Biosimplicity via stoichiometry: the evolution of food-web structure and processes

Food webs are among the most complex entities under study in modern biology. But what if major features of their structure and dynamics were the product of a relatively few simple rules? This chapter describes perspectives arising from the field of biological stoichiometry to argue that major features of food web function in ecosystems are the outcome of a relatively straightforward combination of chemical principles (mass balance, stoichiometric combination) of entities experiencing the Darwinian selective algorithm. It argues that the fate of energy or carbon in food webs, to a major extent, is governed by the availability and packaging of key nutrients like nitrogen and phosphorus. Indeed, phenomena such as transfer efficiency, length of food chains, community composition, degree of omnivory, and the relative importance of grazing versus detrital pathways all appear to have a strong stoichiometric component and the underlying rules generating these phenomena involve fundamental evolutionary trade-offs and coevolutionary dynamics.