Generalized Selected Effects Functions and Ecology

Expanding upon the “classical” selected effects (SE) theory of function, Justin Garson’s generalized selected effects (GSE) theory states that functions may derive not just from natural selection, but from a broader range of selection processes involving differential retention as well as reproduction. In this paper, we consider whether the GSE theory’s broadened range of selection processes makes it more promisingly applicable to ecology than the classical SE theory. We argue that, although a GSE account of ecological role functions would evade some of the reasons that the SE theory of function has been considered poorly applicable to ecology, alternative theories of function, and notably the persistence enhancing propensity (PEP) account of ecological role functions, remain more appropriate partly given the purpose for which the concept of role function is used in ecology. The GSE theory’s backward-looking character meshes poorly with the fact that, in ecology, the concept of role function is used mainly to explain how ecosystems are able to achieve their processes reliably rather than to explain the presence of certain ecological items (e.g., organisms, populations, species) within them. We argue this in part by comparing the implications of a GSE account of ecological role functions with those of the PEP account with respect to three types of cases: dormant species, sink populations, and abiotic items. We draw out implications of our discussion for Garson’s take on function pluralism and his overall defense of the GSE theory.