Transcript Extinction

CHAPTER 11
Biodiversity and Conservation
Biology
This lecture will help you understand:
• The scope of Earth’s
biodiversity
• Ways to measure biodiversity
• Background rates and mass
extinction
• Primary causes of biodiversity
loss
• The benefits of biodiversity
• Conservation biology
• Island biogeography theory
• Biodiversity conservation efforts
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HOUSEKEEPING ITEMS
Any highlights from the video and/or the discussion on
hunting? Thanks to Jasmine, Anthem, and Norranda
in Section 1 for their assistance.
 SOLUTIONS meeting Monday at 4 (250, Rm. 308)
 Did anyone go see “No Impact Man”?
 I put some material in the folder about sources for
local food, including some heirloom or heritage
varieties.
 We will do the quiz next week, but will do a review
beforehand.
 to start off today's lecture topic, a short video about a
lion: http://www.youtube.com/watch?v=btuxO
C2IzE
Saving the Siberian tiger
“Except in pockets of ignorance and malice, there is
no longer an ideological war between
conservationists and developers. Both share the
perception that health and prosperity decline in a
deteriorating environment. They also understand that
useful products cannot be harvested from extinct
species.”
– Edward O. Wilson, Harvard University Biodiversity Expert
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Saving the Siberian tiger
• The largest cat in the world
remains only in the Russian
Far East mountains
• Almost extinct from
hunting, poaching and
habitat destruction
• International conservation
groups saved the species
from extinction
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Biodiversity encompasses several levels
• Biodiversity = sum total of all
organisms in an area
- Species diversity
- Genetic diversity
- Ecosystem diversity
FIGURE 9.1
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Species diversity
• Species Diversity = the number or variety of
species in the world or in a particular region
- Richness = the number of species
- Evenness or relative abundance = extent to
which numbers of individuals of different
species are equal or skewed
- Speciation generates new species and adds to
species richness
- Extinction reduces species richness
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The taxonomy of species
• Taxonomists = scientists who classify species using
physical appearance and genetics
-
Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species
• Every species has a two-part scientific name: genus and
species
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Genetic diversity
• All species consist of individuals that vary
genetically from one another to some degree
• Encompasses the varieties in DNA among
individuals within species and populations
• The raw material for adaptation to local conditions
• Populations with low genetic diversity are
vulnerable
- Inbreeding depression = genetically similar
parents mate and produce inferior offspring
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Ecosystem diversity
• Ecosystem diversity = the number and variety of
ecosystems
• Also encompasses differing communities and
habitats
• Rapid vegetation change and varying landscapes
within an ecosystem promote higher levels of
biodiversity
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Some groups contain more species than
others
• Insects predominate over all
other life-forms
- 40% of all insects are
beetles
• Groups accumulate species by
- Adaptive radiation
- Allopatric speciation
- Low rates of extinction
FIGURE 9.4
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Insects outnumber all other species
FIGURE 9.5
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Biodiversity is unevenly distributed
• Latitudinal
gradient = species
richness increases
towards the equator
• Plant productivity
and climate stability
play key roles
FIGURE 9.6
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Latitudinal gradient has many causes
FIGURE 9.7
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Biodiversity loss and species extinction
• Canadian Species at Risk Act uses categorizes:
- Extinction = occurs when the last member of a species
dies and the species ceases to exist
- Extirpation = the disappearance of a particular
population from a given area, but not the entire species
globally
- Endangered = species in imminent danger of
becoming extirpated or extinct
- Threatened = species likely to become endangered in
the near future
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Extinction is a natural process
• Paleontologists estimate 99% of all species that ever
lived are now extinct
• Background rate of extinction = natural extinctions
for a variety of reasons
- 1 extinction per 1 to 10 million species for mammals
and marine species
- 1 species out of 1,000 mammal and marine species
would go extinct every 1,000 to 10,000 years
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Earth has experienced five previous
mass extinction episodes
• In the past 440 million years, mass extinctions have
eliminated at least 50% of all species
• Today’s mass extinction is caused by humans and humans will
suffer as a result of it
FIGURE 9.8
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Humans set the sixth mass extinction in motion
years ago
FIGURE 9.9
Extinctions followed human arrival on islands and continents
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Current extinction rates are much higher
than normal
• The Red List = an updated list of species facing high
risks of extinctions
- 23% of mammal species
- 12% of bird species
- 31 to 86% of all other species
• Since 1970, 58 fish species, 9 bird species, and 1
mammal species has gone extinct
- Actual numbers are undoubtedly higher
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Biodiversity loss is more than extinction
• The Living Planet Index quantifies degradation
- Between 1970 and 2003, the Index fell by 40%
FIGURE 9.10
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There are several major causes of
biodiversity loss
• Reasons for biodiversity losses are multifaceted
and factors may interact synergistically
• Causes of population decline:
- Habitat alteration
- Invasive species
- Pollution
- Overharvesting
- Climate change
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Habitat alteration causes biodiversity loss
• The greatest cause of biodiversity loss
- Farming simplifies communities
- Grazing modifies the grassland structure and
species composition
- Clearing forests removes resources organisms need
- Hydroelectric dams turn rivers into reservoirs
upstream
- Urbanization and suburban sprawl reduce natural
communities
- A few species (i.e., pigeons, rats) benefit from
changing habitats
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Invasive species cause biodiversity loss
• Introduction of non-native species to new
environments
- Accidental: zebra mussels
- Deliberate: food crops
• Island species are especially vulnerable
• Invaders have no natural predators,
competitors, or parasites
• Cost billions of dollars in economic damage
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Pollution causes biodiversity loss
• Harms organisms in many ways
- Air pollution degrades forest ecosystems
- Water pollution adversely affects fish and
amphibians
- Agricultural runoff harms terrestrial and aquatic
species
- The effects of oil and chemical spills on
wildlife are dramatic and well known
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Overharvesting causes biodiversity loss
• Vulnerable species are large, few in number, long-lived, and
have few young (K-selected species)
- The Siberian tiger (The 1989 political freedom in Soviet
Union brought the freedom to hunt)
- Atlantic gray whale
- Sharks
- Gorillas
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Climate change causes biodiversity loss
• Global impact on habitat and biodiversity
• Greenhouse gases modifies global weather
patterns and increases the frequency of extreme
weather events
• Increases stress on populations and forces
organisms to shift their geographic ranges
• Most animals and plants will not be able to cope,
as evolution has been about adaptation
genetically over much more slowly-evolving
time periods.
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Warming has been the greatest in the Arctic
FIGURE 9.13
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Biodiversity provides ecosystem services
free of charge
• Provides food, shelter, fuel
• Purifies air and water, and detoxifies wastes
• Stabilizes climate, moderates floods, droughts, wind,
temperature
• Generates and renews soil fertility and cycles nutrients
• Pollinates plants and controls pests and disease
• Maintains genetic resources
• Provides cultural and aesthetic benefits
• Allows us to adapt to change
The annual value of just 17 ecosystem services = $16 to 54
trillion per year
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Biodiversity helps maintain ecosystem
function
• Biodiversity increases the stability and resilience of
communities and ecosystems
- Decreased biodiversity reduces a natural system’s ability
to function and provide services to our society
• The loss of a species affects ecosystems differently
- If the species can be functionally replaced by others, it
may make little difference
- Extinction of a keystone species may cause other species
to decline or disappear
• Precautionary principle: “To keep every cog and wheel is
the first precaution of intelligent tinkering” (Aldo Leopold)
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Biodiversity enhances food security
• Genetic diversity within crops is enormously
valuable
- Turkey’s wheat crops received $50 billion
worth of disease resistance from wild wheat
• Wild strains provide disease resistance and have
the ability to grow back year after year without
being replanted
• New potential food crops are waiting to be used
- Serendipity berry produces a sweetener 3,000
times sweeter than sugar
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Organisms provide drugs and medicines
• Each year
pharmaceutical
products owing
their origin to wild
species generate up
to $150 billion in
sales
FIGURE 9.15
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Biodiversity provides economic benefits
through tourism and recreation
• Ecotourism is particularly beneficial in developing
countries
- Costa Rica: rainforests
- Australia: Great Barrier Reef
- Belize: reefs, caves, and rainforests
• Incentive to preserve natural areas and reduce
impacts on the landscape and on native species
• Too many visitors can degrade the outdoor
experience and disturb wildlife
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People value and seek out connections with
nature
• Biophilia = connections that humans
subconsciously seek with life
- Our affinity for parks and wildlife
- Keeping of pets
- High value of real estate with views
of natural lands
• Nature deficit disorder = alienation
from the natural environment
FIGURE 9.16
- May be behind the emotional and
physical problems of the young
- evidence suggest that lack of contact
also exacerbates ADD and violence
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Do we have ethical obligations toward
other species?
• Humans are part of nature and need resources to
survive
• Our ethics have developed from our intelligence
and our ability to make choices
• Many people feel that other organisms have
intrinsic value and an inherent right to exist. This
is reflected in “deep ecology” and the animal
rights movement.
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weighing
the issues
Biophilia and
nature deficit disorder
• What do you think of the concepts of biophilia and
“nature deficit disorder”?
• Have you ever felt a connection to other living things
that you couldn’t explain in scientific or economic
terms?
• Do you think that an affinity for other living things is
innately human?
• How could you determine whether or not most people
in your community feel this way?
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Conservation biology arose in response to
biodiversity loss
• Conservation biology =
devoted to understanding
the factors that influence
the loss, protection, and
restoration of biodiversity
- An applied and goaloriented science
FIGURE 9.17
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Conservation biologists work at multiple
levels
• Use field data, lab data, theory, and experiments to
study impacts of humans on other organisms
• Design, test, and implement ways to mitigate impacts
• Minimum viable population = how small a
population can become before it runs into problems
• Metapopulations = a network of subpopulations
- Small populations are most vulnerable to extinction
and need special attention
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Island biogeography theory
• Equilibrium theory of island biogeography = explains
how species come to be distributed among oceanic
islands
- Also applies to “habitat islands” – patches of one
habitat type isolated within a “sea” of others
- Explains how the number of species on an island
results from an equilibrium between immigration and
extirpation
- Predicts an island’s species richness based on the
island’s size and distance from the mainland
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Species richness results from island size and
distance
• Fewer species colonize an island far from the mainland
• Large islands have higher immigration rates
• Large islands have lower extinction rates
FIGURE 9.18
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The species-area curve
FIGURE 9.19
• Large islands contain more species than small islands
- They are easier to find and have lower extinction rates
- They possess more habitats
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Small “islands” of forest rapidly lose
species
• Forests are fragmented by roads
and logging
• Small forest fragments lose
diversity fastest
- Starting with large species
• Fragmentation is one of the
prime threats to biodiversity
FIGURE 9.20
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Captive breeding, reintroduction, and
cloning are single-species approaches
• Captive breeding – individuals are bred and raised
with the intent of reintroducing them into the wild
- Zoos and botanical gardens
• Some reintroductions require international cooperation
- Whooping cranes in Wood Buffalo Park (Canada)
and gulf coast of Texas (U.S.)
• Some habitat is so fragmented, a species cannot
survive once reintroduced
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Protecting biodiversity
• Cloning – a technique to create more individuals and
save species from extinction
- Most biologists agree that these efforts are not
adequate to recreate the lost biodiversity
• Ample habitat and protection in the wild are needed to
save species
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weighing
the issues
Fragmentation and biodiversity
Suppose a critic of conservation tells you that human
development increases biodiversity, pointing out that
when a forest is fragmented, new habitats, such as
grassy lots and gardens, may be introduced to an area
and allow additional species to live there.
• How would you respond?
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Umbrella species
• Conservation biologists use particular umbrella
species as tools to conserve communities and
ecosystems
- helps protect less-charismatic animals
• Flagship species – large and 'charismatic' species
used as spearheads for biodiversity conservation
- The World Wildlife Fund’s panda bear
• Some organizations are moving beyond the single
species approach to focus on whole landscapes
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Both national and international
conservation efforts are widely supported
• 2002: Species at Risk Act stresses cooperation
with landowners and governments to avoid
hostility
• COSEWIC (Committee on the Status of
Endangered Wildlife in Canada) = expert
committee that reports the status of species at risk
• 1973: UN Convention on International Trade in
Endangered Species of Wild Fauna and Flora
(CITES) – protects endangered species by
banning international transport of their body parts
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Other approaches highlight areas of high
biodiversity
• Biodiversity hotspots – prioritizes
regions most important globally
for biodiversity
- Support a great number of
endemic species = species
found nowhere else in the world
- The area must have at least
1500 endemic plant species
(0.5% of the world total)
- It must have lost 70% of its
habitat due to human impact
FIGURE 9.22
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There are 34 global biodiversity hotspots
2.3% of the planet’s land surface contains 50% of the
world’s plant species and 42% of all terrestrial
vertebrate species
FIGURE 9.23
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Community- based conservation is
increasingly popular
• Community-based conservation = conservation
biologists actively engage local people in protecting
land and wildlife
- Protecting land deprives people access to
resources
- Can guarantee that these resources will not be
used up or sold to foreign corporations and can
instead be sustainably managed
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Innovative economic strategies are being
employed
• Debt-for-nature swap = a conservation
organization pays off a portion of a developing
country’s international debt
- In exchange for a promise by the country to set
aside reserves
- Fund environmental education, and
- Better manage protected areas
• Conservation concession = conservation
organizations pay nations to conserve, and not sell,
resources
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Conclusion
• Loss of biodiversity threatens to result in a mass
extinction
• Primary causes of biodiversity loss are:
- Habitat alteration, invasive species, pollution,
overharvesting of biotic resources, and climate
change
• Human society cannot function without biodiversity’s
pragmatic benefits
• Science can help save species, preserve habitats,
restore populations, and keep natural ecosystems
intact
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QUESTION: Review
Which level is NOT included in the concept of
biodiversity?
a)
b)
c)
d)
Species
Genetics
Ecosystems
All of the above are included in this concept
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QUESTION: Review
What happens when a species experiences “inbreeding
depression”?
a) The species becomes too large for the resource base
b) Genetically similar parents mate and produce inferior
offspring
c) Genetically similar parents mate and produce
superior offspring
d) The number and variety of species increases
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QUESTION: Review
According to the concept of “latitudinal gradient,”
which of the following happens?
a)
b)
c)
d)
Species richness increases towards the equator
Species richness decreases towards the equator
Species richness decreases over time
Countries like Canada have many more species than
expected
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QUESTION: Review
Which of the following is the major cause of extinction?
a)
b)
c)
d)
Invasive species
Pollution
Habitat loss
Overharvesting
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QUESTION: Review
Biodiversity does all of the following, except…
a)
b)
c)
d)
Provide ecosystem services
Decrease food security
Maintain ecosystem function
Provide aesthetic benefits
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QUESTION: Review
According to the theory of island biogeography, which
island would have the highest species richness?
a)
b)
c)
d)
A large island, close to the mainland
A large island, far from the mainland
A small island, close to the mainland
A small island, far from the mainland
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QUESTION: Review
A “biodiversity hotspot” is…?
a) An area located near the equator
b) An area that supports few, but large, species
c) An area that contains naturally high numbers of
people
d) An area that contains a large number of endemic
species
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QUESTION: Interpreting Graphs and Data
Where would ecotourists go to view the maximum species
richness on these islands?
a)
b)
c)
d)
Redonda
Montserrat
Puerto Rico
Hispaniola
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