Many natural communities show nested subset patterns of species composition, in which small communities contain subsets of the species found in richer ones. A broad comparative survey of natural communities will be used to determine the generality of this nonrandom pattern and to identify the biotic and abiotic factors that produce it. The survey will include terrestrial and aquatic, temperate and tropical, plant and animal, and vertebrate and invertebrate systems. Several techniques for analyzing this type of community structure--one established by the PI and the others now in development by collaborating scientists--will be employed. Two of these techniques are based on Monte Carlo simulations, while the third involves explicit mathematical solutions. Funds are requested for: a personal computer and graduate assistant (0.5 year FTE) to conduct the analyses, and travel funds to enable the PI and three collaborators to meet at the beginning and conclusion of the project to "brainstorm" techniques, problems, and applications of the nested subset pattern. The breadth of the survey, the variety of analyses, and the different backgrounds of the PI and collaborators (spanning systematics, paleontology, soil ecology, and cybernetics) promise new, robust perspectives on the ecological importance of nested subset patterns.
