  We study genetic networks that produce many species of non-coding RNA
molecules that are present at a moderate density, as typically exists in the
cell. The associations of the many species of these RNA are modeled physically,
taking into account the equilibrium constants between bound and unbound states.
By including the pair-wise binding of the many RNA species, the network becomes
highly interconnected and shows different properties than the usual type of
genetic network. It shows much more robustness to mutation, and also rapid
evolutionary adaptation in an environment that oscillates in time. This
provides a possible explanation for the weak evolutionary constraints seen in
much of the non-coding RNA that has been studied.
