Fig. 9
From: In silico evo-devo: reconstructing stages in the evolution of animal segmentation
Mechanisms to stop growing differ in phenotypic variability (persistent signal, no CCS). a, b Individuals capable of sequential segmentation that are subsequently subjected to a pressure to stop growing. a This individual stops growing by increasing the expression of gene 1 over time. Note the addition of the extra module for stopping growth in the network. b This individual stops growing because gene 5 stochastically passes a threshold, above which its expression stabilises and switches off the division gene. c The individual of a maintains its developmental robustness (left histogram) and the one in b does not (right histogram). Both had very low phenotypic variation before the addition of the extra selection pressure, looking like the left histogram