Birds are a group known for their wide variety of beautiful colors, from discreet browns and blacks in sparrows and partridges, to vibrant reds and yellows in canaries and parrots. However, shades of blue, and even iridescence, result from the optical and physical effects of light refraction in melanin (brown and black), giving rise to what is known as structural color. Depending on the complexity of the melanin organization, the structural color can vary from the strong blues of kingfishers to the most iridescence of hummingbirds. The domestication of peacocks has led to the appearance of more than a dozen color variants. By analyzing the genomes of these mutants, this project aimed to integrate molecular, optical and physical processes to explain the extraordinary variation in structural color and iridescence in birds. We found that, with small changes to melanin production, in the melanosome biogenesis and maturation, or in their transport to the feather, it is possible to vary the way in which these nanostructures self-organize during feather keratinization, and thus gain, lose or vary the hue and intensity of structural color. With this knowledge we can (bio)mimic nature's technology to produce colorful—and even iridescent—synthetic materials that do not lose intensity through exposure, unlike pigment colors. In this proposal, we intend to employ genomic, transcriptomic, and epigenomic approaches in several wild and domestic bird species to provide a general framework for understanding structural coloration in a wide range of species, thereby greatly expanding our understanding of this fascinating biological phenomenon.
