The Ecology of Mutualism
Annual Reviews www.annualreviews.org/aronline AngRev. Ecol. Syst. 1982.13:315--47 Copyright©1982 by Annual Reviews lnc. All rightsreserved THE ECOLOGY OF MUTUALISM Douglas 1t. Boucher Departementdes sciences biologiques, Universit~ du Quebec~ Montreal, C. P. 8888, Suet. A, Montreal, Quebec, CanadaH3C 3P8 Sam James Departmentof Ecologyand Evolutionary Biology, University of Michigan, Ann Arbor, Michigan, USA48109 Kathleen H. Keeler School of Life Sciences, University of Nebraska,Lincoln, Nebraska,USA 68588 INTRODUCTION Elementaryecology texts tell us that organismsinteract in three fundamen- tal ways, generally given the namescompetition, predation, and mutualism. The third memberhas gotten short shrift (264), and even its nameis not generally agreed on. Terms that may be considered synonyms,in whole or part, are symbiosis, commensalism,cooperation, protocooperation, mutual aid, facilitation, reciprocal altruism, and entraide. Weuse the term mutual- by University of Kanas-Lawrence & Edwards on 09/26/05. For personal use only. ism, defined as "an interaction betweenspecies that is beneficial to both," Annu. Rev. Ecol. Syst. 1982.13:315-347. Downloaded from arjournals.annualreviews.org since it has both historical priority (311) and general currency. Symbiosis is "the living together of two organismsin close association," and modifiers are used to specify dependenceon the interaction (facultative or obligate) and the range of species that can take part (oligophilic or polyphilic). We make the normal apologies concerning forcing continuous variation and diverse interactions into simple dichotomousclassifications, for these and all subsequentdefinitions. Thus mutualism can be defined, in brief, as a -b/q- interaction, while competition, predation, and eommensalismare respectively -/-, -/q-, and -t-/0. There remains, however,the question of howto define "benefit to the 315 0066-4162/82/1120-0315 $02.00 Annual Reviews www.annualreviews.org/aronline 316 BOUCHER, JAMES & KEELER species" without evoking group selection.
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