Chapter 9 - Plainfield North High Schoolpnhs.psd202.org/documents/zgonzale/1510764500.pdf ·...
Transcript of Chapter 9 - Plainfield North High Schoolpnhs.psd202.org/documents/zgonzale/1510764500.pdf ·...
Core Case Study:
The Passenger Pigeon - Gone
Forever Once the most
numerous bird on earth.
In 1858, Passenger
Pigeon hunting became
a big business.
By 1900 they became
extinct from over-
harvest and habitat
loss.
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.
Endangered and Threatened
Species: Ecological Smoke Alarms
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
Scientists use
models to
estimate the risk
of particular
species becoming
extinct or
endangered.
HABITAT LOSS, DEGRADATION,
AND FRAGMENTATION
Conservation biologists summarize the most
important causes of premature extinction as
“HIPPCO”:
Habitat destruction, degradation, and
fragmentation
Invasive species
Population growth
Pollution
Climate change
Overharvest
HABITAT LOSS, DEGRADATION,
AND FRAGMENTATION
Reduction in
ranges of four
wildlife species,
mostly due to
habitat loss
and
overharvest.
Case Study:
A Disturbing Message from the Birds
Human activities are causing serious declines
in the populations of many bird species.
Case Study:
A Disturbing Message from the Birds
The majority of the
world’s bird species are
found in South
America.
Threatened with habitat
loss and invasive
species.
INVASIVE SPECIES
Many nonnative
species provide us
with food, medicine,
and other benefits.
Some can wipe out
native species,
disrupt ecosystems,
and cause large
economic losses.
Kudzu vine was introduced in the southeastern U.S. to control erosion. It has taken over native species habitats.
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.
• Climate similar to
habitat of invader
• Absence of predators
on invading species
• Early successional
systems
• Low diversity of
native species
• Absence of fire
• Disturbed by human
activities
Characteristics of
Successful
Invader Species
• High reproductive rate,
short generation time
(r-selected species)
• Pioneer species
• Long lived
• High dispersal rate
• Release growth-inhibiting
chemicals into soil
• Generalists
• High genetic variability
Characteristics of
Ecosystems Vulnerable
to Invader Species
Pollution
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.
Example of biomagnification of DDT in an aquatic food chain.
CLIMATE CHANGE
Warming global temperatures are having an
adverse effect on many species.
Coral Reefs are becoming bleached at a high
rate.
Polar Bears are having to swim greater distances
between ice flows to hunt.
OVEREXPLOITATION
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.
OVEREXPLOITATION
Rhinoceros are often
killed for their horns
and sold illegally on
the black market for
decorative and
medicinal purposes.
Case Study:
Rising Demand for Bushmeat in
Africa
Bushmeathunting has caused the local extinction of many animals in West Africa.
Can spread disease such as HIV/AIDS and Ebola virus.
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.
Case Study:
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.
Pelican Island was the nation’s first wildlife refuge.
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).
• Do not buy furs, ivory products, and other
materials made from endangered or threatened
animal species.
• Do not buy wood and paper products
produced by cutting remaining old-
growth forests in the tropics.
• Do not buy birds, snakes, turtles, tropical fish,
and other animals that are taken from the wild.
• Do not buy orchids, cacti, and other plants that
are taken from the wild.
• Spread the word. Talk to your friends and
relatives about this problem and what they can
do about it.
What Can You Do?
Protecting Species