Threats to Biodiversity

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Chapter 3

• Threats to Biodiversity

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Threats to Biodiversity

• Habitat degradation
• Overexploitation
• Invasive species
• Climate change

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Threats to Biodiversity

• Synergystic
• Snowball effect
• Some species more susceptible to threats

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Types of Extinction

• Local
• Global
• Ecological -

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Argentina
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Argentina
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Anthropogenic Extinctions
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Direct impacts
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Patterns of Extinction

• Evidence from
• Extinction rates varied
• Factors affecting extinction rates
• 1
• 2
• 3

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Recall

• Extinction can affect closely associated species
  remaining in the community.

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Cascade Effects

• The loss of a key species triggers
  ___________________ and alters community
  structure.
• Occurs when
• Example sea otters on Pacific Coast

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Ecological release
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Critical species

• Dominant species
• Ecosystem engineers
• Keystone species

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Causes of extinction identified.

• When is a species in danger of becoming extinct?

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IUCN Red List

• Systematic listing of _________________
• Taxonomists, biologists, and conservationists
  evaluate species
• Specific criteria define which category of
  endangerment is appropriate
• Three categories of extinction
• 1
• 2
• 3

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IUCN Red List

• Only 2.5 of described species have been
  evaluated
• Reptiles, invertebrates, and some plant species
  largely unevaluated
• Some species evaluated but not ranked are
  ______________________

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Most threatening factors
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Vulnerability

• Ecology and behavior
• Factors include
• 1
• 2
• 3

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Specialization

• Narrow range of suitable characteristics

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Specialization

• Narrow range of suitable characteristics
• High level in trophic guild

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Specialization

• Narrow range of suitable characteristics
• High level in trophic guild
• Low reproductive rates

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Rare Species

• Highly restricted habitat preferences
• Restricted range
• Low local population densities
• Not to be confused with artificial rarity
• Once widespread and abundant now reduced to small
  population size

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Proximity to humans

• Species

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Laws protecting Biodiversity

• Endangered Species Act (U.S.)
• CITES
• Focus on endangered or threatened species

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Case Study 3.3

• Key Intl. and U.S. Laws Governing Management and
  Conservationof Biodiversity

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Case Study 3.2

• Hope for a Hotspot