Biodiversity and Endangered Species

• 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
  Plants and Animals in USA, Nature Conservancy, 1996

Trends in biodiversity

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

Human Impact

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

Geographic Variation in Biodiversity

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

   

• Rain Forests
  • 7% of Earth's surface
  • 50% of Earth's species
  
  (Bibby et al [1992] after Brown and Lomolino [1998])

• 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])

• 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

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

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])

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

Species Introductions: Exotic Invasions

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)

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

(Whitaker [1978])

(Case & Bolger [1991])

Invasion of Island Biotas

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

Invasion of Island Biotas

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

Invasion of Island Biotas

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

Factors Threatening Endangered Species

Mollusk Extinction in the Historic Period

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

Factors Threatening Endangered Species

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

Historic Global Pattern of Extinctions

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

Plant Extinction in the Historic Period

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

Factors Threatening Endangered Species

• 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

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

Applications of Island Biogeographic Theory to Nature Preserves

Applications of Island Biogeographic Theory to Nature Preserves

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

Predicting Effects of Global Change