Dynamical stability and complextopologies: patterns and mechanisms in food webs

Abstract

Food-web theory evaluates feeding relations between species, and has been recognized as one of the fundamental principals in ecology. However, in order to account for the complexity in which these interactions occur in natural communities, studies either emphasizes topological aspects of food-webs, or the mechanisms for stability of population dynamics. Furthermore, collecting high-quality food-web data involves extensive field works, while the consistency of the final data is conditioned to the objectives of the study, species identification and methods for inferring interactions. Thus, studies usually design theoretical models for the feeding behavior of consumers, in order to generate enough data for theoretical analyses. This work aimed to assess patterns and mechanisms of food webs, specifically the relationship between the complexity of natural communities, and their stability to endure perturbations. In general, the analyses combined theory and practice, using dynamical stability, probabilistic models, statistical inferences, and empirical data. Specifically, this work evaluated the causal relationship between the occurrence of dynamically stable modules (components of th food-web resilient to small perturbations) and statistical patterns of food-web topology. This work also evaluated the ability of food-web models to reproduce observable patterns of association between the feeding behavior of consumers and resources traits. The results suggest that dynamical stability of three and fourspecies modules allows the occurrence of complex food-web topology. This stability, however, is conditioned to a hurdleeffect, which favors the probability and frequency of occurrence of modules with higher expected stability. Further, the causal relationship between dynamics and topology occurs through these stable modules, which allow the occurrence of observable topological patterns. Finally, the results contribute to the understanding of the adequacy of inferences under theoretical models to empirical patterns, and the ability of models that assume few dimensions of the niche space to reproduce the complex matching patterns between predators feeding behavior with their resources traits.