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. 2016 Jun 9;12(6):e1004829. doi: 10.1371/journal.pcbi.1004829

Fig 6. Evolving low-cost, high-performing networks that are non-modular reveals that independent of modularity, a connection cost promotes the evolution of hierarchy.

Fig 6

(A) Networks from the 16 highest-performing P&CC-NonMod replicates (S4 Fig shows networks from all 30 trials). The networks are hierarchal, but not highly modular. (B) There is no significant difference in modularity between P&CC-NonMod and PA networks, but P&CC-NonMod networks are significantly more hierarchical (C) and solve significantly more sub-problems (D) than PA networks. (E-G) P&CC-NonMod networks also adapt significantly faster to a new environment than PA networks, suggesting that hierarchy promotes evolvability independently of modularity. (E) The base and target problem for this evolvability experiment. (F) A perfect-performing network evolved for the base problem (left) and a descendant network evolved on the target problem (right). The example networks are those with median hierarchy: S11 Fig shows all pairs. (G) P&CC-NonMod networks adapt significantly faster to the new problem.