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Current Extinctions
Rates of Extinction
Expected from Fossil Record:
• 4 species a year go extinct from 10 million
living species
• 1 mammal species (out of about 4000
living) extinct every 400 years
• 1 bird species (out of just over 9000 living)
extinct every 200 years
• 40 plant species extinct in 400 years (out of
250,000 living)
Rates of Extinction
Rates of extinction on mainland areas since
1600
• mammals 1.6% extinct (62 of 4000)
• birds 1.3% extinct (117 of 9000)
• vascular plants 0.3% extinct (596 of
250,000)
Alwyn Gentry and friends in the field
Estimating Loss of Unknown Species
• Based on the Theory of Island Biogeography from
which we know that larger areas support more
species and from which we know that if we reduce
the size of an island, we lose species - this
knowledge is described by the species-area
equation
•
S = cAz
• where S = species number, A = area, c is a
constant that varies depending on the type of
species and the islands in question, z is the slope
of the curve
Extinct Australian Megafauna
Some Extinct
And still living
Pleistocene
Megafauna
Extinct American mega-bird
Recent Pleistocene Extinctions
Past Climate Change
Coring Glacial Ice
Ice Core Data
Pollen core data collection
Pollen Core Data
Distribution of North American Trees in past 16,000 years
Black-tailed prairie dog
Northern bog lemming
Eastern chipmunk
Global Ice Coverage Last Ice Age
Rainforests in: a. Glacial period, b. Inter-glacial period
Global
carbon
cycle
Carbon dioxide concentration at Mauna Loa
Change in Average Global
Temperature
Statistics and climate change
• http://www.youtube.com/watch?feature=pla
yer_embedded&v=e0vj-0imOLw
Surface temperature trends from
1800-2009
• http://www.guardian.co.uk/environment/vid
eo/2011/oct/20/berkeley-earth-climatechange-video
Model predictions of global
temperature increase
Predicted surface change 1960-2060
Current distributions of biomes
Predictions for biomes after global warming
The Earth Ice Free
Global Ice Coverage Last Ice Age
Will species be able to survive
current climate change?
• Maybe
• Maybe not
Pikas may run out of mountaintop
What makes species vulnerable to
extinction?
The dodo
Passenger
pigeon
Passenger
pigeon
Allee Effect
• Some species have a minimum requirement
for population size in order to successfully
breed
Characteristics that predispose
species to becoming extinct
1. habitat overlap - the species occupy habitat that is
desirable to humans and lose out in competition with
humans for the habitat - tallgrass prairie species
2. human attention - species suffer because singled out by
humans - either desired as food or fur and hunted heavily
(passenger pigeon, dodo, northern elephant seal); or
disliked by humans and killed as varmints (wolves,
African wild dogs)
3. large home range requirements - animals needing large
areas can’t find large enough areas in human dominated
landscape - California condor
4. limited adaptability and resilience - Pacific salmon
return to natal stream to reproduce; won’t go elsewhere
Konza Prairie – Kansas
African wild dog
California Condor
Coho salmon
Salmon Life Cycle
Salmon support 137 species