Classical food-web theory seeks to explain food-web structure with a focus on patterns and processes at small spatial and temporal scales. But real food webs are also the result of ecological and evolutionary processes at large spatial and temporal scales. Here I present a synthesis of new theoretical work on the emergence of complex food webs from simple rules operating at the individual or population level, using models that describe either evolutionary dynamics at long time scales or metacommunity dynamics at large spatial scales.
Results/Conclusions
A robust conclusion from these models is that complex food webs emerge spontaneously at large spatial and temporal scales despite simple rules that strongly constrain their structure and diversity at small scales. Evolutionary dynamics starting from a single ancestor species easily generates a rich array of species and trophic levels that mimics real food webs. Spatial metacommunity dynamics in systems that preclude local coexistence generates complex, diverse food webs at intermediate rates of dispersal despite a collapse in species diversity and food-web complexity at both low and high rates of dispersal. Furthermore, metacommunity dynamics leaves specific scale-dependent signatures in food-web structure that could be used to detect its operation in empirical data. These recent theoretical advances emphasize the importance of studying food webs in a historical and regional context.