Download Ch. 9 Sustaining Biodiversity The Species Approach Notes

4/16/13
Sustaining
Biodiversity:
The Species
Approach
Notes
Passenger Pigeon - Gone Forever
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.
Chapter 9
Endangered and Threatened
Species: Ecological Smoke Alarms
Global Extinction
•  Some animals have become prematurely
extinct because of human activities.
•  Endangered species: so few individual
survivors that it could soon become extinct.
•  Threatened species: still abundant in its
natural range but is likely to become
endangered in the near future.
SPECIES
EXTINCTION
•  Some species
have
characteristics
that make them
vulnerable to
ecological and
biological
extinction.
Fig. 11-3, p. 224
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SPECIES EXTINCTION
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.
–  The 2004 Red List contains 15,589 species at
risk for extinction.
SPECIES EXTINCTION
•  Scientists use
models to
estimate the risk
of particular
species becoming
extinct or
endangered.
HABITAT LOSS, DEGRADATION,
AND FRAGMENTATION
•  Percentage of various species types
threatened with premature extinction from
human activities.
IMPORTANCE OF WILD
SPECIES
•  We should not cause the premature
extinction of species because of the
economic and ecological services they
provide.
•  Some believe that each wild species has an
inherent right to exist.
–  Some people distinguish between the survival
rights among various types of species (plants vs.
animals).
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
•  The greatest threat to a species is the loss,
degradation, and fragmentation of where it lives.
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HABITAT LOSS, DEGRADATION,
AND FRAGMENTATION
•  Reduction in
ranges of four
wildlife species,
mostly due to
habitat loss
and
overharvest.
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.
INVASIVE SPECIES
•  Many invasive species have been
introduced intentionally.
Fig. 11-11, p. 234
INVASIVE SPECIES
•  The Argentina fire
ant was
introduced to
Mobile, Alabama
in 1932 from
South America.
–  Most probably
from ships.
–  No natural
predators.
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.
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Characteristics of
Successful
Invader Species
Characteristics of
Ecosystems Vulnerable
to Invader Species
• High reproductive rate,
short generation time
(r-selected species)
• Climate similar to
habitat of invader
• Absence of predators
on invading species
• Pioneer species
• Long lived
• Early successional
systems
• High dispersal rate
• Release growth-inhibiting
chemicals into soil
• Low diversity of
native species
• Absence of fire
• Generalists
• High genetic variability
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.
• Disturbed by human
activities
Pollution
OVEREXPLOITATION
•  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.
OVEREXPLOITATION
•  Rhinoceros are
often killed for their
horns and sold
illegally on the
black market for
decorative and
medicinal
purposes.
•  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.
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.
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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.
The U.S. Endangered Species Act
•  Biodiversity hotspots in relation to the largest
concentrations of rare and potentially
endangered species in the U.S.
Endangered Species
•  Congress has amended the ESA to help
landowners protect species on their land.
•  Some believe that the ESA should be
weakened or repealed while others believe
it should be strengthened and modified to
focus on protecting ecosystems.
•  Many scientists believe that we should
focus on protecting and sustaining
biodiversity and ecosystem function as the
best way to protect species.
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.
Endangered Species
•  Because of
scarcity of
inspectors,
probably no
more than
1/10th of the
illegal wildlife
trade in the
U.S. is
discovered.
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.
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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.
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).
Using Reconciliation Ecology to
Protect Bluebirds
•  Putting up bluebird
boxes with holes
too small for
(nonnative)
competitors in
areas where trees
have been cut
down have helped
reestablish
populations.
Fig. 9-22, p. 213
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