Transcript APES Chapter 9,2009x

Chapter 9
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Passenger pigeon hunted to extinction by 1900
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Commercial hunters used a "stool pigeon”
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Archeological record shows five mass
extinctions
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Human activities: hastening more extinctions?
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Degrading and destroying biodiversity in many
parts of the world and these threats are increasing
: 83% of the earth’s land surface
filling in wetlands, converting grasslands and
forests to crop fields and urban areas
Species are becoming extinct 100 to 1,000 times
faster than they were before modern humans
arrived on the earth (the background rate), and by
the end of this century, the extinction rate is
expected to be 10,000 times the background rate.
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Human activity has disturbed at least half of
the earth’s land surface
◦ Fills in wetlands
◦ Converts grasslands and forests to crop fields and
urban areas
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Degraded aquatic biodiversity
continuous low level of extinction
 extinction rate : expressed as a percentage or
number of species that go extinct/per million
species per year 1/1,000,000=.000001 or
.0001% ( estimated extinction rate before
humans came on the scene)
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 Premature
extinctions due to
◦ Habitat destruction
◦ Overhunting
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Conservative estimates of extinction = 0.01-1.0%
◦ Growth of human population will increase this loss
◦ Rates are higher where there are more endangered
species
◦ Tropical forests and coral reefs, wetlands and
estuaries—sites of new species—being destroyed
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Speciation crisis
Passenger
pigeon
Great auk
Dodo
Golden toad
Aepyornis
(Madagascar)
Fig. 9-2, p. 185
Number of
species
existing
Effects of a 0.1% extinction rate
5 million
5,000 extinct per year
14 million
50 million
100 million
0
14,000 extinct per year
50,000 extinct per year
100,000 extinct per year
50
100
150
Number of years until one million
species are extinct
200
Fig. 9-3, p. 186
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Endangered species – has so individual
survivors that the species could soon become
extinct over all or most of it’s natural range
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Threatened species - abundant in natural
range , but numbers declining
Characteristic
Examples
Low reproductive
rate (K-strategist)
Blue whale, giant
panda, rhinoceros
Specialized
niche
Narrow
distribution
Blue whale, giant
panda, Everglades
kite
Elephant seal,
desert pupfish
Feeds at high
trophic level
Bengal tiger, bald
eagle, grizzly bear
Fixed
migratory
patterns
Rare
Commercially
valuable
Large territories
Blue whale,
whooping crane,
sea turtle
African violet,
some orchids
Snow leopard, tiger,
elephant, rhinoceros,
rare plants and birds
California condor,
grizzly bear, Florida
panther
Stepped Art
Fig. 9-5, p. 188
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Three problems
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Document little changes in DNA
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Use species–area relationship
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Mathematical models
◦ Hard to document due to length of time
◦ Only 1.8 million species identified
◦ Little known about nature and ecological roles of species
identified
 We
should prevent the premature
extinction of wild species because of the
economic and ecological services they
provide and because they have a right to
exist regardless of their usefulness to us.
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Instrumental value
◦ Use value
 Ecotourism: wildlife tourism
 Genetic information
◦ Nonuse value
 Existence value
 Aesthetic value
 Bequest value
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Ecological value
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1989 international treaty against poaching elephants
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Poaching on the rise
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Track area of poaching through DNA analysis of
elephants
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Elephants damaging areas of South Africa: Should they
be culled?
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Intrinsic value: existence value
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Edward O. Wilson: biophilia (inherent kinship
with the natural world)
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Biophobia – against certain organisms
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Vulnerable to extinction
◦ Slow to reproduce
◦ Human destruction of habitats
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Important ecological roles
◦ Feed on crop-damaging nocturnal insects
◦ Pollen-eaters
◦ Fruit-eaters
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Unwarranted fears of bats
The greatest threats to any species are (in
order) loss or degradation of its habitat,
harmful invasive species, human population
growth, pollution, climate change, and
overexploitation.
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Habitat destruction, degradation, and
fragmentation
Invasive (nonnative) species
Population and resource use growth
Pollution
Climate change
Overexploitation
NATURAL CAPITAL
DEGRADATION
Underlying Causes
• Population growth
• Rising resource use
• Undervaluing natural capital
• Poverty
Direct Causes
• Habitat loss
• Pollution
• Commercial hunting and poaching
• Habitat degradation and
fragmentation
• Introduction of nonnative
species
• Climate change
• Sale of exotic pets and decorative
plants
• Overfishing
• Predator and pest control
Causes of Depletion and Premature Extinction of Wild Species
Fig. 9-10, p. 193
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Tropical Biologist Bill Laurance, et al.- edges of
forest fragments invaded by vines which take over
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How large must a forest fragment be in order to
prevent the loss of rare trees? – within 100 meters of
the edge of a forest fragment 36% of the biomass of
old growth trees is lost within 10-17 years
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Habitat loss and fragmentation of the birds’ breeding
habitats
◦ Forests cleared for farms, lumber plantations, roads,
and development
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Intentional or accidental introduction of nonnative
species
◦ Eat the birds
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Seabirds caught and drown in fishing equipment
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Migrating birds fly into power lines, communication
towers, and skyscrapers
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Other threats
◦
◦
◦
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Oil spills
Pesticides
Herbicides
Ingestion of toxic lead shotgun pellets
◦ Climate Change
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Vultures poisoned from diclofenac in cow
carcasses
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More wild dogs eating the cow carcasses
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More rabies spreading to people
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Most species introductions are beneficial
◦ Food
◦ Shelter
◦ Medicine
◦ Aesthetic enjoyment
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Nonnative species may have no natural
◦ Predators
◦ Competitors
◦ Parasites
◦ Pathogens
Deliberately Introduced Species
Purple
loosestrife
Marine toad
(Giant toad)
European
starling
African honeybee
(“Killer bee”)
Water hyacinth
Japanese
beetle
Nutria
Hydrilla
Salt cedar
(Tamarisk)
European wild
boar (Feral pig)
Fig. 9-14a, p. 199
Fig. 9-14b, p. 199
Accidentally Introduced Species
Sea lamprey
(attached to
lake trout)
Argentina fire
ant
Formosan termite Zebra mussel
Brown tree
snake
Asian longhorned beetle
Eurasian ruffe Common pigeon
(Rock dove)
Asian tiger
mosquito
Gypsy moth
larvae
Fig. 9-14b, p. 199
Deliberately introduced species
Purple
European
loosestrife starling
Marine toad
(Giant toad)
African honeybee Nutria
(“Killer bee”)
Water
hyacinth
Japanese
beetle
Hydrilla
Salt cedar
(Tamarisk)
European wild
boar (Feral pig)
Accidentally introduced species
Sea lamprey
(attached to
lake trout)
Formosan
termite
Argentina
fire ant
Zebra
mussel
Brown tree
snake
Eurasian
ruffe
Common pigeon
(Rock dove)
Asian long- Asian tiger Gypsy moth
horned beetle mosquito
larvae
Stepped Art
Fig. 9-14, p. 199
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Imported from Japan in the 1930s
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“ The vine that ate the South” – might spread as
far as the Great Lakes by 2040 if climate change
(global warming) occurs
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Could there be benefits of kudzu? – source of
food, for making paper
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Argentina fire ant: 1930s
◦ Pesticide spraying in 1950s and 1960s worsened
conditions
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Burmese python –imported as a pet from Southeast
Asia. Dumped in the Everglades. By 2100 in most of
southern US
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Prevent them from becoming established
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Learn the characteristics of the species
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Set up research programs
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Try to find natural ways to control them
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Population growth
Overconsumption
Pollution
Climate change
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Pesticides
◦ DDT: Banned in the U.S. in 1972
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Bioaccumulation
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Biomagnification
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Honeybees responsible for 80% of insectpollinated plants; 110 commercially grown crops;
1/3 US fruit and vegetable crops
30% drop in population
Dying due to?
◦ Pesticides
◦ Parasites
◦ Bee colony collapse syndrome
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Environmental impact on polar bears
◦ Less summer sea ice
◦ PCBs and DDT
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2007: Threatened species list
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Poaching and smuggling of animals and plants
◦ Animal parts
◦ Pets
◦ Plants for landscaping and enjoyment
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Prevention: research and education
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Indigenous people sustained by bush meat
More hunters leading to local extinction of
some wild animals
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We can use existing environmental laws and treaties and work
to enact new laws designed to prevent species extinction and
protect overall biodiversity.
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We can help to prevent species extinction by creating and
maintaining wildlife refuges, gene banks, botanical gardens,
zoos, and aquariums.
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According to the precautionary principle, we should take
measures to prevent or reduce harm to the environment and to
human health, even if some of the cause-and-effect
relationships have not been fully established, scientifically
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1975: Convention on International Trade in
Endangered Species (CITES)
◦ Signed by 172 countries
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Convention on Biological Diversity (BCD)
◦ Focuses on ecosystems
◦ Ratified by 190 countries (not the U.S.)
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Endangered Species Act (ESA): 1973 and later
amended in 1982, 1983, and 1985
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Identify and protect endangered species in the
U.S. and abroad
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Hot Spots
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Habitat Conservation Plan (HCP) colony
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Mixed reviews of the ESA
◦ Weaken it
◦ Repeal it
◦ Modify it
◦ Strengthen it
◦ Simplify it
◦ Streamline it
Species listed only when serious danger of
extinction
 Takes decades for most species to become
endangered or extinct
 More than half of the species listed are stable
or improving
 Budget has been small
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Suggested changes to ESA
◦ Increase the budget
◦ Develop recovery plans more quickly
◦ Establish a core of the endangered
organism’s survival habitat
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1903: Theodore Roosevelt- Pelican Island ,
Florida – brown pelican
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Wildlife refuges -547
◦ Most are wetland sanctuaries- trumpeter swan
◦ More needed for endangered plants
◦ Could abandoned military lands be used for
wildlife habitats?
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Gene or seed banks
◦ Preserve genetic material of endangered plants by
storing their seeds in refrigerated, low humidity
environments
Botanical gardens and arboreta
◦ Living plants- 1/3 rd of the world’s species
Farms to raise organisms for commercial sale
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Techniques for preserving endangered terrestrial
species
◦ Egg pulling
◦ Captive breeding
◦ Artificial insemination
◦ Embryo transfer
◦ Use of incubators
◦ Cross-fostering
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Largest North American bird
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Nearly extinct
◦ Birds captured and breed in captivity
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By 2007, 135 released into the wild
◦ Threatened by lead poisoning
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Species: primary components of biodiversity
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Preservation of species
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Preservation of ecosystems