Extinction

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Extinction
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Rare and Endangered Species in Japan
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Threatened and Endangered Species
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Threatened And Endangered Species in Illinois
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Minimum Viable Population

• The smallest population for a species which can
  be expected to survive for a long time
• Many factors effect MVP the study of those
  factors is often called Population Viability
  Analysis or Population Vulnerability Analysis
  or PVA

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Environmental Fluctuations
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Kirtlands Warbler
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Cheetah
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Habitat Fragmentation

• Fragmentation is the transformation of large
  expanse of habitat into a number of smaller
  patches of smaller total area isolated from each
  other by a matrix of habitat unlike the original

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Domesday Book 1085-86
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Selection from the Domesday Book
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Heath Hen Extinction Vortex
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Minimum Viable Population Size

• Another definition - often defined as 95
  probability of 100 year survival, but can also
  plan for longer survival (500 or 1000 years)
• MVP is usually determined by modeling

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Forces which may cause extinction

• 1) deterministic - something essential is removed
  (habitat loss) or something lethal is added
  (pollutant, disease, introduced species) -
  presumably we can act to minimize these risks

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Forces which may cause extinction

• 2) stochastic (random) - environmental,
  catastrophic, demographic and genetic - this is
  what we need to worry about and what is hardest
  to prevent
• environmental randomness effects resources and
  conditions and we can't do much about it
• catastrophic randomness - floods, fires,
  hurricanes, volcanoes - can't really prevent but
  can spread individuals around to minimize the
  impact
• demographic - just natural random variation in
  birth and death rates can lead to extinction
• genetic - lack of genetic variability can lead to
  problems of inbreeding and poor response to
  diseases and environmental change

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Grizzly Bear and 50/500 Rule
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MVP 50/500 Rule?
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English Skylark
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Metapopulation Dynamics
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Metapopulation

• A series of small, separate populations united
  together by dispersal
• Thus even if all members of one population go
  extinct, other populations survive and dispersal
  from survivor populations can recolonize the area
  a rescue effect

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Bay Checkerspot Butterfly
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Population dynamics of Bay Checkerspot Butterfly