Structural correlations among reaction nodes with the same organism degree (OD). The curves show the two-node correlation function which captures the likelihood of finding two reactions of the same OD k steps apart from each other. The blue curve is based on the actual data while the green curve shows the correlation function when the OD attribute of all reaction nodes is randomly reshuffled.
Bernhardsson et al. BMC Evolutionary Biology 2011 11:20 doi:10.1186/1471-2148-11-20