Interactive effects of body‐size structure and adaptive foraging on food‐web stability

Abstract

Body-size structure of food webs and adaptive foraging of consumers are two of the dominant concepts of our understanding how natural ecosystems maintain their stability and diversity. The interplay of these two processes, however, is a critically important yet unresolved issue. To fill this gap in our knowledge of ecosystem stability, we investigate dynamic random and niche model food webs to evaluate the proportion of persistent species. We show that stronger body-size structures and faster adaptation stabilise these food webs. Body-size structures yield stabilising configurations of interaction strength distributions across food webs, and adaptive foraging emphasises links to resources closer to the base. Moreover, both mechanisms combined have a cumulative effect. Most importantly, unstructured random webs evolve via adaptive foraging into stable size-structured food webs. This offers a mechanistic explanation of how size structure adaptively emerges in complex food webs, thus building a novel bridge between these two important stabilising mechanisms.

Climate change in size-structured ecosystems

“…Prey of vertebrate species migrating in altitude are larger than prey species already inhabiting this area, whereas predators that expand their ranges in altitude are not different in size than the natives [21]. This leads to decreases in predator-prey body-size ratios, which have similar implications for the community size structure as the loss of large species, and this is ultimately likely to affect community dynamics [61,68,75].…”

“…decreasing the likelihood that dynamics lead to extinctions) [61,[68][69][70], preventing competitive exclusion processes among basal species such as plants [69], and buffering against unstable enrichment effects [71] and secondary extinctions waves [72]. However, the question of how warming interacts with size structure has been relatively unexplored.…”

Unifying ecological stoichiometry and metabolic theory to predict production and trophic transfer in a marine planktonic food web

“…In this context, body size and temperature are generally identified as important determinants of species interactions (e.g. [18]) and community level dynamics and stability [19].…”

Prohibition rules for three-node substructures in ordered food webs with cannibalistic species

“…Due to the allometric relationship between body mass and metabolic rates (Brown et al 2004), the dynamics of interacting populations depends on their relative niche positions (i.e., predatorÀ-prey body-mass ratios, Yodzis and Innes 1992) and stable configurations that allow for the persistence of all species are usually found if predators are larger than their prey (Otto et al 2007;Kartascheff et al 2010;Heckmann et al 2012). Most of the three-node substructures that are prohibited by the niche model include links between a small predator and a large prey, and our results suggest that these substructures are more common in natural food webs than previously assumed.…”