Concordance of the spectral properties of dorsal wing scales with the phylogeographic structure of European male Polyommatus icarus butterflies

Virág Krízsik,Zsolt Bálint,Krisztián Kertész,László Péter Biró,Gábor Sramkó,Gábor Piszter

doi:10.1038/s41598-021-95881-z

Abstract

The males of more than 80% of the Lycaenidae species belonging to the tribe Polyommatini exhibit structural coloration on their dorsal wing surfaces. These colors have a role in reinforcement in prezygotic reproductive isolation. The species-specific colors are produced by the cellular self-assembly of chitin/air nanocomposites. The spectral position of the reflectance maximum of such photonic nanoarchitectures depends on the nanoscale geometric dimensions of the elements building up the nanostructure. Previous work showed that the coloration of male Polyommatus icarus butterflies in the Western and Eastern Palearctic exhibits a characteristic spectral difference (20 nm). We investigated the coloration and the de novo developed DNA microsatellites of 80 P. icarus specimens from Europe from four sampling locations, spanning a distance of 1621 km. Remarkably good concordance was found between the spectral properties of the blue sexual signaling color (coincident within 5 nm) and the population genetic structure as revealed by 10 microsatellites for the P. icarus species.

Highlights

The males of more than 80% of the Lycaenidae species belonging to the tribe Polyommatini exhibit structural coloration on their dorsal wing surfaces
In a study on Polyommatus Latreille, 1804 subgenus Agrodiaetus Hübner, 1822 from 140 species belonging to the tribe Polyommatini (Polyommatinae), only 26 (18.5%) species were found with brown dorsal coloration of the males, all the other exhibiting structural coloration[16]
As we showed earlier in the investigation of the wing coloration of nine lycaenid species inhabiting the same habitat in the environs of Budapest, the coloration of the males, and the photonic nanoarchitectures which generates their color, are both different enough that a neural network type software can efficiently identify the species with a better accuracy than 90%14

Summary

Introduction

The males of more than 80% of the Lycaenidae species belonging to the tribe Polyommatini exhibit structural coloration on their dorsal wing surfaces. These colors have a role in reinforcement in prezygotic reproductive isolation. The wings of butterflies exhibit a richness of colors and patterns unrivalled in the living w orld[1,2,3,4] Many of these colors are efficiently used and optimized in sexual communication. (Rottemburg, 1775), one of the most common blue butterflies of Europe[21], it is of the order of only 10 nm[22] Both the reflectance spectra and the geometric parameters of the photonic nanoarchitectures allow species identification with an accuracy of 96% and 91%, r espectively[13,14]

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Conclusion