Ecosystem
The term ecosystem was first used in 1935 in a publication by British ecologist Arthur Tansley. Tansley devised the concept to draw attention to the importance of transfers of materials between organisms and their environment. He later refined the term, describing it as "The whole system, ... including not only the organism-complex, but also the whole complex of physical factors forming what we call the environment". Tansley regarded ecosystems not simply as natural units, but as "mental isolates". Tansley later defined the spatial extent of ecosystems using the term ecotope.
Organizational ecology
The first explicit formulation of a theory of population ecology, by Michael T. Hannan and the late John H. Freeman in their 1977 "American Journal of Sociology" piece "The population ecology of organizations" and later refined in their 1989 book "Organizational Ecology", examines the environment in which organizations compete and how a process like natural selection occurs. This theory looks at the death of organizations (firm mortality), the birth of new organizations (organizational founding), as well as organizational growth and change.