Generalized Models Reveal Stabilizing Factors in Food Webs
Thilo Gross,*,1
Lars Rudolf,1
Simon A. Levin,2,3
Ulf Dieckmann4
Insights into what stabilizes natural food webs have always
been limited by a fundamental dilemma: Studies either need to
make unwarranted simplifying assumptions, which undermines their
relevance, or only examine few replicates of small food webs,
which hampers the robustness of findings. We used generalized
modeling to study several billion replicates of food webs with
nonlinear interactions and up to 50 species. In this way, first
we show that higher variability in link strengths stabilizes
food webs only when webs are relatively small, whereas larger
webs are instead destabilized. Second, we reveal a new power
law describing how food-web stability scales with the number
of species and their connectance. Third, we report two universal
rules: Food-web stability is enhanced when (i) species at a
high trophic level feed on multiple prey species and (ii) species
at an intermediate trophic level are fed upon by multiple predator
species.
2 Department of Ecology and Evolutionary Biology and Center for BioComplexity, Princeton University, Princeton, NJ 08540, USA.
3 University Fellow, Resources for the Future, 1616 P Street NW, Washington, DC 20036, USA.
4 Evolution and Ecology Program, International Institute for Applied Systems Analysis, Schlossplatz 1, 2361 Laxenburg, Austria.
* To whom correspondence should be addressed. E-mail: thilo.gross{at}physics.org
