Aldo Leopold wrote that habitat conservation requires that we save 'every cog and wheel' (Leopold, 1949). The basis for his statement is that species interact in ways both positive and negative, direct and indirect. When interactions are strong, lossof one species may affect abundance of other species in the community (e.g. Paine, 1966; Terborgh, 1986). Diffuse interactions, although much less strong, may also affect species' abundances and distributions. Seed dispersal by animals is an example ofa diffuse interaction, because many animals typically disperse the seeds of a given plant species (e.g. McDiarmid et al., 1977; Lambert, 1989). It is also an important mutualism, especially in tropical wet forests (Gentry, 1982). In this chapter we explore the potential consequences to plants of losing one or more seeddispersers from the community in a system characterized by diffuse interactions between fleshy-fruited plants and fruit-eating birds.
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