Food Web Architecture and Population Dynamics: Theory and Empirical Evidence

Food web theory makes quantitative and qualitative predictions about the patterns of population dynamics to be expected in food webs with particular structures. Some of these predictions can be tested by comparing population dynamics in simple food chains of different architecture. Few studies have been designed specifically to manipulate food chain properties as a test of food web theory, but relevant information can be gleaned from studies of predatorprey dynamics in which food chain structure is known to vary in important ways. For example, comparisons of prey population dynamics in the presence or absence of a predator can be used to infer the consequences of a small change in food chain length. Common consequences of increased food chain length include greater temporal variation in abundance and a greater frequency of local extinctions. Studies that compare the impact of omnivore and nonomnivore predators are so infrequent that few conclusions can be reached. Ex