How keratin cortex thickness affects iridescent feather colours

Royal Society Open Science, vol. 10, pp. 220786

Abstract

The bright, saturated iridescent colours of feathers are commonly produced by single and multi-layers of nanostructured melanin granules (melanosomes), air and keratin matrices, surrounded by an outer keratin cortex of varying thicknesses. The role of the keratin cortex in colour production remains unclear, despite its potential to act as a thin film or absorbing layer. We use electron microscopy, optical simulations and oxygen plasma-mediated experimental cortex removal to show that differences in keratin cortex thickness play a significant role in producing colours. The results indicate that keratin cortex thickness determines the position of the major reflectance peak (hue) from nanostructured melanosomes of common pheasant ( Phasianus colchicus ) feathers. Specifically, the common pheasant has appropriate keratin cortex thickness to produce blue and green structural colours. This finding identifies a general principle of structural colour production and sheds light on the processes that shaped the evolution of brilliant iridescent colours in the common pheasant.

Authors 9

1. Deok‐Jin Jeon

   Yonsei University

   Affiliation as printed

   School of Integrated Technology, Yonsei Institute of Convergence Technology, Yonsei University, Incheon 21983, Republic of Korea

2. Seungmuk Ji

   Yonsei University

   Affiliation as printed

   School of Integrated Technology, Yonsei Institute of Convergence Technology, Yonsei University, Incheon 21983, Republic of Korea

3. Eunok Lee

   National Institute of Ecology

   Affiliation as printed

   Department of Research Planning, National Institute of Ecology, Chungcheongnam-do 33657, Republic of Korea

4. Jihun Kang

   Yonsei University

   Affiliation as printed

   School of Integrated Technology, Yonsei Institute of Convergence Technology, Yonsei University, Incheon 21983, Republic of Korea

5. Jiyeong Kim

   National Institute of Ecology

   Affiliation as printed

   Ecological Technology Research Team, Division of Ecological Applications Research, National Institute of Ecology, Chungcheongnam-do 33657, Republic of Korea

6. Liliana D’Alba Aachen Naturalis Biodiversity Center

   Naturalis Biodiversity Center · Ghent University

   Affiliation as printed

   Evolution and Optics of Nanostructures Group, Department of Biology, Ghent University, Ledeganckstraat 35, Ghent 9000, Belgium

   Naturalis Biodiversity Center, Darwinweg 2, Leiden 2333 CR, The Netherlands

7. Marie Manceau

   Centre National de la Recherche Scientifique · Inserm · Collège de France · Université Paris Sciences et Lettres · Centre Interdisciplinaire de Recherche en Biologie

   Affiliation as printed

   Center for Interdisciplinary Research in Biology, CNRS UMR7241, INSERM U1050, Collège de France, Paris Sciences et Lettres University, 75006 Paris, France

8. Matthew D. Shawkey

   Ghent University

   Affiliation as printed

   Evolution and Optics of Nanostructures Group, Department of Biology, Ghent University, Ledeganckstraat 35, Ghent 9000, Belgium

9. Jong‐Souk Yeo corresponding

   Yonsei University

   Affiliation as printed

   School of Integrated Technology, Yonsei Institute of Convergence Technology, Yonsei University, Incheon 21983, Republic of Korea