Predator-Mediated Coexistence: A Nonequilibrium Model

摘要: trophic level, explanations for coexistence are usually framed in terms of competition by asking what properties the species, and their environment, prevent from excluding some members assemblage. Predation, impinging on a group (presumably) competing has been implicated as potentially important factor which might allow coexistence. Observations such "predator-mediated coexistence" now commonplace, including Darwin (1859) mowing grassland plants, Summerhayes (1941) voles Paine (1966, 1971) Dayton (1971) starfish intertidal invertebrates, Harper (1969) grazers Slobodkin (1964) harvesting laboratory hydrids, Neill (1972) fish zooplankton, Porter corals. Brooks Dodson (1965), Wells (1970), Hall et al. (1970) showed that predation could mediate zooplankton coexistence, although it is not certain interaction being affected purely competitive (Dodson 1974). Finally, also shown to contribute different genetic morphs within single e.g., (Zaret 1972) moths (Kettlewell 1955; Lees Creed 1975). There studies have failed demonstrate predator-mediated or actually decrease number coexisting species under impact (e.g., 1969; Vadas Hurlbert 1972; Adicott 1974; Janzen 1976). These particularly useful tests any theory devised explain Not only must be able generate observed positive effect but should conditions seen negative. The empirical observations led naturally suggestion may play major role structuring communities (Paine 1966; 1970; Connell 1970) thus attempts incorporate into mathematical framework population biology. date frustrating. While possibility predatormediated demonstrated, most analyses make its occur