Download Human Activities Cause Premature Extinctions

Sustaining Biodiversity:
The Species Approach
Chapter 9
Core Case Study: The Passenger
Pigeon: Gone Forever
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Passenger pigeon hunted to extinction by 1900
Commercial hunters used a "stool pigeon”
Archeological record shows five mass extinctions
Human activities: hastening more extinctions?
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 to
83%* of the earth’s land surface
– Filling in wetlands
– Converting grasslands and forests to crop fields
and urban areas
• Degraded aquatic biodiversity
*2005 Millennium Ecosystem Assessment
Extinctions Are Natural but
Sometimes They Increase Sharply
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Background extinction estimated = 0.0001%
Extinction rate Can be #/million/year or %/yr.
Mass extinction: causes?
Levels of species extinction
– Local extinction – extinct in one area, but not others
– Ecological extinction – so few individuals that species
can’t fill their ecological role
– Biological extinction – none anywhere on earth… this is
forever.
Human Activities Cause Premature
Extinctions: Pace Is Speeding Up
• Premature extinctions due to
– Habitat destruction
– Overhunting
• Where are the golden toads?
Human Activities Cause Premature
Extinctions: Pace Is Speeding Up
• Conservative estimates of extinction = 0.01-1%
– 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
• Speciation crisis – “death is one thing. The
lack of births is another.” (loss of genetic
biodiversity and diverse habitats can cause
speciation to slow)
Effects of a 0.1% Extinction Rate
Endangered and Threatened Species
Are Ecological Smoke Alarms
• Endangered species – so few indiv. left that it
could soon become extinct over all or part of
natural range.
• Threatened species (vulnerable species) –
likely to become endangered soon… declining
numbers
Endangered
Natural
Capital:
Species
Threatened
with
Premature
Extinction
Characteristics
of Species That
Are Prone to
Ecological and
Biological
Extinction
Percentage of Various Species
Threatened with Premature
Extinction
IUCN
• International Union for the Conservation of
Nature and Natural Resources – World
Conservation Union
• Red lists – in 2007: 16,306 species of plant and
animals listed as in danger of extinction.
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
• Document little changes in DNA
• Use species–area relationship - 90% habitat
loss causes 50% of species to become extinct
• Mathematical models
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.
Species Are a Vital Part of the
Earth’s Natural Capital
• Instrumental value (2 forms)
– 1) Use value
• Ecotourism: wildlife tourism
• Genetic information
– 2) Nonuse value
• Existence value – appreciate that it exists
• Aesthetic value – it’s pretty
• Bequest value – willing to pay so it will be there for
future generations
• Ecological value – plays a role in ecosystem
Natural Capital Degradation:
Endangered Orangutans in Tropical
Forest
Natural Capital: Nature’s
Pharmacy
Science Focus: Using DNA to Reduce
Illegal Killing of Elephants for Their
Ivory
• 1989 international treaty against poaching
elephants (although, poaching is on the rise)
• Track area of poaching through DNA analysis
of elephants
• WWF - Wildlife crime scorecard
• Elephants damaging areas
of South Africa: Should
they be culled?
Are We Ethically Obligated to
Prevent Premature Extinction?
• Intrinsic value: existence value
• Edward O. Wilson: biophilia phenomenon
• Biophobia
Science Focus: Why Should We
Care about Bats?
• Vulnerable to extinction
– Slow to reproduce
– Human destruction of habitats
• Important ecological roles
– Feed on crop-damaging nocturnal insects
– Pollen-eaters
– Fruit-eaters
• Unwarranted fears of bats
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
Causes of Depletion and
Premature Extinction of World
Species
Natural
Capital
Degradation:
Reduction in
the Ranges of
Four Wildlife
Species
Science Focus: Studying the Effects
of Forest Fragmentation on OldGrowth Trees
• Tropical Biologist Bill Laurance, et al.
• How large must a forest fragment be in order to
prevent the loss of rare trees?
• Within 100m of the edge of plots, 36% of old-growth
biomass is lost.
Case Study: A Disturbing Message
from the Birds
• 70% of species declining
• 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
– Everglades!
Case Study: A Disturbing Message
from the Birds
• Seabirds caught and drown in fishing equipment
• Migrating birds fly into power lines, communication
towers, and skyscrapers
• Other threats
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Oil spills
Pesticides
Herbicides
Ingestion of toxic
lead shotgun
pellets
Case Study: A Disturbing Message
from the Birds
• Greatest new threat: Climate change
• Environmental indicators
• Economic and ecological services
Distribution
of Bird
Species in
North
America and
Latin
America
The 10 Most Threatened Song Birds
in the United States
Science Focus: Vultures, Wild Dogs,
and Rabies: Unexpected Scientific
Connections
• Vultures poisoned from diclofenac in cow
carcasses
• More wild dogs eating the cow carcasses
(increases milk production in cows)
• Increase in wild dog population
• More rabies spreading to people – more than
½ of rabies cases in the world
Some Deliberately Introduced
Species Can Disrupt Ecosystems
• Most species introductions are beneficial
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Food
Shelter
Medicine
Aesthetic enjoyment
• Nonnative species may have no natural
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Predators
Competitors
Parasites
Pathogens
Case Study: The Kudzu Vine
• Imported from Japan in the 1930s
• “ The vine that ate the South”
• Could there be benefits of kudzu?
Some Accidentally Introduced
Species Can Also Disrupt
Ecosystems
• Argentina fire ant: 1930s
– Pesticide spraying in 1950s and 1960s worsened
conditions
• Burmese python
Argentina
Fire Ant
Accidentally
Introduced
into Mobile,
Alabama,
U.S.
Prevention Is the Best Way to Reduce
Threats from Invasive Species
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Prevent them from becoming established
Learn the characteristics of the species
Set up research programs
Try to find natural ways to control them
Other Causes of Species Extinction
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Population growth
Overconsumption
Pollution
Climate change
Other Causes of Species Extinction
• Pesticides
– DDT: Banned in the U.S. in 1972
• Bioaccumulation- increase in concentration
of a pollutant from the environment to the
first organism in a food chain
• Biomagnification-increase in concentration
of a pollutant from one link in a food chain to
another
Bioaccumulation and
Biomagnification
Case Study: Where Have All the
Honeybees Gone?
• Honeybees responsible for 80% of insectpollinated plants
• Dying due to?
– Pesticides
– Parasites
– Bee colony collapse syndrome
Case Study: Polar Bears and
Global Warming
• Environmental impact on polar bears
– Less summer sea ice
– PCBs and DDT
• 2007: Threatened species list
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
Animals Killed by a Poacher
Individuals Matter: Jane Goodall
• Primatologist and anthropologist
• 45 years understanding and protecting
chimpanzees
– Chimps have tool-making skills
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
9-4 How Can We Protect Wild Species
from Premature Extinction?
• 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.
• 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 causeand-effect 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
• Convention on Biological Diversity (BCD)
– Focuses on ecosystems
– Ratified by 190 countries (not the U.S.)
Case Study: The U.S.
Endangered Species Act
• 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
• Habitat Conservation Plan (HCP) colony
Case Study: The U.S.
Endangered Species Act
• Mixed reviews of the ESA
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Weaken it
Repeal it
Modify it
Strengthen it
Simplify it
Streamline it
Confiscated Products Made from
Endangered Species
Science Focus: Accomplishments
of the Endangered Species Act
• 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
• Suggested changes to ESA
– Increase the budget
– Develop recovery plans more quickly
– Establish a core of the endangered organism’s
survival habitat
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? (UXO at Big Oaks in
Southeastern Indiana)
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
• 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
• Limited space and funds
• Critics say these facilities are prisons for the
organisms
Case Study: Trying to Save the
California Condor
• Largest North American bird
• Nearly extinct
– Birds captured and breed in captivity
• By 2007, 135 released into the wild
– Threatened by lead poisoning
The Precautionary Principle
• Species: primary components of biodiversity
• Preservation of species
• Preservation of ecosystems