  Light-harvesting bacteria Rhodospirillum Photometricum were recently found to
adopt strikingly different architectures depending on illumination conditions.
We present analytic and numerical calculations which explain this observation
by quantifying a dynamical interplay between excitation transfer kinetics and
reaction center cycling. High light-intensity membranes (HLIM) exploit
dissipation as a photo-protective mechanism, thereby safeguarding a steady
supply of chemical energy, while low light-intensity membranes (LLIM)
efficiently process unused illumination intensity by channelling it to open
reaction centers. More generally, our analysis elucidates and quantifies the
trade-offs in natural network design for solar energy conversion.
