Lect 06 PP outline

Lect 06 PP outline - Evolution, Biological Communities, and...

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Evolution, Biological Communities, and Species Interactions Interactions When to two or more different species are present they have the potential to interact We have seen how competition for resources, and predation, can be forces in evolution. Not all interactions are negative, however. Let’s look at a few different interactions…. SPECIES INTERACTIONS A predator is an organism that feeds directly upon another living organism, whether or not it kills the prey in doing so. Herbivores Carnivores Omnivores Predation Prey most successfully on slowest, weakest, least fit members of target population. - Reduce competition, population overgrowth, and stimulate natural selection. Co-evolution - An “arms race” between predators and prey. - Defensive mechanisms - Species exert selective pressures on each other Parasitism Parasites live on or in another organism and take resources from it, generally without killing the host. Some cause little harm Others can be lethal Gross-out alert… Keystone Species Keystone Species - A species or group of species whose impact on its community or ecosystem is much larger and more influential than would be expected from mere abundance. Often, many species are intricately interconnected so that it is difficult to tell which is the essential component. - Kelp – sea urchins – sea otters Competition Interspecific - Competition between members of different species. Intraspecific - Competition among members of the same species. Often intense due to same space and nutritional requirements.
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This note was uploaded on 04/26/2008 for the course BIOLOGY 118 taught by Professor Richardson during the Spring '08 term at Winona.

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Lect 06 PP outline - Evolution, Biological Communities, and...

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