Check revised lecture notes!

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Check revised lecture notes!
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Time Line

• 1.8 MYBP Beginning of Pleistocene
• 1.7 MYBP Ancestral mammoth arrives in America
• 0.2 MYBP Modern humans evolve in Africa
• 0.015 MYBP Modern humans arrive in America
• 0.01 MYBP 135 spp. extinct, last glacial retreat

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Dispersal of Humans
Nature 7 Dec. 2000 p. 653.
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Climate Change in Pleistocene
Humans arrive in Australia
Humans arrive in America
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Australia

• Colonized 50,000 years ago.
• No global warming at this time.
• Offers a natural experiment to compare human
  predation and climate change.

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Genyornis
Gifford Miller, 1999
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Genyornis (1999 Research!)
Miller et al., 1999. Science 283 205-208
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Summary (but 8 years ago!)

• From consideration of all of these stories for
  different continents there does not appear to any
  one factor responsible for the late Pleistocene
  extinctions . . . What is likely is that the
  primary lethal effect was the combination of
  these factors, acting in a synergistic manner on
  a fauna unaccustomed to so many disruptions at
  once. Burney 1993.

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My Opinion

• Human Hunting
• Almost certainly
• More work needed on early social structure
• Humans as Disease Vectors
• Intriguing
• Predator-Prey Theory
• Not an issue in America or Australia
• Relevant to Africa
• Climate Change
• Probably a factor in America

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Are we on the verge of a

• MASS EXTINCTION?

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Review Deterministic Threats

• Change in physical environment
• climate change
• habitat destruction
• pollution
• Change in biotic environment
• Competition
• Predation (including disease and human hunting)
• Mutualism

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Current Extinction Methods of Humans

• Overkill (Stellars sea cow)
• Introduced species
• predators, disease, competitors
• Habitat destruction
• Global climate change
• Warfare

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The Last Stellars Sea Cow, 1768
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Whales Hunted to Near Extinction

• 1800s - A record three year cruise killed lt 100
  whales.
• 1933 - 30,000 whales killed, 2.5 million barrels
  of whale oil.
• 1967 - 60,000 whales killed, 1.5 million barrels
  of oil

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Introduced Predators
Domestic animals become feral predators
Tibbles eats all Stephan Island Wrens (1894)
Brown tree snake (Guam rail)
W.B. Espeut introduces mongooses onto Jamaica
(1872)
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Bird Extinctions in Eastern N.A.
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The Heath Hen Multiple Causes
Nature Conservancy magazine July/August 1998 p.
8-9
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Disease
New Scientist 5 August 2000 p.35. Article by
Debora MacKenzie
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Humans and Disease
http//www.sciencemag.org/cgi/content/full/287/545
2/443
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Lyme Disease
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Deforestation

• 110,000 km2 per year, 20 hectares per minute (A.
  Sommer, 1976)
• 55 km2 per year (an area the size of WV), 10
  hectares per minute (P. and A. Ehrlich
• 150,000 km2 per year, 25 hectares per minute, one
  football field every second (N. Myers 1989).

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Deforestation