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Types of Extinction
• 1. Local Extinction: occurs when a species no longer
occurs in area where it was once found
• 2. Ecological Extinction: occurs when so few
members of a species are left that it can no longer
play its ecological role where it is found
• 3. Biological Extinction: occurs when a species no
longer occurs anywhere on Earth. Examples:
Passenger
pigeon
Great Auk
Dodo
Dusky seaside
sparrow
Aepyornis
(Madagascar)
Fig. 22.6, p. 555
Mass Extinction vs. Background extinction
Background extinction : extinction is a natural
process, each year a relatively small number
of species become extinct naturally. The
average is about one species per million per
year. .0001%
Mass extinction is when there are periods when
many organisms become extinct over
thousands of years. These are followed by
periods of adaptive radiation when diversity
increases
Aldo Leopold said that we know very little of the
ecological roles of the world’s species. Until
we know more we should use the precautionary
principle.
Geological Periods
Number of families
of marine animals
Carboniferous
Cretaceous
Devonian
Jurassic
Silurian
Triassic
Tertiary
Ordovician
Permian
Quaternary
Cambrian
800
Mass extinctions
600
?
400
200
0
570
505
438
360
408
286
208
245
Millions of years ago
144
65
0
2
Fig. 22.10, p. 558
The extinction crisis
Many scientists believe there is ample evidence to show
that we are in the middle of the six mass extinction.
– WWF found that 34%fish, 25%amphibians,
24%mammals, 20%reptiles, 14% plants, 12%birds are
under threat of extinction
– 11,046 plant and animal species are at risk of becoming
extinct.
– In the US 539 species have become extinct and 33% are
threatened
– At a 1% extinction rate 1/5 of the species will be gone by
2030
– Many scientists believe it is higher than this
Arctic Circle
60°
EUROPE
NORTH
AMERICA
30°N
Tropic Of Cancer
Pacific
Ocean
0°
150°
120°
90°
Tropic Of Capricorn
ASIA
Atlantic
Ocean
AFRICA
30°W
SOUTH
AMERICA
0°
Pacific
Ocean
60°E
90°
150°
Indian
AUSTRALIA
Ocean
30°S
Antarctic Circle
60°
ANTARCTICA
Critical and endangered
Threatened
Stable or intact
Projected Status of Biodiversity
1998–2018
Fig. 22.3, p. 552
There are three main things that may make the
extinction even worse.
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We are destroying, simplifying and degrading coral
reefs, tropical forests, wetlands and estuaries that
have in the pass served as important centers for
the recovery of biodiversity after mass extinction
and reducing the rates of speciation
This is the fastest that it has ever happened in
history
Human population will accelerate losses.
The difficulty in estimating the
extinction rate
• 1. extinction takes a long time and is difficult
to estimate
• 2. scientists have only identified 1.4 million
species of the world’s 4 to 100 million
• 3. scientists know little of the species they are
trying to document.
• The RED LIST: 16,000 species at risk of
extinction compiled by World Conservation
Union
Characteristic
Examples
Low reproductive rate
(K-strategist)
Blue whale, giant panda,
rhinoceros
Specialized niche
Blue whale, giant panda,
Everglades kite
Narrow distribution
Many island species,
elephant seal, desert pupfish
Feeds at high trophic
level
Bengal tiger, bald eagle,
grizzly bear
Fixed migratory patterns
Blue whale, whooping crane,
sea turtles
Rare
Many island species,
African violet, some orchids
Commercially valuable
Snow leopard, tiger,
elephant, rhinoceros,
rare plants and birds
Large territories
California condor, grizzly
bear, Florida panther
Fig. 22.8, p. 558
Threatened vs. Endangered:
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Threatened means that it is still abundant,
but the numbers are rapidly declining and it
is likely to become endangered.
Endangered: when there are so few animals
that the species could become extinct over
most of its range.
Florida
manatee
Northern spotted Gray wolf
owl (threatened)
Florida panther Bannerman's
turaco (Africa)
Devil's Hole
pupfish
Snow leopard
(Central Asia)
Black footed
ferret
Symphonia
(Madagascar)
Utah prairie dog
(threatened)
Ghost bat
(Australia)
California
condor
Black lace
cactus
Black rhinoceros Oahu tree
(Africa)
snail
Fig. 22.7a, p. 556
Grizzly bear
(threatened)
Arabian oryx
(Middle East)
White top
pitcher plant
Mojave desert
tortoise
(threatened)
Swallowtail
butterfly
Humpback
chub
Kirtland's
warblers
Golden lion
tamarin
(Brazil)
African elephant
(Africa)
Siberian tiger
(Siberia)
Fig. 22.7b, p. 557
West Virginia spring
salamander
Giant panda
(China)
Mountain gorilla Swamp
(Africa)
pink
Knowlton
cactus
Whooping
crane
Pine barrens Hawksbill sea
turtle
tree-frog
(male)
Blue whale
El Segundo
blue butterfly
Fig. 22.7c, p. 557
•
Critical population density (minimum viable
population size): critical size of a population
below which reproduction does not take
place. Even though the this species is not
extinct its numbers will continue to decline
Why preserve wild species
– Economic and medical importance
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90% of today’s food crops were domesticated from
wild plants
Genetic engineers require existing wild species as
sources of genetic material to develop new crop
strains
They supply lumber, dyes, paper, fuel, fiber, oils,
rubber
40% of all medicines (worth 200 billion dollars per
year) were derived from living organisms that mainly
come from the rainforests
Scientific and Ecological importance of
Wild Species
•
•
•
Every species can help scientists understand how life
evolved and functions
Produce oxygen, absorb pollutants, moderate
climate, recycle nutrients, store solar energy, detoxify
toxins, natural pest control
Provide genes for future evolution
Aesthetic and Recreational Importance of
Wildlife
•
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Biophelia: love of nature
A source of beauty, wonder, joy and
recreational pleasure
Americans spend $18.2 billion per year on
ecotourism
Save them because Mrs. Sealy likes them
It is Ethically important to preserve wild
species
•
•
Each species has a right to exist unrelated to its
usefulness to us
It is ethically wrong for us to hasten the extinction of
any species, and we have the ethical responsibility to
protect species from premature extinction.
Causes of premature Extinction
• 1. Underlying Causes
- population growth
- Economic systems that fail to value the
ecological services
- High per capita resource use.
Causes of Premature Extinction
• HIPPO
•
•
•
•
•
H: habitat degradation and fragmentation
I: invasive species
P: pollution
P: population of humans increasing
O: overharvesting and poaching
Direct causes
•
•
Habitat Loss and Fragmentation:
In order of decreasing impact: worst: rainforests,
coral reefs, wetlands, grasslands, pollution of
The map shows important Aspen
stands
(shown in red), the open
freshwater.
Birch (with some Aspen) wood mix
in orange) and commercial
• (shown
Habitat
fragmentation (1st) increases exposed
conifer woodlands. The
commercial
coniferarea
woodlandmaking
at
surface
animals more vulnerable to
Balliefurth forms an effective
barrier
and block to Aspen
species
predator,
disease,
etc.
(2nd)
patches
are
to
small
to
dispersal and movements in
support viable populations (3rd) creates barriers
Strathspey.
that limit species ability to colonize new areas.
. Direct causes
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•
Commercial Hunting and Poaching: Illegal
sale of species, $12 billion per year
organized crime has been getting involved in
smuggling
Bushmeat: hunting wild animals for food is
depleting many of the great apes and
monkeys
. Direct causes
•
Over fishing: Only large fish are caught-all
other animals are thrown back dead or
dieing (overcatch)- drift-net fishing is the
worst, everything that touches this “invisible
curtain of death” dies
. Direct causes
•
Predator and Pest Control: People
exterminate species that compete for food
and game animals. Wolves, prairie dogs,
parakeets, elephants, coyotes.
. Direct causes
• Market for exotic Pets and decorative Plants:
For every live animal captured and sold 50
others are killed. Birds, amphibians,
mammals, reptiles and tropical fish, exotic
plants like cacti and
. Direct causes
•
Climate Change and Pollution: Global
warming and toxic chemicals
. Direct causes
•
Non-Native Species: Can be accidental or
deliberate, some have no natural predators,
competitors or parasites so they take over
the ecosystem and crowd out other species
called native species
Stopping Invasive Species
• 1. do not allow wild animals to escape
• 2. Inspect imported goods
• 3. Ships replace ballast water with fresh seawater
before entering ports
• 4. Do not trade plants or animals from overseas
• 5. Do not dump your aquarium into local waterways
• 6. Clean your recreational gear before heading home,
such as boots, kayaks, mountain bikes, dive gear etc.
Habitat
loss
Habitat
degradation
Overfishing
Basic Causes
Climate
change
• Population growth
• Rising resource use
• No environmental
accounting
• Poverty
Introducing
nonnative
species
Commercial
hunting
and
poaching
Pollution
Predator
and
pest control
Sale of
exotic pets
and
decorative
plants
Fig. 22.13, p. 564
III. Approaches to Protecting Species
Against Extinction
– Ecosystem approach: legally protect wilderness
areas
– Species approach: protecting endangered
species by identifying them and giving them
legal protection
– Wildlife management approach: manage game
species for sustainable yield. Using hunting laws,
harvest quotas etc.
The Species Approach
Goal
The Ecosystem Approach
Goal
Protect species from
premature extinction
Protect populations of
species in their natural
habitats
Strategies
Strategy
• Identify endangered
species
• Protect their critical
habitats
Tactics
• Legally protect
endangered species
• Manage habitat
• Propagate endangered
species in captivity
• Reintroduce species
into suitable habitats
Preserve sufficient areas
of habitats in different
biomes and aquatic
systems
Tactics
• Protect habitat areas
through private purchase
or government action
• Eliminate or reduce
populations of alien
species from protected
areas
• Manage protected areas
to sustain native species
• Restore degraded
ecosystems
Fig. 22.5, p. 555
Use Treaties:
•
1975 Convention on International Trade in Endangered
Species (CITES). Signed by 169 countries. Lists 900 species
that cannot be commercially traded as live specimens or
wildlife products because they are in danger of extinction. It
also lists 28,000 species whose international trade is
monitored and regulated because they are at risk of
becoming threatened. Problems: enforcement is difficult
and spotty, convicted violators often pay only small fines,
member countries can exempt themselves from protecting
any species that is on the list, much of the highly profitable
trade of these animals goes on in countries that have not
signed the treaty.
Treaties
•
The Convention on Biological Diversity:
Signed during the 1992 Rio Earth Summit.
Ratified by 188 countries. The US has
refused to ratify this treaty, which has
hindered progress. Countries commit to
preserving wild species
Use Laws
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•
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Endangered Species Act: (1973, 2006) makes it illegal for
Americans to trade, kill or use any product from an
endangered species. (Unless for scientific purpose or
enhance the survival of the species. Currently the list has
over 1,260 species (60% animals 40% plants)
Also makes it illegal for state or federal governments to
authorize any project that will jeopardize an endangered
species.
1,260 on the list, 50-85 added every year
Fish and Wildlife and National Marine Fisheries put
together the list
»
All species that are listed are required to have a “critical habitat”
needed for its survival and recovery – only ¼ currently have a plan
Bad Politics
»
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In 1996 this act was almost replaced by U.S Congress who were
being backed by timber, mining, and private industry.
Tried to make wildlife protection voluntary on private land
Attempted to have government pay landowners if their land was
unusable in order to protect an endangered species – regulatory
taking
Make it harder and more expensive to list newly endangered
species by tying up government wildlife officials in hearings and
pre-review panels
Allowing secretary of the interior the power to allow a listed
species to become extinct -God Squad
give landowners exemptions from the law, and prohibiting the
public from commenting or filing lawsuits to change poorly
designed habitat conservation plans. “HCPs”
• ***Opponents say ESA has been unsuccessful
because only a few species have been
removed from the list. However, many
populations have stabilized – 40%
Strengthen the ESA
•
•
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Find out what ecosystems we have.
Protect most endangered ecosystems.
Offer financial incentives to private landowners to protect
species.
•
Operates on very limited funds. So we need
to decide which species to save.
Environmentalists want the following
considered:
Have the best chance for survival.
•
» Have the most ecological importance to the ecosystem.
» Potentially useful for agriculture, medicine or industry.
» Some say we don’t have enough info to make these
decisions.
Encouraging Private Landowners to
Protect Species
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•
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Use Habitat Conservation plans which allow landowners to
kill a certain number of endangered species in exchange for
protecting species. This could include setting aside part of
the species habitat as a preserve, paying to relocate the
species, paying the government money to set up a suitable
habitat elsewhere.
safe Harbor agreements- voluntary agreement to maintain
habitat in exchange for technical assistance and assurances
of no further future restrictions
candidate conservation agreements – agree to save species
not yet listed in exchange for govt subsidies
Conservation
•
Conservation
Easements: The
Nature Conservancy
has preserved 10,800
square miles by
buying the land.
•
Wildlife Refuges: 508 refuges, 20% endangered
species inhabit them.
•
Gene Banks & Botanical Gardens: storing
seeds under refrigeration. Expensive,
doesn’t work with all seeds, to little storage
capacity.
•
Zoos
Zoos: focus on large charismatic animals; rely on
egg pulling & captive breeding. Most
reintroductions fail. Lack of space & money cant
support the minimum # of animals needed to
sustain the pop.
Wildlife Management
• 1.Manipulation of wildlife populations for their welfare & human benefit.
• 2. 90% is devoted to producing surpluses of game animals & game birds.
• 3.Wildlife manages the growth of plant species that are the best cover &
food for game animals.
• 4. Sport hunting: sport-hunting laws to manage populations of game
animals- like limits on age, sex, number, etc. Proponents of hunting claim
we need to keep down the # of deer because there is a population
explosion. Opponents say a surplus is deliberately created and that the
deer is used as a smoke screen to hunt many other animals.
• Management of Migratory Waterfowl: ducks, geese, song –birds that fly in
north-south routes called flyways. International Treaties to protect
habitats, regulate hunting Bonn Germany