The role of theoretical ecology in the description and understanding of populations in heterogeneous environments

The role and function of theoretical ecology are examined. The case is made that theory must be recognized as an activity closely tied to, but separate and independent in objectives and perspective, from field observation and experimentation. Too literal interpretation of models, and rigid insistence on immediate congruence between theory and observation, have led to abuses and distortion of the role of theory. Examples are given to illustrate the partnership between theory and experiment, with emphasis on the partitioning and exploitation of space. The role of theory in guiding understanding and experimentation in the rocky intertidal community of the West Coast (Paine and Levin, 1981) is discussed. Models of individual movement based on random walk assumptions are summarized, with special attention to recent work by Kareiva (1982a, b, c) designed to test the applicability of diffusion models. Such models are shown to provide an excellent foundation for the study of the foraging movements of phytophagous insects: Extensions hold great promise as descriptors of movement for much wider classes of organisms and in the presence of complications such as taxis, grouping behavior, etc. Finally, some brief discussion is given on recent efforts to develop a theory of the evolution of dispersal and dormancy in heterogeneous environments.