Bumper sticker of the day: "3 kinds of people: Those who can count & those who can't."

Review of Lecture 13: No fighting please: Populations and competition.

1. Terms to know are in boldface in lecture manual.

2. Five parameters measured to understand populations: size, natality, immigration, mortality, emigration.

3. Regulation of population growth can be density dependent (e.g., disease, predation) or density independent (e.g., weather, fire).

4. Interactions between organisms include mutualism (e.g., symbiosis), commensalism (e.g., epiphytic plants), competition (resource, interference, intraspecific, interspecific), predation, herbivory & parasitism.

5. Competition -- usually both organisms suffer; sometimes one wins. The competitive exclusion principle illustrated with species with same niche. The better competitor drives out the weaker competitor (e.g., barley & oats).

6. If the niches are different, species can coexist in an ecosystem. If all the niches are filled, the population either adapts to a different niche (evolves) or is excluded from the ecosystem (extinction).

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Last updated May 1, 1997.