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Chapter 11
Sustaining Biodiversity:
The Species Approach
Core Case Study:
The Passenger Pigeon - Gone
Forever


Once the most numerous bird
on earth.
In 1858, Passenger Pigeon
hunting became a big
business.

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

Figure 11-1
Habitat loss – forests cleared
Hunters catch one pigeon & lure
others
Feathers – pillows, bones –
fertilizer, meat – food
By 1900 they became extinct
from over-harvest and
habitat loss.
SPECIES EXTINCTION
 Species



can become extinct:
Locally: A species population 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. (forever)
Global Extinction
 Some
animals have become prematurely
extinct because of human activities.
Figure 11-2
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.
The first species to
go tend to be the big,
the slow and the
tasty ones; those
whose valuable parts
can be sold.
Fig. 11-3, p. 224
SPECIES
EXTINCTION
 Some
species
have
characteristics
that make them
vulnerable to
ecological and
biological
extinction.
Figure 11-4
SPECIES
EXTINCTION
SPECIES EXTINCTION
Biologists use measurements and models to estimate
extinction rates.

Background extinction, mass extinctions, and mass
depletions account for a loss of 99.9% of all species that
have ever existed.


Extinction spasm describes the loss of a large number of
species within a few centuries.
Predicting extinctions is always difficult because of three
factors.



Usually takes a long time , so is difficult to
document/prove.
Only a small percent of the world’s species have even
been identified.
We know very little about most of the world’s identified
species.
SPECIES EXTINCTION
Various methods are used to estimate extinction rates:




Study past records
Current Scientific data (IUCN Redlist)
Base-line info on change in biodiversity over time
Species-area curves
• When 90% of an area is lost, ~50% species are extinct
Predicting population sizes, measure habitat
changes/availability and species interactions
Figure 2. Global Living Planet Index, 1970-2005
The Living Planet Index measures population size of hundreds of
species, to determine a global trend in biodiversity. It has declined
27 percent from 1970 to 2005.
Source: WWF, 2008
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.








Lower Risk (LR) was a catch-all category which includes common species as well as those for which there may be
conservation concern, but which do not warrant a higher category. Category was removed , promoting its subcategories to full
categories.

LR/cd (Conservation Dependent) stable and sizable populations depend on sustained conservation activity.

NT (Near Threatened, formerly LR/nt), close to qualifying for listing as Vulnerable but not fully meeting those criteria;
slowly declining or fairly small populations but probably no danger of going extinct even without conservation activity in the
foreseeable future, or threats suspected to affect taxon in the near future but still avoidable.

LC (Least Concern, formally LR/lc), species that have been evaluated and found to be so common that no conservation
concern is projected in the foreseeable future.

Examples: LR/cd: Coast Redwood; LR/nt: Bigcone Douglas-fir; LR/lc: Leopard (the species as a whole), Orca, House
Sparrow.
Vulnerable (VU): faces a considerable risk of extinction in the medium term.

Examples: Ring-tailed Lemur, Great White Shark, Royal Poinciana.
Endangered (EN): faces a high risk of extinction in the near future.

Examples: Blue Whale, Desert Bighorn Sheep, Giant Panda, Black-footed ferret
Critically Endangered (CR): faces an extremely high risk of extinction in the immediate future.

Examples: Slender-billed Curlew, Spanish Lynx, Red Wolf.
Extinct in the Wild (EW): captive individuals survive, and/or the species has been reintroduced outside its former natural
range, but the species otherwise matches the criteria for "Extinct", such that no free-living, natural population is believed to
exist. "Extirpated" is a term used for localized extinctions of extant species; it always refers to a specific area where the species
no longer exists.

Examples: Hawaiian Crow, Scimitar Oryx.
Extinct (EX): extensive and appropriate surveys have failed to record any living members.

Examples: Thylacine, Dodo, Huia.
Data Deficient (DD): a taxon is listed as Data deficient when there is inadequate information to make an assessment of its risk
category,
Not evaluated (NE): taxa whose conservation status has not been assessed to date.
Video: Penguin Rescue
Videos/penguin_rescue.html

From ABC News, Biology in the Headlines, 2005 DVD.
SPECIES EXTINCTION
 Estimates
of future extinction vary due
to different assumptions about




total species number
the proportion found in the tropics
rate of clearance of tropics
reliability of methods
SPECIES EXTINCTION
 Percentage
of various species types
threatened with premature extinction
from human activities.
Figure 11-5
SPECIES EXTINCTION
 Scientists
use
models to
estimate the risk
of particular
species becoming
extinct or
endangered.
Figure 11-6
SPECIES EXTINCTION
Estimates of future extinctions are limited:


Not all species are known or studied
Total human impact is unclear
• Current rate of extinction = 1,000-10,000x rate of
normal background extinction
• Current model – 20% plant species gone by 2030, 50%
by 2099
SPECIES EXTINCTION
Greater than predicted rates are likely:
 Exponential population growth
 Biologically diverse “hotspots” are already 25-30% loss
 Possible colonization sites are being eliminated, degraded and
simplified by human activities
• This reduces the rate of speciation = SPECIES CRISIS
IMPORTANCE OF WILD SPECIES
Wild species have ecologic and economic value
 Causing the premature extinction of species
eliminates the services they provide.
 Medicine, genetic information, recreational
value, eco-tourism
• Male lion skin = $1,000; living male lion = $515,000 in
tourism revenue over 7 years
Bats = insect control, pollination, seed dispersal
(keystone species)
INTRINSIC VALUE - an inherent right to exist.

Some distinguish between the survival rights among
various types of species (plants vs. animals).
HABITAT LOSS, DEGRADATION, AND
FRAGMENTATION
The most important causes of premature extinction,
“HIPPO”:
 Habitat destruction, degradation, and
fragmentation (greatest threat to species)
 Invasive species
 Population growth
 Pollution
 Overharvest
Animation: Habitat Loss and
Fragmentation
PLAY
ANIMATION
HABITAT LOSS, DEGRADATION,
AND FRAGMENTATION
 The
greatest threat to a species is the loss,
degradation, and fragmentation of where it
Figure 11-7
HABITAT LOSS, DEGRADATION, AND
FRAGMENTATION
Tropical deforestation is the
greatest species eliminator
(followed by loss of
wetlands and plowing
grasslands)
 Major Habitat
Disturbance:
•
•
•
•
•
•
Agriculture
Commercial development
Water development
Recreation
Grazing
Pollution
HABITAT LOSS, DEGRADATION, AND
FRAGMENTATION
Endemic species - species found nowhere else on
earth and are often found in island habitats.
 Habitat islands - habitats surrounded by a
different one, such as a national park
surrounded by logging, mining, etc.
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Fragmentation leads to species vulnerability to
predators, disease, etc.
Species are limited in their ability to colonize new
areas, find mates and food.
HABITAT LOSS, DEGRADATION,
AND FRAGMENTATION
 Reduction
in
ranges of four
wildlife
species,
mostly due to
habitat loss
and
overharvest.
Figure 11-8
Indian Tiger
Range 100 years ago
Range today
(about 2,300 left)
Fig. 11-8a, p. 230
Black Rhino
Range in 1700
Range today
(about 3,600 left)
Fig. 11-8b, p. 230
African Elephant
Probable range 1600
Range today
Fig. 11-8c, p. 230
Asian or Indian Elephant
Former range
Range today
(34,000–54,000 left)
Fig. 11-8d, p. 230
Video: Bachelor Pad at the Zoo
PLAY
VIDEO

From ABC News, Biology in the Headlines, 2005 DVD.
Case Study:
A Disturbing Message from the
Birds
 Human
activities are causing serious
declines in the populations of many bird
Figure 11-9
species.
Video: Bird Species and Birdsongs
PLAY
VIDEO
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.
Figure 11-10
HABITAT LOSS, DEGRADATION, AND
FRAGMENTATION
 70% of the world’s known species of birds are
declining.
 One in six species is threatened with extinction
due to habitat loss and fragmentation.
 Nonnative species are the 2nd greatest threat to
birds

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Excellent environmental indicators: live in every climate
and biome, respond quickly to environmental changes,
easy to track and count.
Birds ecological roles: control rodents and insects,
pollination of flowering plants, seed dispersal, and
scavengers of dead animals
INVASIVE SPECIES
 Many
Kudzu vine was introduced
in the southeastern U.S. to
control erosion. It has
taken over native species
habitats.
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.
Figure 11-A
INVASIVE SPECIES
 Many
invasive species have been
introduced intentionally.
Figure 11-11
INVASIVE SPECIES
 They
have no natural predators,
competitors, or pathogens in their new
Figure 11-11
habitat.
INVASIVE SPECIES
 They




can trigger ecological disruptions
Wild African honeybee – displaces
natives/impact on native plants
Formosan termite – from China – swarming,
aggressive and destructive
Feral pigs kill livestock, eat crops, spread
disease, cause erosion to stream banks, spread
disease to livestock
Feral cats and domestic cats kill about 568
million birds per year.
INVASIVE SPECIES

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The Argentina fire ant was
introduced to Mobile,
Alabama in 1932 from
South America.
 Most probably from
ships.
 No natural predators.
Extremely aggressive
 Eliminated about 90% of
native ant species,
 caused widespread
agricultural damage
 genetically resistant to
pesticides through
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.
Pollution
 Each
year
pesticides:



Example of biomagnification
of DDT in an aquatic food
chain.

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.
Figure 11-15
OVEREXPLOITATION

Smuggling wildlife: 3rd largest and most
profitable illegal cross-border smuggling activity
after arms and drugs (at least 2/3rds die in
transit)
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More endangered = greater demand
Removal of many top predators – cascade effect
Killing protected species for their valuable parts
or selling live to collectors.
 Killing predators and pests that bother us or
cause economic losses (coyotes, bobcats, blackfooted ferret).
 Legal and illegal trade in wildlife species used as

OVEREXPLOITATION
 Rhinoceros
are
often killed for
their horns and
sold illegally on the
black market for
decorative and
medicinal purposes.
Figure 11-16
OVEREXPLOITATION
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More than 60 bird species, mostly parrots are
endangered or threatened because of the wild bird
trade.
Amphibians, reptiles, mammals and tropical fish are
also being depleted because of pet trade.
Ex-poachers in Thailand are now making more money
taking eco-tourists into the forest than they did by
poaching hornbills. They also protect these birds from
poachers.
Collecting exotic pets and plants (such as orchids and
cacti) kill large numbers of them and endanger these
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:
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.
• Difficult to enforce – varies from country to
PROTECTING WILD SPECIES:
LEGAL AND ECONOMIC
APPROACHES
 Convention
on Biological Diversity (CBD)
binds governments to reverse the global
decline in biological biodiversity.


United States has not ratified this treaty.
There are no severe penalties or other
enforcement mechanisms in place.
ESA – Endangered Species Act:
•Program for the conservation of threatened and
endangered plants and animals and the habitats in which
they are found.
•Lead federal agencies: the U.S. Fish and Wildlife
Service (FWS), U.S. National Oceanic and Atmospheric
Administration (NOAA) Fisheries Service. The FWS
maintains a worldwide list of endangered species.
Includes birds, insects, fish, reptiles, mammals, crustaceans, flowers, grasses,
and trees.
Prohibits any action that causes a "taking" of any listed species of endangered
fish or wildlife; import, export, interstate, and foreign commerce of listed
species are all generally prohibited.
Moderate
High
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).

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
Forbids federal agencies (besides defense
department) to carry out / fund projects that
would jeopardize an endangered species.
Makes it illegal for Americans to engage in
commerce associated with or hunt / kill /
collect endangered or threatened species.
Based on biological facts/protects habitats
(HCPs – inadequate science, many are political
compromises)
The U.S. Endangered Species Act
 Biodiversity
hotspots in relation to the
largest concentrations of rare and
potentially endangered species in the U.S.
 Political pressure/lack of funds limit (79%
of plans not implemented)
Figure 11-18
Endangered Species
 Because
of
scarcity of
inspectors,
probably no
more than
1/10th of the
illegal wildlife
trade in the
U.S. is
discovered.
Figure 11-19
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.
Figure 11-20
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.



Many reintroductions fail: no suitable habitat, not able
to survive, renewed overhunting/capture
Large population is needed to maintain capacity for
evolution
Video: Hsing Hsing Dies
PLAY
VIDEO

From ABC News, Biology in the Headlines, 2005 DVD.
RECONCILIATION ECOLOGY
 Reconciliation
ecology – find ways to share
places we dominate with other species.

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
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).
Maintain diverse yards with natives/
biodiverse gardens/rooftop gardens
Bluebirds project & Golden State Park
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.
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 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.
Fig. 11-21, p. 246