title: Linking structure and function in food webs: maximization of different ecological functions generates distinct food web structures.
abstract: Trophic interactions are central to ecosystem functioning, but the link between food web structure and ecosystem functioning remains obscure. Regularities (i.e. consistent patterns) in food web structure suggest the possibility of regularities in ecosystem functioning, which might be used to relate structure to function. We introduce a novel, genetic algorithm approach to simulate food webs with maximized throughput (a proxy for ecosystem functioning) and compare the structure of these simulated food webs to real empirical food webs using common metrics of food web structure. We repeat this analysis using robustness to secondary extinctions (a proxy for ecosystem resilience) instead of throughput to determine the relative contributions of ecosystem functioning and ecosystem resilience to food web structure. Simulated food webs that maximized robustness were similar to real food webs when connectance (i.e. levels of interaction across the food web) was high, but this result did not extend to food webs with low connectance. Simulated food webs that maximized throughput or a combination of throughput and robustness were not similar to any real food webs. Simulated maximum-throughput food webs differed markedly from maximum-robustness food webs, which suggests that maximizing different ecological functions can generate distinct food web structures. Based on our results, food web structure would appear to have a stronger relationship with ecosystem resilience than with ecosystem throughput. Our genetic algorithm approach is general and is well suited to large, realistically complex food webs. Genetic algorithms can incorporate constraints on structure and can generate outputs that can be compared directly to empirical data. Our method can be used to explore a range of maximization or minimization hypotheses, providing new perspectives on the links between structure and function in ecological systems.
authors.affiliation: School of Physics and Astronomy, Monash University, Melbourne, VIC, 3800, Australia.
authors.forename: Jian D L
authors.initials: JD
authors.lastname: Yen
authors.affiliation: National Institute of Physics, University of the Philippines Diliman, Quezon City, 1101, Philippines.
authors.forename: Reniel B
authors.initials: RB
authors.lastname: Cabral
authors.affiliation: Department of Biology, Dalhousie University, B3H 4J1, Halifax, Canada.
authors.forename: Mauricio
authors.initials: M
authors.lastname: Cantor
authors.affiliation: Department of Biology, McGill University, H3A 1B1, Montreal, Canada.
authors.forename: Ian
authors.initials: I
authors.lastname: Hatton
authors.affiliation: Norwegian College of Fishery Science, UIT the Arctic University of Norway, 9037, Tromsø, Norway.
authors.forename: Susanne
authors.initials: S
authors.lastname: Kortsch
authors.affiliation: European Commission, Joint Research Centre, Institute for Environment and Sustainability, 21027, Ispra, Italy.
authors.forename: Joana
authors.initials: J
authors.lastname: Patrício
authors.affiliation: Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY, 14853-2701, USA.
authors.forename: Masato
authors.initials: M
authors.lastname: Yamamichi
mesh_terms: D000818:Animals; D020387:Food Chain; D008954:Models, Biological
keywords: biodiversity; ecological networks; ecosystem functioning; ecosystem resilience; genetic algorithm; secondary extinctions; total system throughput; trophic interactions