Post on 17-Jan-2016
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Biological Communities
Chapter 17
Pre AP Biology
Spring ‘13
Relationships within an ecosystem
• No one organism can survive by itself. Organisms depend on each other.
Predator-Prey• Predation is a relationship between 2 organisms in which
one is being consumed so that the other can gain energy.• The predator does the eating, the prey gets eaten.
Symbiotic Relationships
• Symbiosis – when two or more species live together in a close, long-term association.
• Three major kinds of symbiosis:
1. Parasitism
2. Mutualism
3. Commensalism
Parasitism
• One organism feeds on another.• Usually lives on or in another larger
organism which is called a “host”• Parasites don’t kill their host.
Mutualism
• Mutualism is a relationship in which both species benefit.
Commensalism
• Commensalism is a relationship in which one species benefits and the other is neither harmed nor hurt.