The Niche Concept

The Niche Concept Revisited: Mechanistic Models and Community Context Matthew A. Leibold Ecology, Vol. 76, No. 5. (Jul., 1995), pp. 1371-1382.
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Editor's Note
Ecology's love-hate relationship with the niche concept has been long and not especially pretty. Whereas some ecologists continue to see value in the concept, others have despaired of ever finding an expression that is both general and noncircular. Part of the problem, originatingearly in our science, has been that different investigators have meant different things by "niche." Here, Leibold uses resourcebased competition theory to produce a single construct that accommodates the earlier differences in meaning, while at the same time permitting measurement and experimentation. Although attempts to define the niche of a species may still prove fruitless, Leibold's contributionis to suggest that it is nevertheless possible to delineate niche parameters relevant to a variety of ecological interactions. Nelson G. Hairson, Jr.

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Ecology, 76(5), 1995. pp. 1371-1382 0 1995 by the Ecological Society of America

THE NICHE CONCEPT REVISITED:
MECHANISTIC MODELS AND COMMUNITY CONTEXT1

Mathew A.Leibold Department of Ecology and Evolution University of Chicago, 1101 E. 57th Street Chicago, Illinois 60637 USA

Abstract
The niche concept is a central organizing aspect of modern ecology. Although its history has often been reviewed, the structure of the concept and its connection to advances in ecological theory has received less recent attention. I review the niche concept using"mechanistic" models of community theory to identify two distinct components. One describes the environmental requirements of organisms and the other describes the per capita impact of organisms on the environment. I argue that these correspond to significant differences between Grinnell's and Elton's concepts distinct from the previously discussed "habitat" vs. "functional" dichotomy. I illustrate thedistinction between the requirement and impact components of the niche using models of resource competition and of keystone predators, and I discuss "Gause's axiom" and conventional "niche theory" in the context of these two distinct niche components. I suggest that the niche concept be elucidated by explicit reference to these two distinct components; the "impact" niche (corresponding to Elton'sconcept) describing instantaneous per-capita effects of species on the environment, and the "requirement" niche describing the response of species to the environment (corresponding to Hutchinson's definition). This approach connects conventional niche theory with "mechanistic" individualbased ecological models and can help provide a more modern context for the niche concept.
Key words: competition;...