HISTORY AND CURRENT DEVELOPMENT OF A PARADIGM OF PREDATION IN ROCKY INTERTIDAL COMMUNITIES

A paradigm is a set of mutually supportive hypotheses that provides a frame of reference within a field. In 1962, Kuhn proposed that paradigms form within the dual contexts of empirical evidence and intellectual history. Facts potentially contradictory to a paradigm may not be recognized until they are observed repeatedly and incorporated as supportive evidence into a new theory. Support for this interpretation can be found in the history of a paradigm of predation in rocky intertidal communities. Hypotheses were developed in the contexts of innovative field experiments and historical arguments of competition theory. The resulting paradigm proposed that predators restrict populations of competitively dominant prey to refuges. Different types of refuge, or no refuge, prevail in different areas of the intertidal zone, accounting for patterns of prey distribution, the coexistence of natural enemies, and the local maintenance of diversity. An ensuing period of criticism made reference to potential contradictions. Rather than by predation alone, prey abundances are determined largely by an interplay of varying rates of predation and prey production. Furthermore, prey refuges are neither necessary nor sufficient to explain all observed instances of local coexistence of predators and prey. We present a model in which intertidal boundaries of prey are set by equilibria between predation and prey production. Predation and prey productivity vary with environmental gradients and with explicit spatial configurations of the prey. This synthesis relies on insights of the original paradigm, incorporates the contradictory observations, and depends on novel capabilities afforded by spatially explicit computer simulations. The resulting synthesis provides explanations for distinctive aspects of zonation, including abrupt prey boundaries in continuous gradients of predation, and converging upper and lower prey boundaries in gradients of decreasing wave exposure.