are endemic (found no where else in the world) • Habitat island – any habitat surrounded by another • National parks, natural reserves, fresh water lakes • Theory of Island Biogeography • Size • Proximity to mainland

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

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

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

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

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

  11. Habitat Fragmentation Roads Logging agriculture Sometimes creates barriers to migration

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

  13. 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

  14. For the Birds • 75%of threatened birds are in tropical forest • Millions of birds collide with man-made structures built along migratory paths • India • 95% drop in Gyp Vulture population • Rise in ferel dogs and cats • Rise in number of cases of rabies

  15. Indicator Species Birds live in every climate Respond quickly to environmental change Relatively easy to track and count

  16. 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

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

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

  19. 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

  20. 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

  21. 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

  22. 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.

  23. 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

  24. 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

  25. 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.

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

  27. 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

  28. 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.

  29. 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.

  30. 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

  31. 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

  32. 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

  33. 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.

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