Figure 1.

A run with parameter values s = 100, p = 0.005, and x₀ = 10⁻⁴. (a) Number of populated species, s₁, in the attractor of Eq. 1 (i.e., number of nodes with X_i > 0) after the nth addition of a new species (i.e., after n graph update time steps). (b) The number, l₊, of positive links (c_ij > 0) in the graph (blue); the number, l₋, of negative links (green); and “interdependency,” d̄, of the species in the network (red). The curves have three distinct regions. Initially s₁ is small; most of the species have zero relative populations. l₊ and l₋ also do not vary much from their initial (random graph) value (≈ps²/2 = 25) and remain approximately equal. d̄ hovers about its initial low value. In the second region s₁, l₊ and d̄ show a sharp increase, and l₋ decreases. In the third region s₁, l₊ and d̄ level off (but with fluctuations), and almost all species have nonzero populations in contrast to the initial period.