| A | B |
|---|
| population | all the organisms of one species that live in a certain place |
| community | all the populations in one ecosystem |
| ecosystem | a community and its nonliving environment |
| ecology | study of relationships among living and nonliving things |
| habitat | the place where an organism lives |
| niche | the way a species lives |
| territory | an area an animal or group of animals defends from others of the same species |
| birth rate | the number of organisms born during a given period of time |
| death rate | the number of organisms that die during a given period of time |
| endangered species | a species in danger of disappearing from the earth because so few are left |
| extinct | no longer existing |
| succession | the series of changes that naturally takes place in a community over time |
| pioneer stage | the first stage of succession |
| climax community | the final stage of succession in a community |
