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Sustaining Biodiversity:
The Species Approach
Chapter 9
9-1 What Role Do Humans Play in the
Premature Extinction of Species?
 Concept 9-1A We are degrading and
destroying biodiversity in many parts of the
world, and these threats are increasing.
 Concept 9-1B Species are becoming extinct
100 to 1,000 times faster than they were before
modern humans arrived on the earth (the
background rate), and by the end of this century,
the extinction rate is expected to be 10,000
times the background rate.
Human Activities Are Destroying and
Degrading Biodiversity
 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
 Degraded aquatic biodiversity
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.
Some Human Activities Cause Premature
Extinctions; the Pace Is Speeding Up
 Conservative estimates of extinction = 0.011.0%
• 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
HABITAT LOSS, DEGRADATION, AND
FRAGMENTATION
Figure 9-10
 The greatest threat to a species is the loss,
degradation, and fragmentation of where it lives.
Number of
species
existing
Effects of a 0.1% extinction rate
5 million
5,000 extinct per year
14 million
50 million
100 million
0
14,000 extinct per year
50,000 extinct per year
100,000 extinct per year
50
100
150
Number of years until one million
species are extinct
200
Fig. 9-3, p. 186
Endangered Natural Capital: Species
Threatened with Premature Extinction
Fig 9-4
Characteristic
Examples
Low reproductive
rate (K-strategist)
Blue whale, giant
panda, rhinoceros
Specialized
niche
Narrow
distribution
Blue whale, giant
panda, Everglades
kite
Elephant seal,
desert pupfish
Feeds at high
trophic level
Bengal tiger, bald
eagle, grizzly bear
Fixed
migratory
patterns
Rare
Commercially
valuable
Large territories
Blue whale,
whooping crane,
sea turtle
African violet,
some orchids
Snow leopard, tiger,
elephant, rhinoceros,
rare plants and birds
California condor,
grizzly bear, Florida
panther
Stepped Art
Fig. 9-5, p. 188
Percentage of Various Species
Threatened with Premature Extinction
Fig 9-6
Science Focus: Estimating Extinction
Rates Is Not Easy
 Three problems
• Hard to document due to length of time
• Only 1.8 million species identified
• Little known about nature and ecological roles of
species identified
9-2 Why Should We Care about Preventing
Premature Species Extinction?
 Concept 9-2 We should prevent the premature
extinction of wild species because of the
economic and ecological services they provide
and because they have a right to exist
regardless of their usefulness to us.
Why Should We Care About Biodiversity?
•
•
•
•
•
•
•
•
•
Aesthetic pleasure
Ecological: (environmental monitor, ecological balance –
keystone species)
Educational
Historical or cultural
Natural Services: (air and water purification, soil fertility,
waste disposal,)
Recreational
Medicine
Agriculture: (biological pest control, food source,
commercial product – wood)
Moral or ethics
Natural Capital: Nature’s Pharmacy
Fig 9-8
Endangered Scarlet Macaw is a Source
of Beauty and Pleasure
9-3 How do Humans Accelerate
Species Extinction?
 Concept 9-3 The greatest threats to any
species are (in order) loss or degradation of its
habitat, harmful invasive species, human
population growth, pollution, climate change,
and overexploitation.
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
NATURAL CAPITAL
DEGRADATION
Causes of Depletion and Premature Extinction of Wild Species
Underlying Causes
• Population growth
• Rising resource use
• Undervaluing natural capital
• Poverty
Direct Causes
• Habitat loss
• Pollution
• Commercial hunting and poaching
• Habitat degradation and
fragmentation
• Introduction of nonnative
species
• Climate change
• Sale of exotic pets and decorative
plants
• Overfishing
• Predator and pest control
Fig. 9-10, p. 193
Animation: Humans affect
biodiversity
Click for animation
Natural Capital Degradation: Reduction
in the Ranges of Four Wildlife Species
Fig 9-11
Case Study: A Disturbing Message
from the Birds (1)
 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
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
Distribution of Bird Species in North
America and Latin America
Fig 9-12
The Ten Most Threatened Song Birds
in the United States
Fig 9-13
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
Fig. 9-14a, p. 199
Fig. 9-14b, p. 199
Argentina Fire Ant Accidentally
Introduced into Mobile, Alabama, U.S.
Fig 9-11
Quagga and Zebra
Mussels in California
Quagga fact sheet
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.
Arundo removal in the Santa
Clara River Watershed
Click for Aurndo report
Negative Impacts of Arundo
• Reduction in the shading of surface water, resulting in increased water
temperatures and decreased dissolved-oxygen content, which has a negative
impact on native wildlife
• Reduction in groundwater availability through rapid transpiration
• Alterations in channel morphology by retaining sediments and constricting
flows
• Increased bank erosion due to the diversion of water around established
stands
• Displacement of riparian habitat through monopolization of soil moisture
• Displacement of riparian habitat due to establishment dense monocultures of
arundo
• Reduction in the food supply (particularly insects) of riparian-dependent
wildlife
• Reduction of wildlife utilization of an infested area
• Increased probability of wildfire occurrences, intensity, and area from
increased fire fuel loads
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
Characteristics of Invader Species and
Ecosystems Vulnerable to Invading Species
Fig 9-17
What Can You Do? Controlling
Invasive Species
Fig 9-18
Bioaccumulation and Biomagnification
Fig 9-19
Confiscated Products Made
from Endangered Species
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
9-4 How Can We Protect Wild Species
from Premature Extinction? (1)
 Concept 9-4A We can use existing
environmental laws and treaties and work to
enact new laws designed to prevent species
extinction and protect overall biodiversity.
 Concept 9-4B We can help to prevent species
extinction by creating and maintaining wildlife
refuges, gene banks, botanical gardens, zoos,
and aquariums.
9-4 How Can We Protect Wild Species
from Premature Extinction? (2)
 Concept 9-4C According to the precautionary
principle, we should take measures to prevent
or reduce harm to the environment and to
human health, even if some of the cause-andeffect relationships have not been fully
established, scientifically.
International Treaties Help to
Protect Species
 1975: Convention on International Trade in
Endangered Species (CITES)
• Signed by 172 countries
Click for link to CITES
 Convention on Biological Diversity (BCD)
• Focuses on ecosystems
• Ratified by 190 countries (not the U.S.)
Click for link to BCD
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.
• There are now 47,667 species on the IUCN Red List (2009
data) and 17,291 of them are threatened with extinction,
up from 16,118 last year.
IUCN web page
Figure 11-5
Case Study: The U.S. Endangered
Species Act (1)
 Endangered Species Act (ESA): 1973 and later
amended in 1982, 1983, and 1985
 Identify and protect endangered species in the
U.S. and abroad
 Hot Spots
Case Study:
The U.S. Endangered Species Act
Fig 10-27
 Biodiversity hotspots in relation to the largest
concentrations of rare and potentially endangered
species in the U.S.
Science Focus: Accomplishments
of the Endangered Species Act (1)
 Species listed only when serious danger of
extinction
 Takes decades for most species to become
endangered or extinct
 More than half of the species listed are stable or
improving
 Budget has been small
Science Focus: Accomplishments
of the Endangered Species Act (2)
 Suggested changes to ESA
• Increase the budget
• Develop recovery plans more quickly
• Establish a core of the endangered organism’s
survival habitat
Click for US Fish and Wildlife Service
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.
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?
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
Zoos and Aquariums Can Protect
Some Species (1)
 Techniques for preserving endangered
terrestrial species
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•
•
•
•
•
Egg pulling
Captive breeding
Artificial insemination
Embryo transfer
Use of incubators
Cross-fostering
Zoos and Aquariums Can Protect
Some Species (2)
 Limited space and funds
 Critics say these facilities are prisons for the
organisms
What Can You Do? Protecting Species
Fig 9-24
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).
The Precautionary Principle
 Species: primary components of biodiversity
 Preservation of species
 Preservation of ecosystems
Animation: Humans affect biodiversity
Click for animation