1. Human activities like habitat destruction, pollution, climate change and overexploitation are greatly increasing species extinction rates.
2. Species should be protected not just for their economic value but for their intrinsic right to exist, and because biodiversity loss harms ecosystems.
3. Laws, treaties, protected areas and the precautionary principle can help prevent extinctions by protecting species and overall biodiversity.
2. Core Case Study: Polar Bears and
Global Warming
• 20,000-25,000 in the Arctic
• Most calories in winter from seals on sea ice
• Environmental impact on polar bears
• Less summer sea ice from global warming
• Could be gone from wild by 2100
• 2008: Threatened species list
4. Extinctions Are Natural but Sometimes
They Increase Sharply (1)
• Biological extinction
• No species member alive
• Background extinction
• Natural low rate of extinction
• Extinction rate
• Percentage or number of species that go extinct in a
certain time period
5. Extinctions Are Natural but Sometimes
They Increase Sharply (2)
• Mass extinction
• 3-5 events
• 50-95% of species became extinct
• From global changes in environmental conditions:
major climate change, volcanoes, asteroid impacts
• Levels of species extinction
• Local extinction
• Ecological extinction
• Biological extinction
6. Some Human Activities Are Causing
Extinctions
• Human activity has disturbed at least half of the
earth’s land surface
• Fills in wetlands
• Converts grasslands and forests to crop fields and
urban areas
• Pollution of land and water
7. Extinction Rates Are Rising Rapidly (1)
• Current extinction rate is at least 100 times higher
than typical background rate of .0001%
• Will rise to 10,000 times the background rate by the
end of the century
• Rate will rise to 1% per year
• ¼ to ½ of the world’s plant and animal species
8. Extinction Rates Are Rising Rapidly (2)
• Conservative estimates of extinction = 0.01-1.0%
• Growth of human population will increase this loss
• Rates are higher where there are more endangered
species
• Tropical forests and coral reefs, wetlands and
estuaries—sites of new species—being destroyed
9. Endangered and Threatened Species
Are Ecological Smoke Alarms (1)
• Endangered species
• So few members that the species could soon become
extinct
• Threatened species (vulnerable species)
• Still enough members to survive, but numbers
declining -- may soon be endangered
10. Endangered and Threatened Species
Are Ecological Smoke Alarms (2)
• Characteristics
• Big
• Slow
• Tasty
• Valuable parts
• Behaviors that make them easy to kill
15. Science Focus: Estimating Extinction
Rates
• Three problems
1. Hard to document due to length of time
2. Only 1.9 million species identified
3. Little known about nature and ecological roles of species
identified
• Approaches
1. Study extinction rates over last 10,000 years and then
compare with the fossil record
2. Use species–area relationship
3. Mathematical models
16. Case Study: The Passenger Pigeon:
Gone Forever
• Once one of the world’s most abundant birds
• Audubon: flock took 3 days to fly over
• Passenger pigeon hunted to extinction by 1900
• Habitat loss
• Commercial hunting
• Easy to kill: flew in large flocks and nested in dense
colonies
18. Species Are a Vital Part of the Earth’s
Natural Capital (1)
• 4 reasons to prevent extinctions
1. Species provide natural resources and natural
services
• Insects for pollination
• Birds for pest control
2. Most species contribute economic services
• Plants for food, fuel, lumber, medicine
• Ecotourism
19. Species Are a Vital Part of the Earth’s
Natural Capital (2)
3. It will take 5-10 million years to regain species
biodiversity
4. Many people believe species have an intrinsic right
to exist
23. Loss of Habitat Is the Single Greatest
Threat to Species: Remember HIPPCO
• Habitat destruction, degradation, and fragmentation
• Invasive (nonnative) species
• Population and resource use growth
• Pollution
• Climate change
• Overexploitation
24. Habitat Fragmentation
• Habitat fragmentation
• Large intact habitat divided by roads, crops, urban
development
• Leaves habitat islands
• Blocks migration routes
• Divides populations
• Inhibits migrations and colonization
• Inhibits finding food
• National parks and nature reserves as habitat islands
25. Causes of Depletion and Premature Extinction of World
Species
Fig. 9-9, p. 198
27. Some Deliberately Introduced Species
Can Disrupt Ecosystems
• Most species introductions are beneficial
• Food
• Shelter
• Medicine
• Aesthetic enjoyment
• Nonnative species may have no natural
• Predators
• Competitors
• Parasites
• Pathogens
29. Case Study: The Kudzu Vine
• Imported from Japan in the 1930s
• “ The vine that ate the South”
• Could there be benefits of kudzu?
• Fiber for making paper
• Kudzu powder reduces desire for alcohol
30. Kudzu Taking Over an Abandoned
House in Mississippi, U.S.
Fig. 9-12, p. 201
31. Some Accidentally Introduced Species
Can Also Disrupt Ecosystems
• Argentina fire ant: 1930s
• Reduced populations of native ants
• Painful stings can kill
• Pesticide spraying in 1950s and 1960s worsened
conditions
• 2009: tiny parasitic flies may help control fire ants
• Burmese python
• Florida Everglades
33. Prevention Is the Best Way to Reduce
Threats from Invasive Species
• Prevent them from becoming established
• Learn the characteristics of the species
• Set up research programs
• Try to find natural ways to control them
• International treaties
• Public education
34. What Can You Do? Controlling Invasive Species
Fig. 9-14, p. 203
35. Other Causes of Species Extinction (1)
• Human population growth
• Overconsumption
• Pollution
• Climate change
36. Other Causes of Species Extinction (2)
• Pesticides
• DDT: Banned in the U.S. in 1972
• Bioaccumulation
• Accumulates in fatty tissue of animals
• Biomagnification
• Concentration increases as you move up the food
chain
38. Illegal Killing, Capturing, and Selling of
Wild Species Threatens Biodiversity
• Poaching and smuggling of animals and plants
• Animal parts
• Pets
• Plants for landscaping and enjoyment
• Prevention: research and education
41. Individuals Matter: Pilai Poonswad
• Biologist in Thailand
• Visited poachers of rhinoceros hornbill bird and
convinced them to protect the bird instead
• Many former poachers now lead ecotourism groups
to view the birds
44. Rising Demand for Bush Meat
Threatens Some African Species
• Indigenous people sustained by bush meat
• More hunters leading to local extinction of some wild
animals
• West and Central Africa
• Helps spread HIV/AIDS and Ebola from animals to
humans
46. Case Study: A Disturbing Message
from the Birds (1)
• 1/3 of 800 bird species in U.S. are endangered or
threatened
• Habitat loss and fragmentation of the birds’ breeding
habitats
• Forests cleared for farms, lumber plantations, roads,
and development
• Intentional or accidental introduction of nonnative
species
• Eat the birds
47. Case Study: A Disturbing Message
from the Birds (2)
• Seabirds caught and drown in fishing equipment
• Migrating birds fly into power lines, communication
towers, and skyscrapers
• Other threats
• Oil spills
• Pesticides
• Herbicides
• Ingestion of toxic lead shotgun pellets
48. Case Study: A Disturbing Message
from the Birds (3)
• Greatest new threat: Climate change
• Environmental indicators
• Economic and ecological services
50. International Treaties and National Laws
Help to Protect Species
• 1975: Convention on International Trade in
Endangered Species (CITES)
• Signed by 172 countries
• Convention on Biological Diversity (BCD)
• Focuses on ecosystems and sustainability
• Ratified by 190 countries (not the U.S.)
51. Endangered Species Act
• Endangered Species Act (ESA): 1973 and later
amended in 1982, 1985, and 1988
• Identify and protect endangered species in the U.S.
and abroad
• National Marine Fisheries Service for ocean species
• U.S. Fish and Wildlife Service for all others
52. Endangered Species Act (2)
• Forbids federal agencies (except Defense) from
funding or authorizing projects that jeopardize
endangered or threatened species
• 2010: 1,370 species officially listed
• USFWS and NMFS prepare recovery plans
• Incentives for private property owners
53. Science Focus: Accomplishments of the
Endangered Species Act (1)
• Four reasons ESA not a failure for removing only 46
species from endangered list
1. Species listed only when in serious danger
2. Takes decades to help endangered species
3. Conditions for more than half of listed species are
stable or improving
4. 2010: spend only 9 cents per American
54. Science Focus: Accomplishments of the
Endangered Species Act (2)
• Three ways to improve ESA
1. Greatly increase funding
2. Develop recovery plans more quickly
3. When a species is first listed, establish the core of its
habitat that’s critical for survival
• New law needed to focus on sustaining biodiversity
and ecosystem health
56. We Can Establish Wildlife Refuges
and Other Protected Areas
• 1903: Theodore Roosevelt
• Wildlife refuges
• Most are wetland sanctuaries
• More needed for endangered plants
• Could abandoned military lands be used for wildlife
habitats?
58. Gene Banks, Botanical Gardens, and
Wildlife Farms Can Help Protect Species
• Gene or seed banks
• Preserve genetic material of endangered plants
• Botanical gardens and arboreta
• Living plants
• Farms to raise organisms for commercial sale
59. Zoos and Aquariums Can Protect
Some Species (1)
• Techniques for preserving endangered terrestrial
species
• Egg pulling
• Captive breeding
• Artificial insemination
• Embryo transfer
• Use of incubators
• Cross-fostering
60. Zoos and Aquariums Can Protect
Some Species (2)
• Goal of ultimately releasing/reintroducing
populations to the wild
• Limited space and funds
61. What Can You Do? Protecting Species
Fig. 9-22, p. 213
62. Case Study: Trying to Save the
California Condor
• Largest North American bird
• Nearly extinct
• Birds captured and breed in captivity
• By 2009, 180 in the wild
• Threatened by lead poisoning
63. The Precautionary Principle
• Precautionary principle: act to prevent or reduce
harm when preliminary evidence indicates acting is
needed
• Species: primary components of biodiversity
• Preservation of species
• Preservation of ecosystems
64. Three Big Ideas
1. We are greatly increasing the extinction of wild species by
destroying and degrading their habitats, introducing harmful
invasive species, and increasing human population growth,
pollution, climate change, and overexploitation.
2. We should avoid causing the extinction of wild species because of
the ecological and economic services they provide and because
their existence should not depend primarily on their usefulness to
us.
3. We can work to prevent the extinction of species and to protect
overall biodiversity by using laws and treaties, protecting wildlife
sanctuaries, and making greater use of the precautionary principle.
Editor's Notes
Figure 9.1: On floating ice in Svalbard, Norway, a polar bear feeds on its seal prey. Polar bears in the Arctic could become extinct sometime during this century if projected atmospheric warming melts much of the floating sea ice on which they hunt seals. Question: What do you think about the possibility that the polar bear might become extinct mostly because of human activities? Explain.
Figure 9.2: Endangered natural capital: These four critically endangered species are threatened with extinction, largely because of human activities. More than 17,300 of the world’s species, including 1,318 species in the United States, were officially listed in 2009 as endangered or threatened species. The number below each photo indicates the estimated total number of individuals of that species remaining in the wild. These and thousands of other species may disappear forever during your lifetime. According to most biologists, the actual number of species at risk is much larger. Question: What kinds of human activities to you think are putting these four animals in danger? (a) Sumatran tiger: less than 60 in Sumatra, Indonesia
Figure 9.2: Endangered natural capital: These four critically endangered species are threatened with extinction, largely because of human activities. More than 17,300 of the world’s species, including 1,318 species in the United States, were officially listed in 2009 as endangered or threatened species. The number below each photo indicates the estimated total number of individuals of that species remaining in the wild. These and thousands of other species may disappear forever during your lifetime. According to most biologists, the actual number of species at risk is much larger. Question: What kinds of human activities to you think are putting these four animals in danger? (a) Sumatran tiger: less than 60 in Sumatra, Indonesia
Figure 9.3: This diagram shows the characteristics of species that can put them in greater danger of becoming extinct. Question: Which of these characteristics might possibly contribute to the extinction of the polar bear ( Core Case study ) during this century?
Figure 9.4: E ndangered natural capital. This graph shows the estimated percentages of various types of known species that are threatened with extinction because of human activities ( Concept 9-1 ). Question: Why do you think plants (see Photo 4 in the Detailed Contents) and fish species top this list? (Data from International Union for Conservation of Nature, Conservation 2009)
Figure 9.5: Because of human activities, the North American passenger pigeon became extinct in the wild in 1900. In 1914, the world’s last known passenger pigeon died in a zoo in the U.S. city of Cincinnati, Ohio .
Figure 9.6: N atural capital degradation. These endangered orangutans are shown in their rapidly disappearing tropical forest habitat. In 1900, there were over 315,000 wild orangutans, which are found only in the tropical forests of Indonesia and Malaysia. According to the WWF, today there are fewer than 56,000 left in the wild (90% of them in Indonesia). These highly intelligent animals are disappearing at a rate of more than 1,000–2,000 per year because of illegal smuggling and the clearing of their tropical forest habitat to make way for plantations that supply palm oil used in cosmetics, cooking, and the production of biodiesel fuel. An illegally smuggled, live orangutan sells for a street price of up to $10,000. Without urgent protective action, the endangered orangutan may be the first great ape species to become extinct, primarily because of human activities. Question: What difference will it make if human activities cause the extinction of the orangutan?
Figure 9.7: N atural capital. These plant species are examples of nature’s pharmacy. Their scientific names (see Supplement 5, p. S18–S19) and some of their medicinal uses are shown as well. Parts of these plants as well as a number of other plant and animal species (many of them found in tropical forests) are used to treat a variety of human ailments and diseases. Once the active ingredients in the plants have been identified, scientists can usually produce them synthetically. The active ingredients in nine of the ten leading prescription drugs originally came from wild organisms. Many of the world’s tropical plant species are likely to become extinct before we can even study them. Question: Which of these species, if any, might have helped you or people you know to deal with health problems?
Figure 9.8: Many species of wildlife such as this endangered hyacinth macaw are sources of beauty and pleasure. This species of parrot is found in fairly open woodlands and swamps in several areas of Brazil, Bolivia, and Paraguay. This and other colorful species of parrots have become endangered because many birds have been removed from the wild and sold (sometimes illegally) as pets.
Figure 9.9: This figure illustrates both the underlying and direct causes of depletion and extinction of wild species resulting from human activities ( Concept 9-3 ) (see Figure 1-9, p. 13). The biggest cause is habitat loss, degradation, and fragmentation. This is followed by the deliberate or accidental introduction of harmful invasive (nonnative) species into ecosystems. Question: What are two direct causes that are specifically related to each of the underlying causes?
Figure 9.10: N atural capital degradation. These maps reveal the reductions in the ranges of four wildlife species, mostly as the result of severe habitat loss and fragmentation and illegal hunting for some of their valuable body parts. What will happen to these and millions of other species during the next few decades when the human population grows by at least 2 billion—the equivalent of more than 6 times the current U.S. population and almost twice the current population of China—as is projected by scientists? See an animation based on this figure at CengageNOW. Question: Would you support expanding these ranges even though this would reduce the land available for human habitation and farming? Explain. (Data from International Union for the Conservation of Nature and World Wildlife Fund )
Figure 9.11: These are some of the more than 7,100 harmful invasive (nonnative) species that have been deliberately or accidentally introduced into the United States.
Figure 9.12: Kudzu has taken over this abandoned house in the U.S. state of Mississippi. The vine, which can grow 5 centimeters (2 inches) per hour, was deliberately introduced into the United States for erosion control. Digging it up and burning it do not halt its spread. Grazing goats and repeated doses of herbicides can destroy it, but goats and herbicides also destroy other plants, and herbicides can contaminate water supplies. Scientists have found a common fungus that can kill kudzu within a few hours, apparently without harming other plants, but they need to investigate any harmful side effects it may have .
Figure 9.13: This huge python and an American alligator were in a life-or-death struggle in the Florida Everglades. After a 10-hour battle the alligator killed the snake by taking it underwater and drowning it. However, in some struggles, these snakes kill and eat the alligators—their only natural predator in the Everglades.
Figure 9.14: I ndividuals matter. Here is a list of some ways to prevent or slow the spread of harmful invasive species. Questions: Which two of these actions do you think are the most important? Why? Which of these actions do you plan to take?
Figure 9.15: Bioaccumulation and biomagnification: DDT is a fat-soluble chemical that can accumulate in the fatty tissues of animals. In a food chain or web, the accumulated DDT is biologically magnified in the bodies of animals at each higher trophic level. (Dots in this figure represent DDT.) The concentration of DDT in the fatty tissues of organisms was biomagnified about 10 million times in this food chain in an estuary near Long Island Sound in the U.S. state of New York. If each phytoplankton organism takes up and retains one unit of DDT, a small fish eating thousands of zooplankton (which feed on the phytoplankton) will store thousands of units of DDT in its fatty tissue. Each large fish that eats ten of the smaller fish will ingest and store tens of thousands of units, and each bird (or human) that eats several large fish will ingest hundreds of thousands of units. Question: How does this story demonstrate the value of pollution prevention ?
Figure 9.16: This male mountain gorilla inhabits the bush of the African country of Rwanda. Mountain gorillas feed mostly on the leaves, shoots, and stems of a variety of plants. Only about 700 individuals of this critically endangered species remain in the wild.
Figure 9.17: This white rhinoceros was killed by a poacher in South Africa solely for its horns. Question: What would you say if you could talk to the person who killed this animal?
Figure 9.A: Professor Pilai Poonswad, a biologist at Mahidol University in Thailand, decided to confront poachers who were a threat to the rare rhinoceros hornbill.
Figure 9.B: The rare Rhinoceros hornbill is found in tropical and subtropical forest habitats in parts of Asia. It emits a loud honking squawk and uses its long bill to defend itself from predators such as snakes and monkeys. Its habitat is threatened by agricultural development and logging, and in some areas, the hornbill is threatened by local tribesmen who kill it for food and for its feathers. It is also captured and sold live as part of the illegal wildlife trade.
Figure 9.18: Bush meat such as this severed head of an endangered lowland gorilla in the Congo is consumed as a source of protein by local people in parts of West and Central Africa and is sold in national and international marketplaces. You can find bush meat on the menu in Cameroon and the Democratic Republic of the Congo in West Africa as well as in Paris, London, Toronto, New York, and Washington, DC. Poachers are often the suppliers of bush meat. Wealthy patrons of some restaurants regard gorilla meat as a source of status and power. Question: How, if at all, is this different from killing a cow for food?
Figure 9.19: The IUCN reports that 82% of albatrosses are threatened. The black-browed albatross shown here is endangered because of a drastic reduction in its population, due largely to long-line and trawler fishing fleets whose hooks and nets ensnare and drown these birds when they dive into the water for food.
Figure 9.20: These confiscated products were made from endangered species. Because of a scarcity of funds and inspectors, probably no more than one-tenth of the illegal wildlife trade in the United States is discovered. The situation is even worse in most other countries.
Figure 9.21: The Pelican Island National Wildlife Refuge in Florida was America’s first National Wildlife Refuge. It was established in 1903 to help protect the brown pelican (see photo insert) and other birds from extinction. In 2009, the brown pelican was removed from the U.S. endangered species list .
Figure 9.22: I ndividuals matter. You can help prevent the extinction of species. Questions: Which two of these actions do you believe are the most important? Why?
