Anatomically diverse butterfly scales all produce structural colours by coherent scattering (original) (raw)
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Structural colour in animals—simple to complex optics
Optics & Laser Technology, 2006
Over the past 30 years, optics well known to the physicist have been identified in their multitudes in nature. Multilayer reflectors, diffraction gratings, liquid crystals and structures that scatter light-devices explained using ''simple'' optical theory-have been found in animals with a diversity of designs. For many years the potential to employ these designs commercially has been clear, although only one optical device in animals has been taken through to the manufacture stage-the fly-eye antireflector. Now, with the beginnings of ''complex'' optical study in biological specimens, and consequent identification of photonic band gaps, animal reflectors are being taken seriously as promising first stages in the design process of optical engineers. However, natural photonic crystals are often highly complex structures at the nano-scale that may lie beyond the limits of current engineering. This in turn justifies the study of cellular engineering-maybe we can also exploit the flawless processes of manufacture employed by animals.
Interface Focus
Iridescent colours are colours that change with viewing or illumination geometry. While they are widespread in many living organisms, most evolutionary studies on iridescence do not take into account their full complexity. Few studies try to precisely characterize what makes iridescent colours special: their angular dependency. Yet, it is likely that this angular dependency has biological functions and is therefore submitted to evolutionary pressures. For this reason, evolutionary biologists need a repeatable method to measure iridescent colours as well as variables to precisely quantify the angular dependency. In this study, we use a theoretical approach to propose five variables that allow one to fully describe iridescent colours at every angle combination. Based on the results, we propose a new measurement protocol and statistical method to reliably characterize iridescence while minimizing the required number of time-consuming measurements. We use hummingbird iridescent feathers...
The nanoanatomical basis of sexual dimorphism in iridescent butterfly colouration
Australian Journal of Zoology, 2012
Structurally generated colours are at least as commonplace and varied components of animal signals as pigment colours, yet we know far less about the former, both in terms of the patterns and phenotypic variation and of their underlying correlates and causes. Many butterflies exhibit bright and iridescent colour signals that arise from a characteristic 'ridge-lamellar' scale surface nanoarchitecture. Although there are multiple axes of functional variation in these traits, few have been investigated. Here we present evidence that sexual dimorphism in the expression of a sexually homologous ridge-lamellar trait (iridescent ultraviolet) is mediated by sex differences in the density of lamellar-bearing scale ridges. This traitridge densityhas also been causally related to iridescent signal variation in other coliadines (e.g. C. eurytheme), which suggests that it may offer a common basis to both intra-and intersexual differences in ultraviolet wing reflectance among these butterflies.
BACKGROUND: The interdisciplinary field of animal coloration is growing rapidly, spanning questions about the diverse ways that animals use pigments and structures to generate color,