One or more light sources may apply stimuli to a colony of organisms. The stimuli may include visible and non-visible light. The stimuli, taken together, may tend to favor survival of organisms that are adapted to perform photosynthesis which involves absorbing energy from infrared or ultraviolet light. In some cases, the set of stimuli may include illuminating the entire colony of organisms with green light, illuminating only a first portion of the colony with pulsed ultraviolet light, and illuminating only a second portion of the colony with pulsed infrared light.