Biodiversity and Endangered Species

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Biodiversity: the variety of life
  • Aldo Leopold (1947) "the first requisite of intellegent tinkering is to save all the pieces."
  • 115 bird species have gone extinct in the last 400 years
    • Great Auk (Alca impennis)
    • Dodo (Raphus Cucullatus)
    • Passenger pigeon (Ectopistes migratorius)
  • 191 mollusc species in 400 years
  • 600 plant species in 400 years
  • Freshwater Fish: 20% of all species extinct or endangered next
    Plants and Animals in USA, Nature Conservancy, 1996


Trends in biodiversity

Listing the species
  • Linnean Shortfall: 1.4 million species described, but total diversity unknown estimated 5 - 50 million
  • Centilenan Extinctions: extinction of undescribed species

Global Diversity of Organisms

Global Diversity of Taxonomists
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after Barroclough (1992)




Human Impact

  • 20-40% total global primary production
  • 70% marine primary production
    (Vitousek et al [1997] after Brown and Lomolino [1998])

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Geographic Variation in Biodiversity

  1. tropical maximum
  2. area - diversity relationship
  3. isolation diversity relationship
  4. area and isolation vs. endemicity

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Biodiversity Hot Spots: regions of high endemicity and high diversty
Restricted-Area Species (endemics)
  • Rain Forests
    • 7% of Earth's surface
    • 50% of Earth's species

    (Bibby et al [1992] after Brown and Lomolino [1998])

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Biodiversity Hot Spots: regions of high endemicity and high diversty
  • Endemic Bird Areas (EBA): two or more endemic birds
    • Tropical maximum of EBA's
    • 1/2 of all endemic birds are on islands (which constitute 1/10 of land surface)
Endemic Bird Areas
(Bibby et al [1992] after Brown and Lomolino [1998])

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Biodiversity Hot Spots: regions of high endemicity and high diversty
Terrestrial Hot Spots
  • Hotspots are concentrated
      Bird hotspots just 5% of Earth's surface
  • Do Hotspots Overlap for birds, other animals, plants?
    • Diversity Centers Do not necessarily match
      • Central America: Birds and Reptiles similar, reptiles different
      • Africa: Amphibians and Mammals similar, Birds and plants different

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Marine Hot Spots

  • Diversity maximum 2000 - 3000 m (slope)
  • Endemicity maximum 6000 m (hadal zone)
    • Hydrothermal Vent Communities
        One new phylum, 14 new families, 50 new genera

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Prehistoric Record of Extinctions

  • K-T boundary extinctions 50% of all species, globally
      Greatest number of extinctions tropical
  • Great American Interchange (3.5 million years)
  • Deglacial Megafaunal Extinction
    Exctinctions: 1600-2000
    (World Conservation Monitoring Center [1992] after Brown and Lomolino [1998])

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Historic Record of Extinctions

  • Islands biotas most susceptible
  • 2/3 of the island extinctions have been caused by humans
  • Hawaii: Polynesians responsible for 1/2 faunal extinctions
  • New Zealand: Maori caused extinction of 11 species of Moas

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Species Introductions: Exotic Invasions


C - Continent, S - Continental Island, O - Oceanic Island
Mammal Species / Bird Species
(Ebenhard [1988] after Brown and Lomolino [1998])

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Species Introductions: Exotic Invasions

  • Austrialia and New Zealand receive most
  • 48/137 of Californian fish are exotic
  • 67/95 of Arizonan fish are exotic
  • Lake Victoria (Africa) 200 species extinct due to invasion of Nile perch (Lates niloticus)

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Invasion of Island Biotas

  • Nearly 1/2 of the Plants of New Zealand are Exotic
  • The Hawaiian Biota
    • 45% of Plants Introduced
    • 42% birds
    • 94% mammals
    • 100% reptiles
Affect of introduced Rats on Islands (New Zealand) and Mongoose (Pacific Islands) on diversity

(Whitaker [1978])


(Case & Bolger [1991])

Rats on Islands (New Zealand) and Mongoose (Pacific Islands)

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Invasion of Island Biotas

Resistance to Invasion

    Birds and Mammals in the Pacific Region
    (Brown [1989] after Brown and Lomolino [1998])

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Invasion of Island Biotas

Effect of Isolation

    (Greenway [1967] after Brown and Lomolino [1998])
    Birds on Pacific Islands

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Invasion of Island Biotas

Effect of Island Area on Extincton Rates

    (Greenway [1967] after Brown and Lomolino [1998])
    Birds on Pacific Islands

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Factors Threatening Endangered Species

Habitat Loss & Habitat Fragmentation

Mollusk Extinction in the Historic Period

  • Habitat Loss & Pollution(60%)
  • Introduced Species (24%)
  • Human Harvesting (14%)
  • Other (2%)
      Climate Change

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Factors Threatening Endangered Species

Exotic Species

    (Case [1996] after Brown and Lomolino [1998])
    Birds on Pacific Islands

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Historic Global Pattern of Extinctions


    (WCMC [1992] after Brown and Lomolino [1998])

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Plant Extinction in the Historic Period

  • Habitat Loss & Pollution(55%)
  • Introduced Species (25%)
  • Human Harvesting (10%)
  • Other (9%)
      Climate Change
  • Natural

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Factors Threatening Endangered Species

Habitat Loss & Habitat Fragmentation
  • Creation of habitat islands among cultivated and urban areas

  • Rain Forests
    • Madagascar 7% of rainforests remain
    • Brazilian coastal 1% remain
    • Singapore 1% remain (since 1819)
  • World's Grasslands - 50% remain

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Results of Habitat Fragmentation (Brown's Relaxation)

  • Species restricted to urbanized areas lost
  • Exclusion from resources
      spawning fish
  • Small population of island susceptible to extinction
  • Isolation-related extinction (no rescue effect)
  • Destabalization due to loss of key species
      keystone predators
      commensuals

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Applications of Island Biogeographic Theory to Nature Preserves

SLOSS Single Large or Several Small

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Applications of Island Biogeographic Theory to Nature Preserves


Single Large vs.

Several Small

Circular vs.

"Peninsular"

Close vs.

Spread out

Connected vs.

Unconnected
(Wilson and Willis [1975] after Brown and Lomolino [1998])
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Applications of Island Biogeographic Theory to Nature Preserves

  • Reserves should be as large as possible
      Area - Diversity
  • Unique habitats (biotas) should have multiple preserves (nearby)
      Redundancy
      Isolation
  • Preserves should be round and continuous
      Peninsula effect
      Isolation
  • Priority given to highest endemicity and vulnerability
  • Corridores between preserves should be maintained

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Predicting Effects of Global Change

  • Warming and Species Ranges
  • Migration Northward and to Higher Elevations
      3 oC warming = 1/2 km upward

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