Fig. 4

Control profiles change with network size in observed avian networks, but not in their randomized counterparts. a, b Growth of avian networks does not require changes in proportion of controlling nodes (Nc/N). Instead different nodes acquire control status as a network grows, leading to changes in control profiles. c, d Randomized counterparts of observed avian networks. ER randomization reveals that growth of avian networks avoids elongation of existing biochemical pathways—producing a sharply decreasing proportion of Nc and the preservation of control profiles across a ten-fold increase in network sizes. Enzymatic pathway length (in reactions) is the longest minimal pathway between a dietary carotenoid and a terminal derived carotenoid deposited in plumage, averaged across pathways. Number of species in each group is given above bars