title: Spectrally tuned structural and pigmentary coloration of birdwing butterfly wing scales.
abstract: The colourful wing patterns of butterflies play an important role for enhancing fitness; for instance, by providing camouflage, for interspecific mate recognition, or for aposematic display. Closely related butterfly species can have dramatically different wing patterns. The phenomenon is assumed to be caused by ecological processes with changing conditions, e.g. in the environment, and also by sexual selection. Here, we investigate the birdwing butterflies, Ornithoptera, the largest butterflies of the world, together forming a small genus in the butterfly family Papilionidae. The wings of these butterflies are marked by strongly coloured patches. The colours are caused by specially structured wing scales, which act as a chirped multilayer reflector, but the scales also contain papiliochrome pigments, which act as a spectral filter. The combined structural and pigmentary effects tune the coloration of the wing scales. The tuned colours are presumably important for mate recognition and signalling. By applying electron microscopy, (micro-)spectrophotometry and scatterometry we found that the various mechanisms of scale coloration of the different birdwing species strongly correlate with the taxonomical distribution of Ornithoptera species.
authors.affiliation: Adolphe Merkle Institute, University of Fribourg, Fribourg, Switzerland Computational Physics, Zernike Institute for Advanced Materials, University of Groningen, Groningen, The Netherlands bodo.wilts@unifr.ch.
authors.forename: Bodo D
authors.identifier: http://orcid.org/0000-0002-2727-7128
authors.initials: BD
authors.lastname: Wilts
authors.affiliation: Laboratory of Neuroethology, SOKENDAI (The Graduate University for Advanced Studies), Hayama, Japan.
authors.forename: Atsuko
authors.identifier: http://orcid.org/0000-0002-8713-4313
authors.initials: A
authors.lastname: Matsushita
authors.affiliation: Laboratory of Neuroethology, SOKENDAI (The Graduate University for Advanced Studies), Hayama, Japan.
authors.forename: Kentaro
authors.identifier: http://orcid.org/0000-0002-4365-0762
authors.initials: K
authors.lastname: Arikawa
authors.affiliation: Computational Physics, Zernike Institute for Advanced Materials, University of Groningen, Groningen, The Netherlands.
authors.forename: Doekele G
authors.initials: DG
authors.lastname: Stavenga
mesh_terms: D000818:Animals; D002080:Butterflies / Q000502:physiology*; D004777:Environment; D005260:Female; D008297:Male; D008855:Microscopy, Electron, Scanning; D046529:Microscopy, Electron, Transmission; D010858:Pigmentation; D010860:Pigments, Biological; D012726:Sexual Behavior, Animal; D013053:Spectrophotometry; D014785:Vision, Ocular; D014921:Wings, Animal / Q000502:physiology*
chemical_list: D010860:Pigments, Biological
keywords: biogeography; biophotonic structures; filtering; iridescence; pigmentation; reflectance