TY - JOUR
T1 - Evolution of brilliant iridescent feather nanostructures
AU - Nordén, Klara Katarina
AU - Eliason, Chad M.
AU - Stoddard, Mary Caswell
N1 - Funding Information:
The authors would like to thank the American Museum of Natural History (NYC) for allowing them to use the bird skin collections for plumage spectral color measurements. In particular, the authors thank Paul R Sweet, collections manager for the ornithological collections, for his help. The authors thank Kaspar Delhey for generously sharing R code to reproduce his measure of color diversity (voxel occupancy). The authors also thank Heinz Durrer for generously allowing them to reprint his microscopy images of iridescent nanostructures in Figure 2. Funding in support of this work was provided by Princeton University (MCS), a Packard Fellowship for Science and Engineering (MCS), the Grainger Bioinformatics Center (CME), and the National Science Foundation (Award 2029538 to MCS and Award 2112468 to CME). The authors would also like to thank Raphael Steiner, Jarome Ali, Merlijn Staps, and two anonymous reviewers for helpful discussion and feedback on an earlier version of this manuscript.
Publisher Copyright:
© Nordén et al.
PY - 2021/12
Y1 - 2021/12
N2 - The brilliant iridescent plumage of birds creates some of the most stunning color displays known in the natural world. Iridescent plumage colors are produced by nanostructures in feathers and have evolved in diverse birds. The building blocks of these structures—melanosomes (melanin-filled organelles)—come in a variety of forms, yet how these different forms contribute to color production across birds remains unclear. Here, we leverage evolutionary analyses, optical simu-lations, and reflectance spectrophotometry to uncover general principles that govern the production of brilliant iridescence. We find that a key feature that unites all melanosome forms in brilliant iridescent structures is thin melanin layers. Birds have achieved this in multiple ways: by decreasing the size of the melanosome directly, by hollowing out the interior, or by flattening the melanosome into a platelet. The evolution of thin melanin layers unlocks color-producing possibilities, more than doubling the range of colors that can be produced with a thick melanin layer and simultaneously increasing brightness. We discuss the implications of these findings for the evolution of iridescent structures in birds and propose two evolutionary paths to brilliant iridescence.
AB - The brilliant iridescent plumage of birds creates some of the most stunning color displays known in the natural world. Iridescent plumage colors are produced by nanostructures in feathers and have evolved in diverse birds. The building blocks of these structures—melanosomes (melanin-filled organelles)—come in a variety of forms, yet how these different forms contribute to color production across birds remains unclear. Here, we leverage evolutionary analyses, optical simu-lations, and reflectance spectrophotometry to uncover general principles that govern the production of brilliant iridescence. We find that a key feature that unites all melanosome forms in brilliant iridescent structures is thin melanin layers. Birds have achieved this in multiple ways: by decreasing the size of the melanosome directly, by hollowing out the interior, or by flattening the melanosome into a platelet. The evolution of thin melanin layers unlocks color-producing possibilities, more than doubling the range of colors that can be produced with a thick melanin layer and simultaneously increasing brightness. We discuss the implications of these findings for the evolution of iridescent structures in birds and propose two evolutionary paths to brilliant iridescence.
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U2 - 10.7554/eLife.71179
DO - 10.7554/eLife.71179
M3 - Article
C2 - 34930526
AN - SCOPUS:85122043743
SN - 2050-084X
VL - 10
JO - eLife
JF - eLife
M1 - e71179
ER -