COMMUNITIES
No living organism exists entirely by itself. It is always profoundly influenced by its environment. The branch of biology that studies the relationships between living organisms and their environments is known as ecology. Ecologists concentrate much of their study on communities and ecosystems. A community is defined as all of the organisms living in a given area and interacting with one another. An ecosystem is a community plus all of the nonliving components of its environment. This plate shows some of the components of a typical biological community and their relationships.