The Ecology of Mutualism

Abstract

Elementary ecology texts tell us that organisms interact in three fundamental ways, generally given names competition, predation, and mutualism. The third member has gotten short shrift (264), and even its name is 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. We use term mutualism, defined as an interaction between species that is beneficial to both, since it has both historical priority (311) and general currency. Symbiosis is the living together of two organisms in close association, and modifiers are used to specify dependence on interaction (facultative or obligate) and range of species that can take part (oligophilic or polyphilic). We make normal apologies concerning forcing continuous variation and diverse interactions into simple dichotomous classifications, for these and all subsequent definitions. Thus mutualism can be defined, in brief, as a -b/qinteraction, while competition, predation, and eommensalism are respectively -/-, -/q-, and -t-/0. There remains, however, question of how to define benefit to