9.5 Community Interactions
Notes
Species in a community interact in many ways.
- Competition: organisms fight for the same limited resources.
- Predation: a predator eats its prey. Predator and prey populations often rise and fall in cycles.
- Symbiosis is a close, long-term relationship:
- Mutualism (+/+): both benefit (bees and flowers).
- Commensalism (+/0): one benefits, the other is unaffected (barnacles on a whale).
- Parasitism (+/-): one benefits, the host is harmed (ticks on a dog).
- Succession: a community changes over time. Primary succession starts on bare rock (after lava) with pioneer species like lichens; secondary succession starts where soil remains (after a fire).
Practice
Clownfish live among sea anemone tentacles and are protected, while they clean the anemone and drive off some predators. This is:
Both species benefit.
A tapeworm lives in a dog's intestine and absorbs its food. This is:
The tapeworm benefits and the dog is harmed.
A forest burns down but the soil remains. Grasses grow back first, then shrubs, then trees. This is:
Succession that begins where soil is still present is secondary.
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