Transcript Mar 20 RK - University of San Diego

I.
Exotic Species
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Species invasions may profoundly affect ecosystems
Definition?
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Criteria (Woods and Moriarty, 2001)
1.
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5.
Human introduction
• Direct vs. Indirect
• Intention?
• Is agency important?
Evolution
• “Native”
• How much does a species have to change?
Historical range
• “Exotic”
• How is a historical range determined/defined?
Degradation
• How is “harm” defined? Some species harm & help
Community membership
• What defines a “community”?
I.
Exotic Species
•
Species invasions may affect ecosystems
profoundly
Detrimental exotic species usually are
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Superior competitors
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Ex – European starling
Effective predators
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Ex – Cane toad
Distribution of cane toad in Australia
Wikipedia
I.
Exotic Species
A.
Zebra mussel
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Competitor in Great Lakes and elsewhere
Transported from Europe in ballast water
Fouling organism
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Restricts movement of water through intake
pipes
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Colonizes boat hulls, pier pilings, buoys, etc.
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Fouls other organisms (clams, mussels)
Filter feeder – removes larvae and particulate
material
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Outcompetes native shellfish species for food
and space
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Removes larvae from water
I.
Exotic Species
B.
Mongoose
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Predator in Hawaii, Caribbean, etc.
Introduced to HI in 1883 to combat rats and
snakes in sugar cane fields
Reproduce early and rapidly
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Females can breed at 10 weeks, 2-3x a year,
2-3 young per litter
Prey on native birds, amphibians, reptiles
Nile perch – Lake Victoria
Argentine ants - California
Brown tree snake - Guam
Caulerpa taxifolia - California
I.
Exotic Species
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May be especially detrimental to
biodiversity and ecosystems when
populations of keystone species are
reduced or eliminated
I.
Exotic Species
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Are all exotic species bad?
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What should we do about exotic
species?
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Ex: Eucalyptus in California