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Current Leading Causes of Species Extinction
Holocene Extinction Event
???
Holocene Extinction Event
6th mass extinctionSome natural causes such as
deglaciation, natural climatic shifts, natural rate of extinction
Main cause is….
Holocene Extinction Event
6th mass extinctionSome natural causes such as
deglaciation, natural climatic shifts, natural rate of extinction
Main cause is humans.
HOW?
Invasive (introduced) Species
Invasive (introduced) Species
Due to their lack of natural predators and the fact that native species are not adapted to their competition, invasive species are often very successful
Invasive (introduced) Species
Housecats???
84 million in U.S. New data suggests
they kill 2.9 billion birds and 12.5 billion mammals per year
http://theoatmeal.com/comics/cats_actually_kill
Habitat Destruction
85% of old growth forest in U.S. is gone. (some 2nd growth, some other uses)
Habitat Fragmentation
Breaking large ecosystems into smaller ones can lead to extinction.
Smaller islands of habitats can lead to: Loss of genetic
diversity (inbreeding) Inadequate food
supplies for large animals
Overexploitation
Pollution?
Not a major driver of extinction on land
Main pollution problem in water is eutrophication – too many nutrients running into ocean (mainly from agricultural run-off)
Overloaded nutrients cause algae blooms, which cause dead zones in the water due to oxygen deprivation
Guns + Animals = Good???
In U.S., money from every hunting license goes to buy wetlands -> Habitat Preservation
Over $500 million annually, leading to hundreds of thousands of acres of habitat protected in past few decades
In Africa, most funds for wildlife protection comes from hunting fees
So, how are we doing?
Since 1972, we’ve de-listed (saved) 28 species (25 additional species have been down-listed from endangered to threatened
Currently have 1,162 species on the Endangered Species List in U.S.
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