Animal coloration is an excellent system to study these questions. Its direct role in communication emerges from the balance between camouflage, signal efficacy and its information content. Structural colors, produced by the nanostructural arrangement of the tissue’s biomaterials, are particularly interesting for several reasons: first, they show a direct link between form and function, since minute nanostructural modifications can cause drastic differences in the produced color, with clear biological consequences. Second, in the case of feathers, an incredible diversity of colors can be produced from simply rearranging the same material components (keratin and melanin) found in most feathers. Finally, they can produce unique and stunning visual effects, such as iridescence.
My research focuses on the development and evolution of iridescent colors in feathers. At one level, I am interested in understanding the physical mechanisms of iridescent color production, and on how the nanostructural arrangement responsible for color production takes place during feather ontogeny. I am combining molecular and imaging techniques to both develop and test hypotheses on how this nanometer-level patterning originates during development. I am also interested in how evolution can explore these mechanisms in order to produce a broad diversity of colors. Iridescent colors have a great evolutionary potential because, once the potential for color-producing nanostructural organization is in place, a broad range of colors can be produced based on the same template. Therefore iridescent colors have the potential for extremely fast diversification. In addition, birds have evolved modified melanosomes in their feathers that increase the complexity of the system, and allow for additional morphological parameters that, when modified, can produce an even broader range of new, bright colors. Recent developments in phylogenetic comparative methods now allow the tackling of many interesting questions on morphological evolution and diversification.
Lamprotornis chalybaeus photo by Steve Evans from Citizen of the World [CC BY 2.0], via Wikimedia Commons