| Term | Definition |
| Primary succession | development of communities in a lifeless area not previosuly inhabited by life (ex: lava) |
| Secondary succession | life progresses where soil remains (clear cut forest; forest fire) |
| Mutualism | symbiotic relationship wheer both partners benefit |
| commensalism | symbiotic relationship where one partner benefits |
| parasitism | relationship in which one partner obtains nutrients at the expense of the host |
| natural selection | organisms that possess favorable adaptations pass them onto the next generation |
| keystone species | species whose role in an ecosystem are more important than others, ex: sea otter |
| indicator species | species that serve as early warnings that an ecosystem is being damaged ex: trout |
| most endangered species | have a small range, require large territory or live on an island |
| endangered species | north spotted owl (loss of old growth forest), bald eagle (thinning of eggs caused by DDT), Piping Polver (nesting areas threatened by development) |
| endangered species act | identifies threatened and endangered species in the US, and puts their protection ahead of economic considerations |
| Convention on International Trade in Endangered species | lists species that cannot be commercially traded as live specimens or wildlife products |
| National Environmental Policy Act | environmental impact statements must be done before any project affecting federal lands can be started |