Transcript Chapter 11

CHAPTER 11
Sustaining
Biodiversity: The
Species Approach
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.


Marsh Deer, Blue Whale, Lake Sturgeon
Sea otter, California Spiny Lobster
Globally (biologically): Species is no longer found
on the earth.
GLOBAL EXTINCTION

Some animals have become prematurely extinct because of
human activities.
Figure 11-2
ENDANGERED AND THREATENED SPECIES
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.

Figure 11-3
Fig. 11-3, p. 224
SPECIES
EXTINCTION
Some species have
characteristics that
make them vulnerable
to ecological and
biological extinction.
 Florida’s extinction

Figure 11-4
ESTIMATING EXTINCTION RATES

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.

1 out of every 4 mammal species
 1 out of every 7 plant species
 1 out of every 8 bird speices

Figure 11-5
Estimating extinction rates is difficult because
Extinction takes a long time on a human time scale
and documentation is limited
 Many species are not identified
 We know little about the species we have identified

SPECIES EXTINCTION

Percentage of various species types threatened with
premature extinction from human activities.
Figure 11-5
IMPORTANCE OF WILD SPECIES

Ecological services


Control pests, store carbon, recycle nutrients
Economic services

Food, fuel, timber, paper, medicines
Genetic information
 Recreational pleasure
 Ecotourism


Biophilia= affinity for nature
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
HABITAT LOSS, DEGRADATION, AND
FRAGMENTATION

The greatest threat to a species is the loss, degradation, and
fragmentation of where it lives.
Figure 11-7
HABITAT LOSS, DEGRADATION, AND
FRAGMENTATION

Reduction in ranges
of four wildlife
species, mostly due
to habitat loss and
overharvest.
Figure 11-8
WHICH SPECIES ARE MOST VULNERABLE?
Specialist
 K strategist- low reproductive rate
 Contain desirable characteristics
video

CASE STUDY:
A DISTURBING MESSAGE FROM THE BIRDS

Human activities are causing serious declines in the populations
of many bird species due to deforestation, introduction of
nonnative species, nets in oceans, power lines, and
buildings.
Figure 11-9
INVASIVE SPECIES

Many nonnative species
provide us with food,
medicine, and other
benefits (like reduced soil
erosion=kudzu) but a a few
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.
Figure 11-A
INVASIVE SPECIES

Many invasive species have been introduced
intentionally.
Figure 11-11
INVASIVE SPECIES

Many invasive species have been introduced
unintentionally.
Figure 11-11
INVASIVE SPECIES

The Argentina fire ant
was introduced to
Mobile, Alabama in 1932
from South America.
Most probably from
ships.
 No natural predators.


Zebra Mussels in the
Great Lakes
Figure 11-12
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.
Figure 11-13
Characteristics of
Successful
Invader Species
• High reproductive rate,
short generation time
(r-selected species)
• Pioneer species
• Long lived
Characteristics of
Ecosystems Vulnerable
to Invader Species
• Climate similar to
habitat of invader
• Absence of predators
on invading species
• Early successional
systems
• High dispersal rate
• Release growth-inhibiting
chemicals into soil
• Low diversity of
native species
• Absence of fire
• Generalists
• High genetic variability
• Disturbed by human
activities
Fig. 11-13, p. 236
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.


Polar bears
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.
Figure 11-15
OVEREXPLOITATION


Some protected species are killed for their
valuable parts or are sold live to collectors.
Legal and illegal trade in wildlife species used
as pets or for decorative purposes threatens some
species with extinction.

Burmese python
OVEREXPLOITATION

Rhinoceros are often killed
for their horns and sold
illegally on the black
market for decorative and
medicinal purposes.
Figure 11-16
CASE STUDY:
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.

Figure 11-17
PROTECTING WILD SPECIES

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

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.

OTHER ACTS/TREATIES
TO PROTECT
SPECIES


National Marine Fisheries Service- id and
protect threatened or endangered marine species
US Fish and Wildlife Service- id and protect
threatened or endangered terrestrial species
PROTECTING WILD
SPECIES
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).

What Can You Do?
Protecting Species
• 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 oldgrowth 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.
Fig. 11-21, p. 246