Ecology (Biology 250) Notes on Lecture 12

As population size increases logistic growth rate

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Unformatted text preview: side of the equation nears zero.  As population size increases, logistic growth rate becomes a small fraction of growth rate.  Highest when N=K/2.  N/K = Environmental resistance. 1 9/25/11 Logistic Population Growth Logistic Population Growth What causes the rate r to change? Limits to Population Growth  Environment limits population growth by altering birth and death rates.  Density-dependent factors  Resource competition, Predation, Disease  Density-independent factors  Natural disasters Density Independent Factors -Galapagos Finch Population Growth- Density Independent Factors -Galapagos Finch Population Growth Boag and Grant (1984) - Geospiza fortis was numerically dominant finch (1,200).  After drought of 1977, population fell to (180).  Access to food  1983 - 10x normal rainfall Density Independent Factors -Galapagos Finch Population Growth- 2 9/25/11 Cactus Finches and Cactus Reproduction Cactus Finches and Cactus Reproduction  Grant and Grant documented several ways finches utilized cacti:  Finches t...
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This document was uploaded on 03/19/2014 for the course BIO 250 at Xavier.

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