organism lives off the resources of another; good for parasite, bad for host two organisms providing each with something beneficial; good for both one organism gains something from an organism which is unaffected a measure of the number of different species in a community they can resist changes and have a high tolerance highly important species to the community; provides something for all other species a sequence of changes that occur in a community over time something that drastically changes a community or kills many organisms the series of changes to a community occurring from bare rock to forest the series of changes to a community after a disturbance, from soil to forest

1. parasitism

organism lives off the resources of another; good for parasite, bad for host

2. mutualism

two organisms providing each with something beneficial; good for both

3. commensalism

one organism gains something from an organism which is unaffected

4. biodiversity

a measure of the number of different species in a community

5. high biodiversity

they can resist changes and have a high tolerance

6. keystone species

highly important species to the community; provides something for all other species

7. ecological succession

a sequence of changes that occur in a community over time

8. disturbance

something that drastically changes a community or kills many organisms

9. primary succession

the series of changes to a community occurring from bare rock to forest

10. secondary succession

the series of changes to a community after a disturbance, from soil to forest