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to being a better competitor on its preferred soil Galium sylvestre Galium saxatile 17 History and Dispersal affect distribution
Dispersal = movement away from area of origin X Darwin’s observation: rabbits do not occur in Australia.
Darwin’s hypothesis: Abiotic & biotic factors do not prevent their occurrence
but instead it is because:
A. they didn’t evolve there
B. they didn’t disperse there 18 History and Dispersal
A test of Darwin’s hypothesis
Introduced species: the rabbit.
24 Released for hunting in Australia ca. 1859.
Population grew to 2 million in 10 yrs. Myxoma virus
(1950) • Myxoma virus,
introduced in 1950
• Spread by mosquitoes
• Killed 99.8% of
infected rabbits 19 Dispersal can affect distribution
Natural range expansion of Cattle egrets
• Native to southern Spain and Portugal
and a few other areas in Africa and Asia
• Spread to S. Africa in early 1900s
• Spread to S. America in late 1800s
• Arrived in Florida in 1940s Figure 52.19 (Campbell 9th ed) 23 Dispersal by humans Introduced species: red imported fire ant (Solenopsis invicta).
Accidentally introduced from S.A. (ca. 1930) to Alabama Native Distribution http://www.ars.usda....
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- Fall '10
- Ecology, aquatic biomes