Invasive Species and the Cultural Keystone Species Concept

Abstract

The concept of the keystone species (Paine 1966, 1969, Power et al. 1996) has been a transformative notion in ecology. Keystone species were originally narrowly defined to be those whose importance to community and ecosystem structure, composition, and function is disproportionate to their abundance. Even this narrow definition fostered great insight into the nature of particular ecosystems and of threats to them (Power et al. 1996). However, in ecological circles the term came to be more casually used to mean any species that has a very large impact on the ecosystem, no matter how abundant it is (Simberloff 2003), and this casual usage has led to attacks on the concept on the grounds that it is so vague that it is meaningless (e.g., Mills et al. 1993). The phrase has even been freely and loosely borrowed outside ecology; for example, it has migrated into business and economics (Iansiti and Levien 2004).