Algorithmic reconstruction of trophic networks from open-access species lists reveals key organisms in real ecosystems
Fig 8
Robustness to functional rarefactions.
Y-axes in panels A–C represent the absolute difference between each measured network attribute and the mean value of the corresponding attribute in the original (unperturbed) networks, expressed in units of the standard deviation of that attribute across replicates of the original networks. Accordingly, values close to zero indicate negligible differences, values around one indicate deviations comparable to the intrinsic variability of the original networks, and values greater than one indicate differences exceeding that variability. (A). The ecosystems’ structure is more deeply affected when herbivores are removed, while removing plants or carnivores has a milder effect. However, the removal of any trophic group has catastrophic effects on the network structure if >N/2 of species are removed (see Figs 7, S2 and panel (C)). (B). The ecosystems’ structure is deeply affected when medium-sized organisms are removed. As the four size intervals defined do not cover all (>12) orders of magnitude present in the whole dataset, the % of species removed (X-axis) never reaches the N/2 limit as in A. (D). A summary of the general trends shown in previous panels taking the average slope (A.S.) as a proxy of network change. Most topological attributes vary more intensely, and above a random rarefaction (C), when herbivores and/or medium-sized animals are removed. In (B-C), grey points correspond to individual (perturbed) replicates. Red dashed lines: linear regressions of the represented data (with slope A.S.).