Transcript Chapter 11

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.




By 1900 they became extinct from
over-harvest and habitat loss.


Figure 11-1
Habitat loss – forests cleared
Hunters catch one pigeon & lure
others
Feathers – pillows, bones – fertilizer,
meat – food
Females laid one egg per year
Last wild bird shot in 1900
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, ecotourism
• 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 lives.
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.


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 species.
Figure 11-9
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



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 nonnative
Kudzu vine was introduced in the
southeastern U.S. to control
erosion. It has taken over native
species habitats.
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 habitat.
Figure 11-11
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


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 natural
selection.
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)


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, black-footed ferret).
 Legal and illegal trade in wildlife species used as pets or
for decorative purposes.

OVEREXPLOITATION
 Rhinoceros are often
killed for their horns
and sold illegally on
the black market for
decorative and
medicinal purposes.
Figure 11-16
OVEREXPLOITATION




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 species and others
that depend on them
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 country
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).



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.





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.
http://tolweb.org/onlinecontributors/app?service=external
/ViewImageData&sp=23923
Fig. 11-21, p. 246