Their modeling of a single‐resource system, however, assumed that prey species must compete for the same resource in order to exist, whereas Holt's (1977) model assumed the opposite. “Apparent competition” is a phrase that today largely refers to an indirect negative interaction between individuals, populations, species, or entire functional groups, medi- ated through the action of one or more species of shared natural enemies. Apparent competition is a situation in which it appears that two species compete for limited resources, because the presence of one reduces the abundance of the other. The model was able to predict the actual relative abundances of D. aurita and M. nudicaudatus in the three empirical studies analyzed. In order to study the consequences of predator-mediated apparent competition in isolation from other complicating factors, a model community is analyzed in which there is no direct interspecific competition … Another reason for being cautious in our discussion of competition is the existence of what Holt (1977, 1984) has called 'apparent competition', and what others have called 'competition for enemy-free space' (Jeffries & Lawton, 1984, 1985). In competition theory, resources are often, but not always, assumed to have very simple dynamics, and intra- and inter- Joseph H. Connell, Apparent versus “Real” Competition in Plants, Perspectives on Plant Competition, 10.1016/B978-0-12-294452-9.50006-0, (9-26), (1990). How-ever, the change in the mean density of one species. This effect of apparent competition has been recently demonstrated by experiments using a host–parasitoid system (Hassell and Bonsall). Our study presents quantitative support to the apparent competition theory; however, the model's applications to other groups still need to be verified. caused by a small change in the harvest rate of another. But, the question still remains whether the observed behavior is dependent upon the spatial structure of the model, or whether it could also happen in a non-spatial version. ent competition, and it is predicted that species will evolve to colonise enemy-free space (Jef-fries & Lawton 1984). Figures 2-8 follow. Imagine a single species of predator or parasite that attacks two species of prey (or host). described as apparent competition in this model. interpreted as apparent competition resulting from shared predation. The CAM-8 model illustrates the phenomenon of apparent competition in an explicitly spatial model. Parameters are defined in the text. The effect of a shared parasite on the dynamics between two host species has been investigated by mathematical models ( Hudson and Greenman, 1998 ; Greenman and Hudson 1999 , Greenman and Hudson 2000 ). See Apparent Competition and Biocontrol for the accompanying text. FIGURE 2: Transfer diagram for the three species model showing probabilities of moving from one state to another. 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