BIOL 117 Lecture 20: Chapter 20 - Mutualistic interactions
23 Jul 2016
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Document Summary
Mutualisms are essential for the survival of organisms between species. For example, some bacteria living within human intestines bene t from the humans by feeding on nutrients, and bene t humans by releasing toxins that kill virulent bacteria that may be harmful. Another mutualistic relationship is between honeybees and owers. If a mutualistic relationship ceases to bene t both organisms, it must be broken off or it will become a parasitic mutualism. There are two types of mutualisms: obligate and facultative. Ammensalism: (-/0) interactions: negative result on one organism from action that has no positive or negative effect on another organism (humans breathe, take in bacteria and kill it) True symbiotic relationship: lichens: fungus and algae. Alga is inside fungus, provides fungus with carbohydrate nutrients. Monday, november 16, 2015: mutualisms are not always together (ex. honeybees on goldenrod). Persists as long as relationship provides some bene t to each other. Once cost of providing outweighs bene t, relationship ends.
