Transcript Endangered species

Value of wild species & biodiversity
• Ecosystem capital: goods & services provided to
humans by natural systems
• ecosystem capital = ecosystems
• ecosystems = wild species
• Ecosystem sustainability = save ecosystem
integrity, resilience, processes, biodiversity
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Biological wealth
• 2 million species examined, named, classified
• 5–30 million species
• Biota: natural species of living things
• Biological wealth: biota + their ecosystems
• = ecosystem capital & sustains humans
• major part of a country’s total wealth
• Biodiversity: variety of living species
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Biodiversity Value
• Why shouldn’t we hunt species to extinction?
• Wild species have value & essential to preserve
• By identifying this value we can assess our moral
duties to species
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• Instrumental value: a species’ existence benefits
some other organism
• Food, shelter, source of income
• Usually anthropocentric
• preserve species = enjoy benefits provided
• Intrinsic value: value for own sake
• not have to be useful to us
• Do animals have rights? Or are they simply property?
• Many believe only humans have intrinsic value
• no reason to preserve “insignificant” species
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Recreational, aesthetic, and scientific
uses
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• Ecotourism: tourists visit a place to observe wild
species or unique ecological sites
• It is the largest foreign exchange-generating
enterprise for many developing countries
• Environmental degradation affects commercial
interests
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Biodiversity & its decline
• Biodiversity = genetic diversity too
• Species #
• How “even” the species are
• ↓biodiversity if dominated by 1 species with few
other species
• ↑biodiversity if dominance of any 1 species ↓
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• Endemic species- found in 1 habitat
• at risk
• North America still not well-known
• At least 500 species (100 vertebrates) extinct
• 1/3 species are vulnerable or extinct
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North America
• Freshwater habitats ↑ risk
• Ex: Mussels, crayfish, fishes, amphibians
• American SE ↑ freshwater diversity
• Declining
• Fish, amphibians, songbirds
• More than 25% of North American birds are
declining
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The state of U.S. species
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Global outlook
• The global loss of biodiversity is disturbing
• The background (past) extinction rate is less than
one extinction every thousand years for mammals
• Except for the five great extinction events
• Current extinction rate = 100–1,000 times greater
than past rates
• For mammals and birds = 20–25 species per 100
years
• Rates for all groups = 850 species over 500 years
• 23% of mammal species and 12% of bird species
are threatened
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Species extinction rates
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Most threatened species are in the
tropics
• The tropics have almost unimaginable biodiversity
• 43 species of ants occur on one tree in Peru
• Equal to all ant fauna of the British Isles
• 300 species of trees on a 1-ha (2.5-acre) plot
• 1,000 species of beetles on one tree species in
Panama
• Tropical forests are also experiencing the highest
rate of deforestation
• The species inventory is so incomplete it’s almost
impossible to assess extinction rates
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Reasons for the decline
• HIPPO
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Habitat destruction
Invasive species
Pollution
Population
Overexploitation
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Biodiversity loss in the developing
world
• developing world
• Biodiversity is greatest
• So is human population growth
• Asia & Africa have lost two-thirds of their original
natural habitat
• People’s desire for a better life
• Desperate poverty
• Global market for timber and other resources
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The border of Haiti and the Dominican
Republic
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Habitat change: fragmentation
• mosaic of different land uses
• contrast with neighboring patches
• Fragmentation small # & species
populations
• Species vulnerable to extinction
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Fragmentation
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Fragmentation: edge
• Reducing habitat size increases edge
• Exposing species to predators and nest parasites
• Edge is beneficial to some species but not to
others
• Kirtland’s warbler, an endangered species,
depends on jack pines in Michigan
• Forests have been fragmented, creating edge
• Brown-headed cowbirds are nest parasites that lay
their eggs in the warbler’s nest
• Edge also favors nest predators (crows, magpies,
jays)
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Habitat change: simplification and
intrusion
• Simplification: humans simplify habitats
• Removing logs and trees changes forest
microhabitats
• Streams are channelized (straightened), reducing
fish and invertebrate species
• Intrusion: human structures
• Millions of migrating birds crash into
telecommunication towers
• Cell phone tower lights affect birds migrating at night
• Up to a billion birds die each year by crashing into
windows
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Invasive species
• An exotic (alien) species: one that is introduced into
an area from somewhere else
• Most don’t survive or don’t become pests
• Invasive species: thrives, spreads, and can eliminate
native species by predation or competition
• Accidental introductions: the brown tree snake
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Entered Guam on cargo ships
Within 50 years, it eliminated 9 of 12 bird species
It has no natural enemies
Wildlife officials are trying to prevent its spread
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The brown tree snake
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• Aquaculture: the farming of shellfish, seaweed,
and fish
• Introducing parasites, seaweeds, invertebrates,
pathogens
• Species escape and enter nearby waterways
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The Brazilian pepper bush
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Invasive species and trophic levels
• Nonnative plants have different resistance
mechanisms
• Make it harder for herbivores to eat
• Energy and materials may not pass up the food
chain
• Norway maples were introduced to North
America in 1756
• They provide less food up the food chain for
herbivores (caterpillars) and their predators (song
birds)
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Population
• Human populations put pressure on species
• Direct use, habitat conversion, pollution
• Large numbers of humans use resources wild
species need
• Even if each person uses small amounts of
resources
• A small group of people can overuse resources
• People with highly consumptive resources have a
disproportionate effect on the environment
• Different levels of consumption and numbers of
people drive tensions between countries
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Overexploitation: trade in exotics
• Overexploitation: overharvest of a particular
species
• Removing individuals faster than they can
reproduce
• Overuse of species harms ecosystems
• Driven by greed, ignorance, desperation, poor
management
• Overcutting forests, overgrazing, overhunting, etc.
• Trade in exotics: much trade is illegal
• Illegal trade generates $12 billion/yr, the third
largest source after drugs and guns
• Consumers pay huge prices for “luxuries” (e.g.,
polar bear rugs)
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Consequences of losing biodiversity
• Biodiversity is essential for ecosystem goods and
services
• Mangroves and coral reefs buffer against storms
• Ecotourism depends on biodiversity
• Energy flow and nutrient cycling are driven by
species
• Keystone species: species whose role is vital to
survival of other species
• Predators control herbivores
• Umbrella species: larger animals that need
unspoiled habitat (wolves, elephants, tigers,
moose, etc.)
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Highway overpasses
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Cougar on the roof
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Endangered Species Act (1973)
• Endangered species: in imminent danger of
becoming extinct if it is not protected
• Includes genetically distinct subpopulations
(subspecies)
• Threatened species: in jeopardy but not yet
endangered
• An officially recognized endangered or threatened
species
• Fines are levied for killing, trapping, uprooting
(plants), or engaging in commerce
• Administered by the U.S. Fish and Wildlife Service
and the National Oceanic and Atmospheric
Administration Fisheries Service
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Endangered species
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Elements of the Endangered Species
Act
• Listing: by the appropriate agency, individuals,
groups, state agencies
• Based on the best available information
• Does not include any economic impact of listing
• Critical habitat: areas where a species is or could
spread as it recovers
• Includes privately held lands
• Recovery plans: designed to allow listed species
to survive and thrive
• Developed by the appropriate agency
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The American bald eagle
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The Red List
• Maintained by the IUCN for threatened species
• Evaluates the risk of extinction for thousands of
species
• Frequently updated and available on the Internet
• In 2008, it had 16,928 species
• Each species is classified
• Given its distribution, documentation, habitat,
ecology, conservation measures, and data
sources
• Not actively engaged in preserving species
• It is the basis of conservation activities
• Provides crucial leadership
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Critical ecosystem partnership fund
• Sponsored by multiple entities and foundations
• Provides grants to NGOs and community-based
groups for conservation activities in biodiversity
“hot spots”
• Hot spots are 34 regions making up 2.3% of Earth’s
land surface
• Contain 75% of the most threatened species
• By 2008, the fund had provided $102 million
• 1,300 partners to work on preserving biodiversity in
these hot spots
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Biodiversity hot spots
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