Download Sustaining Biodiversity: The Species Approach

 Passenger
1900
pigeon hunted to extinction by
 Commercial
 Geological
extinctions
 Human
hunters used a "stool pigeon”
record shows five mass
activities: hastening more
extinctions?
 We
are degrading and destroying
biodiversity in many parts of the world,
and these threats are increasing.
 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.
 The
extinction of the Passenger Pigeon
had two major causes: commercial
exploitation of pigeon meat on a
massive scale[25] and loss of habitat.[77]
 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
 Degraded
aquatic biodiversity


Background extinction- The ongoing extinction of
individual species due to environmental or ecological
factors such as climate change, disease, loss of habitat, or
competitive disadvantage in relation to other species.
Background extinction occurs at a fairly steady rate over
geological time and is the result of normal evolutionary
processes, with only a limited number of species in an
ecosystem being affected at any one time.
Background extinction rate, also known as ‘normal
extinction rate’, refers to the standard rate of extinction in
earth’s geological and biological history before humans
became a primary contributor to extinctions. This is
primarily the pre-human extinction rates during periods in
between major extinction events.
Mass extinction: causes
• Poorly understood, but involve global changes in
environmental conditions.

Levels of species extinction
• Local extinction, or extirpation- Local extinction,
or extirpation, is the condition of a species (or other taxon)
which ceases to exist in the chosen geographic area of study,
though it still exists elsewhere. Local extinctions are contrasted
with global extinctions.
Ecological extinction- is defined as “the reduction
of a species to such low abundance that, although it is
still present in the community, it no longer interacts
significantly with other species.”[1]
 Ecological extinction stands out because it is the
interaction ecology

• Biological extinction- extinction is the end of an organism or
of a group of organisms (taxon), normally a species.
 Habitat
destruction
 Over-hunting (extirpation, poaching, etc)
 Pollution of water, land, and air (global
warming appears to be causing harm to
some species, especially amphibians).
 Habitat fragmentation (isolating tiny
populations, preventing animals from
finding mates).

Endangered species – so few individual
survivors that could be soon become extinct.
• International Union for the Conservation of Nature
(IUCN), or the World Conservation Union.
 Since 1960, published Red List
 In 2007, listed 16, 306 animals and plants that are in danger of
extinction—60% higher than in 1995.

Threatened species - threatened species are
any species which are vulnerable
to endangerment in the near future.
Figure 9.4
Endangered natural
capital. Some species that
are endangered or
threatened with premature
extinction largely because of
human activities. Almost
30,000 of the world’s species
and roughly 1,300 of those in
the United States are
officially listed as being in
danger of becoming extinct.
Most biologists believe the
actual number of species at
risk is much larger.
Grizzly
bear
Kirkland’s
warbler
Utah prairie Swallowtail
dog
butterfly
Giant
panda
Black-footed
ferret
Mountain
gorilla
Florida
panther
Knowlton
cactus
Florida
manatee
Humpback Golden lion
tamarin
chub
Whooping
crane
African
elephant
Siberian
tiger
Northern
Blue whale
spotted owl
California Hawksbill sea
Black
condor
rhinoceros
turtle
Figure 9.5
Characteristics of species
that are prone to ecological
and biological extinction.
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
 Three problems
• Hard to document due to length of time
• Only 1.8 million species identified
• Little known about nature and ecological roles of
species identified
 Document little changes in DNA
• Suggests species survive for 1 to 10 million years
before going extinct.
 Use species–area relationship
• On average, 90% loss of habitat results in a 50% loss
of species living in that habitat.
 Mathematical
models
 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.
 “It
will take 5-10 million years for natural
speciation to rebuild the biodiversity we
are likely to destroy during your
lifetime.”
 1989
international treaty against poaching
elephants
 Poaching
on the rise
 Track
area of poaching through DNA
analysis of elephants
 Elephants
damaging areas of South Africa:
Should they be culled?
 Intrinsic
value, or existence value
• Species have an inherent right to exist and play
their ecological roles, regardless of their
usefulness to us.
 Edward
O. Wilson: biophilia
phenomenon
 Biophobia
 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.
 Habitat
destruction, degradation, and
fragmentation
 Invasive (nonnative) species
 Population and resource use growth
 Pollution
 Climate change
 Overexploitation
Figure 9.11
Natural capital degradation:
reductions in the ranges of four
wildlife species, mostly as the
result of habitat loss and
hunting. What will happen to
these and millions of other
species when the world’s human
population doubles and per
capita resource consumption
rises sharply in the next few
decades? Question: Would you
support expanding these ranges
even though this would reduce
the land available for people to
grow food and live on? Explain.
(Data from International Union
for the Conservation of Nature
and World Wildlife Fund)
 Globally, habitat
loss,
greatest in temperate
biomes, pace picking up in
tropics.
 Endemic species
• Hawaii, the extinction capital of
America—63% of species at risk.
 Habitat
islands
 Habitat
fragmentation
The Bali Mynah is
distributed and endemic to
the island of Bali, where it is
the island's only surviving
endemic species. This rare
bird was discovered in 1910
and is one of the world's
most critically endangered
birds. In fact, it has been
hovering immediately
above extinction in the wild
for several years.
Numbers
Location
Reason(s)
75% of birds species
Sumatra’s lowland forests
Lumber and palm plantations, used for
biofuels
115 bird species
Brazil
Burning/clearing of rainforests for farms
and ranches; 93% loss of Atlantic coastal
rainforest; clearing of savannah-like cerrado
for soybean plantations
30% of bird species,
70% of grassland
species
North America
Habitat loss and fragmentation of breeding
habitat; replaced by roads and other
developments.
28% of species
Worldwide
Introduction of non-native bird-eating
species
52 of 388 parrot species
Worldwide
Pet trade
23 Seabirds
Worldwide
Bycatch from commercial fishing; pollution
40% of waterbirds
Worldwide
Loss of wetlands
 Seabirds
caught and drown in fishing
equipment
 Migrating
birds fly into power lines,
communication towers, and skyscrapers
 Other threats
• Oil spills
• Pesticides
• Herbicides
• Ingestion of toxic lead shotgun pellets
 Greatest
new threat: Climate change
 Environmental
indicators
• Live in every climate and biome
• Respond quickly to environmental changes
• Easy to track
 Economic
and ecological services
Figure 9.13
The 10 most threatened species of U.S. songbirds. Most of these species are vulnerable
because of habitat loss and fragmentation from human activities. An estimated 12% of
the world’s known bird species may face premature extinction due mostly to human
activities during this century. (Data from National Audubon Society)
Cerulean warbler
Sprague’s pipit
Florida scrub jay
California
gnatcatcher
Bichnell’s thrush
Kirtland's
warbler
Black-capped
vireo
Golden-cheeked
warbler
Henslow's sparrow Bachman's warbler
 Vultures
poisoned
from diclofenac in cow
carcasses
 More
wild dogs eating
the cow carcasses
 More
rabies spreading
to people
Figure 9.14
Some of the more than 7,100 harmful invasive (nonnative) species that have been
deliberately or accidentally introduced into the United States.
 Imported
from Japan in the 1930s to
control soil erosion.
“
The vine that ate the South”
 Could
there be benefits of kudzu?
 Argentina
fire ant: 1930s
• Pesticide spraying in 1950s and 1960s worsened
conditions
 Wiped out competitor ant species and made them
more pesticide resistant.
 Burmese
python
 Population
growth
 Overconsumption
 Pollution
 Climate
change
 Pesticides
• DDT: Banned in the U.S. in 1972
 Bioaccumulation
 Biomagnification
 Poaching
plants
and smuggling of animals and
• Animal parts
• Pets
• Plants for landscaping and enjoyment
 When
commercially valuable species
become endangered, black market prices
soar.
 Prevention: research
and education
 We
can use existing environmental laws
and treaties and work to enact new laws
designed to prevent species extinction and
protect overall biodiversity.
 We
can help to prevent species extinction
by creating and maintaining wildlife
refuges, gene banks, botanical gardens,
zoos, and aquariums.
 Concept
9-4C 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.
 Gene
or seed banks
• Preserve genetic material of endangered plants
 Botanical
gardens and arboreta
• Living plants
 Farms
sale
to raise organisms for commercial
 Techniques
for preserving endangered
terrestrial species
• Egg pulling
• Captive breeding
• Artificial insemination
• Embryo transfer
• Use of incubators
• Cross-fostering
 Limited
 Critics
space and funds
say these facilities are prisons for
the organisms