Figure 1

Panel (a) Comparison of three simple networks containing the same number of species (nodes) and trophic links (lines). In network 1, all species are part of one food chain, and a disturbance originating from any given species would directly propagate along the food chain to all the remaining ones. In network 2, a bottom-up disturbance spreading from species 1 would affect species 4-5-6 only. In network 3, the modification of a single link with respect to network 2 would mean that only species 4 would be directly affected by a bottom-up disturbance propagating from species 1. Panels (b–d) Food sub-webs exemplifying various propagation pathways along food chains for disturbance starting from a single species (circled): (b) bottom-up propagation from a basal resource (red), (c) cross propagation from a primary consumer (orange), and (d) top-down propagation from a predator (yellow).