Where does population ecology collide?

The study of how whole populations of organizations of a given form arise, spread, and die out, where selection rather than individual adaptation decides which forms survive. Hannan and Freeman's 1977 paper The Population Ecology of Organizations argued that most organizations are too inert to change with their environments, so the mix of forms in a society is set mainly by differential founding and mortality across the population. Their 1984 paper Structural Inertia and Organizational Change made the inertia claim precise, treating reliability and accountability as the traits selection favours and the same traits that then resist change. Carroll and Hannan later showed that founding and mortality rates depend on the density of the population itself, rising and then falling as the number of organizations grows. The referent here is a research programme in organizational sociology and its account of firms and forms, not a claim about plants or animals.[1][2][3]

Unit

A population of organizations sharing a form, tracked by founding and mortality

Recovery means

Not applicable

Measured by

Event-history models of founding and failure rates against population density and age

In biology, population ecology is the branch that studies how the size and age structure of a population of a single species change over time and space. Its core ideas are density dependence, in which birth and death rates shift as a population becomes crowded, and a carrying capacity, the size an environment can sustain. Pearl and Reed's 1920 paper fitted the logistic growth curve to the population of the United States, one of the early empirical uses of a density-limited growth model for a real population. The objects of study are living organisms counted in a habitat, and the questions are about regulation, growth, and persistence in nature. This is a field within the life sciences, with its own data and methods, and it long predates the borrowing of its vocabulary by students of organizations.[4]

Unit

A population of one species in a habitat, counted over time

Recovery means

A population below carrying capacity tends to grow back toward it, as density-dependent rates ease

Measured by

Census and mark-recapture counts, fitted to growth and density-dependence models

A family of mathematical models that describe how population sizes change, used across ecology, demography, and epidemiology. The logistic equation gives density-limited growth toward a carrying capacity; the Lotka-Volterra equations, which Volterra set out in 1926, describe the coupled rise and fall of predator and prey numbers. Levins's 1969 work introduced the metapopulation idea, a population of local populations linked by migration, where patches wink out and are recolonised. These are formal objects, systems of equations whose behaviour can be analysed on their own terms, apart from any particular species. They supply the shared quantitative language that both biological and organizational ecologists have drawn on, which is part of why the same words travel between the two.[5][6]

Unit

A system of equations for population size over time

Recovery means

In the logistic model a population returns toward its carrying capacity after a disturbance

Measured by

Analysed mathematically and fitted to time series of counts by parameter estimation