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SOE: Fachverband Physik sozio-ökonomischer Systeme
SOE 8: Networks, From Topology to Dynamics (joint session SOE/BP/DY)
SOE 8.3: Talk
Wednesday, March 19, 2025, 15:30–15:45, H45
Functional Motifs in Food Webs and Networks — •Melanie Habermann1, 2, 3, Ashkaan Fahimipour4, Justin Yeakel5, 6, and Thilo Gross1, 2, 3 — 1Helmholtz Institute for Functional Marine Biodiversity (HIFMB), Oldenburg, GER — 2Alfred-Wegener Institute (AWI), Helmholtz Center for Polar and Marine Research, Bremerhaven, GER — 3Carl-von-Ossietzky University, Institute for Chemistry and Biology of the Marine Environment (ICBM), Oldenburg, GER — 4Florida Atlantic University, Boca Raton, FL, USA — 5University of California Merced, Merced, CA, USA — 6The Santa Fe Institute, Santa Fe, NM, USA
It is interesting to ask when the presence of a small subgraph in a complex network is sufficient to impose constraints on system dynamics that are independent of the broader network structure. We refer to these subgraphs as functional motifs. A classic example can be found in ecology with the competitive exclusion motif in food webs, where two species compete for the same resource without regulation. The presence of this motif precludes any stable equilibrium for the entire system. However, examples of other motifs with similarly definitive implications for system stability are rare. But our usual notion of asymptotic stability is just one among many different concepts of stability. Another one, reactivity, captures a system's immediate response to small perturbations. In this talk, we explain why functional stability motifs are rare and show that every subgraph is a functional reactivity motif. This highlights reactivity as a promising concept for exploring a vast range of networked phenomena.
Keywords: motifs; reactivity; stability; complexity; dynamics