Fig. 6.

Fraction of appearances of motifs for empirical food webs (symbols) compared to the analytical predictions for the generalized cascade model (solid lines) and the random model (dashed lines). Numerical simulations for the generalized cascade model with S = 50 are shown by the dotted line where the error bars are two standard deviations. It is visually apparent that the generalized cascade model fits rather well the empirical data for all the motifs, whereas the random model provides much poorer fits. Note that there are no fitting parameters in model estimates.