Pterin Pigments Amplify Iridescent Ultraviolet Signal in Males of the Orange Sulphur Butterfly, Colias Eurytheme

摘要: Animal colouration is typically the product of nanostructures that reflect or scatter light and pigments absorb it. The interplay between these colour-producing mechanisms may influence efficacy potential information content colour signals, but this notion has received little empirical attention. Wing scales in male orange sulphur butterfly (Colias eurytheme) possess ridges with lamellae produce a brilliant iridescent ultraviolet (UV) reflectance via thin-film interference. Curiously, same contain pterin strongly wavelengths below 550 nm. Given UV functions as sexual signal C. eurytheme, it paradoxical wing are highly absorbing. We present spectrophotometric analyses wings before after removal show pterins both depress amplitude iridescence suppress diffuse emanates from scales. This latter effect enhances directionality spectral purity iridescence, increases signal's chromaticity content. Our findings also suggest amplify contrast scale background male's move during flight.