A Thing of Beauty

A unique feature of birds is their varied and colorful plumage, replete with striking patterns. By coupling a careful mapping of distinct feather features such as pigment color, distribution, and their temporal variationwith a cellular andmolecular analysis of melanocytes, Cheng-Ming Chuong and colleagues provide a roadmap for studying feather patterning in chickens. Notably, feather patterns arise through a combinatorial modulation of the presence, arrangement, and differentiation of melanocytes rather than through specific genetically encoded traits.One example of thepower of such simple integrative changes is the striped plumage of Barred Plymouth Rock chickens. In these birds, a previously identified defect in theCDKN2A/B tumor suppressor locus leads to a premature differentiation ofmelanocytes anda fluctuating loss ofmelanocyte progenitors,which, when coupledwith thegrowth of feathers, creates thealternatingblackandwhite chevron-shaped pattern. In another example, the authors explored the temporal control ofpigmentpatterning inTaiwanCountrychickens,whose feathersdisplay different colors from the distal tip to the proximal end. They find that temporal regulation of melanocyte progenitor activity during the creation of the distinct parts of a feather accounts for the color transitions. A thirdmodulator, conferring laced-edge feathers to Silver LacedWyandotte chickens turns out to be the pulp adjacent tomelanocytes, expressinga pigmentmodifier. Therefore, co-opting simple cellular functions affecting the topology of themelanocyteprogenitor niche is aneffectivemechanism for creatingcomplexpatterns that ultimately impact animalbehavior. Lin, S.J., et al. (2013). Science 340, 1442.