Node Degree Correlations in Evolved and Natural PDUG

(A) Shown is the Z score for the probability P(k1,k2) of the two nodes with degree k1,k2 being connected to each other in the natural PDUG. Unlike in other networks, nodes of similar degree tend to be connected.

(B) The Z score plot of P(k1,k2) for the structure similarity graph obtained in the evolution model is remarkably similar to the actual one.