Meeting Abstract
Color vision allows for increased discrimination of environmental stimuli, aiding organisms in identification of suitable resources amid complex backgrounds, navigation, and inter- and intraspecific visual communication. Different groups of organisms have evolved visual systems with different numbers of photoreceptor types, and with different peak sensitivities. While numerous studies have focused on the importance of photoreceptor sensitivities relative to ecological function, few have investigated why the number of photoreceptors varies between organismal groups. We quantitatively compared the discriminability of additional photoreceptor types to the discriminability available from simply adjusting photoreceptor peak sensitivities.
We used receptor-noise-limited models to generate discrimination landscapes for visual systems with different numbers of photoreceptor types, using spectral datasets from different ecosystems. We employed an adaptive walk procedure mimicking characteristics of photoreceptor sensitivity evolution, and we tracked the moves through these discriminability landscapes while modifying additional visual system parameters. We then analyzed whether gains in discriminability from the addition of photoreceptor types were greater than those achieved solely from photoreceptor tuning. Additionally, we compared discriminability landscapes between ecosystem-specific datasets to consider how landscape features may affect the evolutionary specifics of photoreceptor tuning.
