Population Interactions Ecosystems are made of many populations living together How do populations live together? ◦ 5 types community interactions Competition Mutualism Commensalism Parasitism Predation Organisms compete for same resources (food, space, etc) Nature doesn’t like competition ◦ Reduced through species occupy different NICHES – the physical and biological conditions Include: Food types Predators Temperature needed to survive An interaction in which organisms of both species benefits +/+ relationship In other words: Let’s work together! Example: Bees and flowering plants An interaction in which one organism benefits (the commensal) and the other organism has no benefit or harm (the host) +/0 relationship In other words: I don’t care what you do as long as it doesn’t affect me. Example: Clownfish and sea anemone An interaction in which one organism benefits (the parasite) and the other organism is harmed (the host) +/- relationship In other words: I’m stealing from you! Example: Ticks and Dogs 1. 2. 3. Predation and parasitism are both +/interactions, but there are several differences The parasite is often much smaller than the host. The parasite consumes only a small amount of the host at a time. Predators will eat most of their prey Parasite can use host for other (protection, reproduction, etc). Predation only for food http://www.youtube.com/watch?v=63UAB4J2 r7Y Hookworms Strangler Fig Zebra Mussel Tongue Eating Louse