Before revision: We show the following properties for the GRNs in the "fittest ensemble" : (1) They distinguish two different states of the input by switching the fixed points .
After revision: We show the following properties for the GRNs in the "fittest ensemble" : (1) Highly-fit GRNs exhibited bistability for intermediate input between "on" and "off". This means that such GRNs responded to two input states by using different fixed points of dynamics. This bistability emerges necessarily as fitness increases .