Ecology is the study of living beings relationships to the world around them, including other living beings.
Ecology is the study of the interdependence of living beings.
Ecology is the branch of biology that deals with organisms' relations to one another and to the physical environment in which they live.
Ecology is the study of such relations as they pertain to a particular habitat or a particular species.
Human ecology the branch of knowledge that deals with the interaction of humans with their environment.
The Green Parties or Greens are political movements that seeks to protect the environment, esp. from pollution.
Ecology also refers to the political movement that seeks to protect the environment, especially from pollution.