Extinction

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Extinction
Large scale patterns of diversification Spindle
diagrams of diversification/extinction Mass
extinctions (uniqueness, causes,
selectivity) Opportunities for diversification Hum
ans and extinction
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Marine Animals
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End-Permian Extinction
50 of all families, gt90 of all species All
reef-building corals of the time 8 of 27 insect
orders
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K-T Extinction
60-80 of species Dinos, lg. marine reptiles went
extinct. Mammals, ferns, insects, crocodiles,
amphibians largely unaffected.
http//www.wm.edu/geology/virginia
http//www.bio.txstate.edu/upchurch
http//www.geo.vu.nl/smit
http//news.nationalgeographic.com
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Mass extinctions affect some groups more than
others.
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Extinction risk depends on geographic range
Bivalves and gastropods
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Do mass extinctions create opportunities?
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Marine Animals
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The human bolide - are we headed for the 6th Mass
Extinction?
Xerces Blue
Carolina Parakeet
Epioblasma mussels
These are 6 of the gt1000 extinctions observed
between 1600 and 1993
Stellers Sea Cow
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History suggests that humans cause extinction
www.amnh.org
gt80 of megafauna extinct in N. Am., S. Am.,
Australia
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Bird extinctions on Eua (Tonga)
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Bird extinctions on oceanic islands
60 species extinct in last 1500 yrs in Hawaii,
following human colonization.
An estimated 2000 species of flightless rail used
to live on islands in the Pacific
only 4 species remain today.
Approximately 1/5 of all bird species in the
world have gone extinct in association with human
colonization of the Pacific islands.
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Habitat destruction, the 1 cause of extinction
today
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Tropical rainforest destruction and extinction
Lots of diversity and high local endemism
A 1 km2 patch of forest in W. Ecuador had 1200
plant species. 25 endemic to W. Ecuador, 43 spp.
only known from this one fragment. In Borneo, a
survey covering an area equal to 20 football
fields found as many tree species as in all of
North America. In Panama, it was estimated that
18,000 beetle species occupied an area the size
of 2 football fields.
Rapid deforestation associated w/ population
growth
In 1989, the surviving rain forests occupied an
area about that of the contiguous 48 states of
the United States, and they were being reduced by
an amount equivalent to the size of Florida each
year E.O. Wilson
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Current estimated extinction rates vs. the Big
Five
Based on rates of deforestation and patterns of
tropical diversity and endemism in the next 30
years, 5-10 of Earths species will go extinct.
Such a rate is 100 to 1000 times the background
extinction rate.
Given the current rate of human population
growth, this rate is likely to continue long
enough to result in a mass extinction.
This would be the first mass extinction caused by
an organism.
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Habitat destruction is not the only extinction
threat
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Zebra mussel
Purple loosestrife
Gypsy moth
Kudzu
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Like the Big Five, human-caused extinction is
selective
Since 1900, 123 freshwater animal spp. have gone
extinct in the U.S.