What Causes Variation in Peacock Feather Colors?

Sexual selection favoring the most attractive peafowl is very well understood, but the answer to what drives the variation in peacock feather coloration remains a mystery. The goal of this experiment is to determine the precise physical mechanism used by peafowl to generate such elaborate color variations in the eyespots of their tail feathers among males within the species. Barbs from eyespots of Pavo cristatus were embedded in an epoxy resin, sectioned on a microtome, and TEM images of the nanostructure within each barbule were analyzed. Results indicate that melanosome diameter is a significant positive predictor of iridescence and that as melanosome diameter increases and spacing decreases, brightness will increase. Variation in melanosome size does not predict physiological superiority among peafowl, but because melanin production is established genetically, females choosing to mate with more iridescent males may receive an additional benefit of a higher quality mate