Fluctuating environments reveal principles of rapid structural adaptability

In biological contexts, selection in changing environments can localize molecules to regions of sequence space where rapid adaptability between multiple structures is possible. This leaves an open question: what principles allow those regions of rapid adaptability to exist to begin with? By evolving a diverse set of physical systems (disordered elastic networks, heteropolymers with tunable interactions), we show that fluctuating environments naturally identify a minimal set of interactions which can be rewired to generate rapid adaptability. In the particular context of biomolecular folding (proteins, RNA), we further show that the frequency of adaptable paths between folds increases as the correlation between folding interactions drops.