An inherited behavior or physical characteristic that helps an organism survive and reproduce in its environment.

The ability of an ecosystem to maintain biodiversity and production indefinitely.

An interaction in which one organism kills another for food or nutrients.

The community of organisms that live in a particular area, along with their nonliving environment.

a fact or situation that is observed to exist or happen, especially one whose cause or explanation is in question.

Something found in nature that enhances the lives of plants, animals, and humans.

the average number of organisms per unit of area.

Features that help to identify something.

A function played by a person or thing in a particular situation.