title: Coloration mechanisms and phylogeny of Morpho butterflies.
abstract: Morpho butterflies are universally admired for their iridescent blue coloration, which is due to nanostructured wing scales. We performed a comparative study on the coloration of 16 Morpho species, investigating the morphological, spectral and spatial scattering properties of the differently organized wing scales. In numerous previous studies, the bright blue Morpho coloration has been fully attributed to the multi-layered ridges of the cover scales' upper laminae, but we found that the lower laminae of the cover and ground scales play an important additional role, by acting as optical thin film reflectors. We conclude that Morpho coloration is a subtle combination of overlapping pigmented and/or unpigmented scales, multilayer systems, optical thin films and sometimes undulated scale surfaces. Based on the scales' architecture and their organization, five main groups can be distinguished within the genus Morpho, largely agreeing with the accepted phylogeny.
authors.affiliation: Biophysics Group, Institute of Physics, University of Antioquia, Calle 70 #52-21, AA 1226, Medellín 050010, Colombia mantonio.giraldo@udea.edu.co.
authors.forename: M A
authors.identifier: 0000-0003-3437-6308
authors.initials: MA
authors.lastname: Giraldo
authors.affiliation: Tokyo University of Science, Faculty of Science and Technology, Department of Physics, 2641 Yamazaki, Noda-shi, Chiba-ken 278-8510, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Yoshioka
authors.affiliation: School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA.
authors.forename: C
authors.initials: C
authors.lastname: Liu
authors.affiliation: Computational Physics, Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, Groningen NL-9747 AG, The Netherlands.
authors.forename: D G
authors.initials: DG
authors.lastname: Stavenga
mesh_terms: D000818:Animals; D002080:Butterflies / Q000033:anatomy & histology / Q000502:physiology* / Q000648:ultrastructure; D055620:Optical Phenomena; D010802:Phylogeny; D010858:Pigmentation / Q000502:physiology*; D012542:Scattering, Radiation; D013045:Species Specificity; D013057:Spectrum Analysis; D014921:Wings, Animal / Q000033:anatomy & histology / Q000648:ultrastructure
keywords: Butterfly phylogeny; Multilayers; Scatterometry; Spectrophotometry; Thin films; Wing scales