Simplicity on the other side of ecological complexity

Darwin's classic image of a 'tangled bank' of interdependencies among species has long suggested the difficulty of predicting how the loss of one species alters the abundance of others 1. We show that for dynamical models of realistically structured ecological networks in which pair-wise consumer-resource interactions scale according to allometric ¾ power rules suggested by metabolic theory 2,3 , the effect of losing one species on another typically can be predicted surprisingly well by simple functions of variables that can be observed in nature. By systematically removing individual species from 600 10-30 species networks, we analyzed how the sign and magnitude of 254,032 possible pair-wise species interactions depended on 90 stochastically varied species, link, and network attributes. Population-level and