33 - 1 Lecture 33 Extinction • Predicting extinction •...

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Unformatted text preview: 11/14/10 1 Lecture 33: Extinction • Predicting extinction • Causes of population declines • Causes of extinction • Example: Dusky Seaside Sparrow Last Tasmanian Tigers in Captivity, 1933 Brown Tree Snake — from the USDA Website Causes of Extinction • Loss of ___________________ • ________________ stochasticity • ________________ stochasticity • _____________________ Loss of genetic variation • Caused by lack of _____________ & other problems in very small populations ( <50 individuals). • Example: _____________ Demographic stochasticity* • Random changes in characteristics of small populations ( _______ individuals). • __________________________, breeding success, etc. *(stochasticity = randomness) 11/14/10 2 Environmental stochasticity • Random changes in local environment affecting small populations ( ________ individuals) • Examples: • “An unusually late frost” or “a very wet spring” Catastrophes • Larger, rare environmental events. – Can affect populations of _________ ____________ . • Examples: hurricanes, large forest fire, widespread disease outbreak, etc. Take-home rules • If your population is very small (<500), then management should _______________________....
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This note was uploaded on 04/06/2011 for the course FNR 103 taught by Professor Staff during the Fall '08 term at Purdue.

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33 - 1 Lecture 33 Extinction • Predicting extinction •...

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