| A | B |
|---|
| extinct | A species that is gone forever. |
| territory | An area an animal defends from others. |
| death rate | The number of organisms that die during a given period of time. |
| birth rate | Number of organisms born during a given period of time. |
| succession | Series of changes that naturally takes place in a community over time. |
| habitat | The place where an organism lives. |
| population | All the organisms of one species that live in a certain place. |
| pioneer stage | The first stage of succession. |
| niche | The way a species lives. |
| community | All the populations in one ecosystem. |
| endangered species | A species in danger of disappearing from Earth because few are left. |
| ecology | Study of relationships among living and nonliving things. |
| climax community | The final stage of succession in a community. |
| ecosystem | A community and its nonliving environment. |
