A term invented by Ernst H. Haeckel (1834-1919) in 1866 and which now denotes the interdisciplinary study of the relationships among organisms and their environments, including both living and non-living components. It addresses three levels of organisation: the individual, the population and community levels.
See Community, Ecological psychology, Ecological systems theory, Ecosystem, Environment, Habitat (ecology), Levels of organization, Niche (ecology), Population (statistics)