EEMB 2 Lecture 4: Logistic Growth
6 Feb 2019
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Document Summary
No natural populations can maintain exponential growth indefinitely. Population density typically fluctuates around a constant number of individuals (carrying capacity = k) As population size increases resources become limiting for growth & reproduction. Carrying capacity maximum population size that an environment can support based on resources. Crowding & resource limitation effects the population growth rate. Population growth slows as its density approaches. Implies there is intraspecific competition within the model. Populations of very small organisms fit fairly well. Many populations do not stabilize at k & deviate from the sigmoid curve. Predictions are only correct when (rare) environment is constant, no predators, no competition from other species. Each individual added to population has same negative effect on population growth. Examples of exceptions: isolated plants & flamingos chance events. Clustering too many trees would be detrimental. Only mate when there are thousands of them. Time lag between the negative effect of population size increase & when they are realized.
