The population ecology of organizations
Hannan and Freeman characterize more organization theory as focused on adaption. Instead, they argue that organizations are largely inert, or can be treated as such. More problematically (and completely at odds with the fundamental observation of extreme organizational similarity at the heart of the institutionalist approach in DiMaggio and Powell's (1983) The iron cage revisited: Institutional isomorphism and collective rationality in organizational fields) they note that adaption -- and isomorphism in particular -- cannot explain the extreme variety of organizations.
Building on Stinchcombe (1965) they suggest that organizations are largely inert and detail a long enumerated list on constraints leading to inertia. They also argue external pressures can force inertia. They argue that a theory explaining variety in the face of inertia should be able should add selection at the level of a population of organizations (a concept they introduce and borrow from biology). They also suggest that there are communities which consist of multiple populations of organizations.
Populations of organizations find an analog, the authors argue, in species. Using this metaphor, they argue that it's possible to important some (but not all) of the tools developed for thinking about the selection of species and organizations within species.
Of course, organizations are not perfect analogs for organism. For example, human social organizations can learn and adapt more than many organism. Learning, the authors argue, is an important difference not included in most traditional ecological models. Similarly, they argue that organizations can expand to cover additional resources.
The authors also introduce what they call "niche" theory. Essentially, they argue that in uncertain and unstable environments, one will expect to see more generalist organizations, but that in stable and certain environments, one would expect to see more specialists. They argue that the "width" of a niche has important implications for understanding broad organizational strategies.
The paper offers no empirical evidence to support their theories, although a large amount of follow-on research will address a large number of the issues they raise in depth.
Theoretical and practical relevance:
The population ecology of organizations is the seminal article in the population ecology stream of organizational theory and is one of the major streams in contemporary organization theory. As such, it is one of the most highly cited and influential articles in organization theory.
The paper introduces a number of the key issues that will become the dominant features of that literature. For example, the in-depth discussion of niche-width already contains many of the core insights that upon which that sub-stream is built.