Variation in Niche Breadth with Trophic Position: On the Disparity between Expected and Observed Species Packing

The observation that more kinds of predators than prey comprise natural communities is more likely an artifact of systematic variation in the kinds of organisms that biologists distinguish at different trophic levels than a fact of nature. The opposite expectation is derived from a dynamic theory of community development. We should gather observations from which we can determine the numbers of trophic resources at different levels in natural communities without further delay. In that endeavor, objective methods, such as Vandermeer's (1972) grain matrix, should prove particularly useful.