What is Population Ecology? 

Population ecology is the study of dynamic changes (beginning, end, organizational forms) within a given set of organizations. 

Adaptation vs Selection

Hannan & Freeman (1989) believe that long-term change in the diversity of organizational forms within a population occurs through selection rather than adaptation. Most organizations have structural inertia that hinders adaptation when the environment changes. Those organizations that become incompatible with the environment are eventually replaced through competition with new organizations better suited to external demands .

Population ecologists ascribe to an evolutionary view of organizational change. Organizations descend from previous or existing organizations, and population-level change in organizational forms is usually slow and continual. Optimized change often depends on the "coupling" between intent and outcome.

The Demography and Ecology of Organizations

"Ecological analysis is appropriate when organizations are subject to strong inertial pressures and face changeable, uncertain environments." 

"(Population ecology) pays considerable attention to population dynamics, especially the processes of competition among diverse organizations for limited resources such as membership, capital, and legitimacy."

The first level, demography of organizations, concerns the variations in vital rates for organizational populations (founding rates, merger rates, disbanding rates, etc.). The model attempts to relate these changes to the environment.

The second level, population ecology of organizations, tries to show how the vital rates of one population are affected by other organizational populations.

The third level is community ecology of organizations. This looks as interacting communities of populations (like firms, labor unions, and regulatory agencies).