Jewels of iridescence Mechanisms of structural color and its significance in insect systematics


SOCIETY FOR INTEGRATIVE AND COMPARATIVE BIOLOGY
2021 VIRTUAL ANNUAL MEETING (VAM)
January 3 – Febuary 28, 2021

Meeting Abstract


9-3  Sat Jan 2  Jewels of iridescence: Mechanisms of structural color and its significance in insect systematics Chow, A*; Lord, N; Louisiana State University AgCenter, Department of Entomology, Baton Rouge, LA ablechow29@gmail.com https://www.thelordlab.com/able-chow

Taxonomy defines the basic categories on which all biological research operates. In Jewel Beetles (Coleoptera: Buprestidae), the 8th most speciose Coleopteran family with >15,000 species, color is often utilized to distinguish between morphologically similar species. The taxonomically difficult genus Chrysochroa is assembled of several morphologically conserved species-complexes that exhibit a diversity coloration, and differential interpretations of perceived color have furthered taxonomic instability. Colors in the members of Chrysochroa are produced through organized, alternating layers of melanin and chitin in the epicuticle, forming Bragg stacks which selectively reflect specific wavelengths of light and change with the angle of light and the observer. In this research, we investigate color as an extended phenotype in the form of spectral reflectance measured through spectrophotometry, and as ultrastructural morphology analyzed through transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The resulting color data was combined with morphological and biogeographical analysis to produce a revision of the subgenus Chrooxantha (Buprestidae: Chrysochroa). Superficially similar taxa previously classified as the same species were revealed to possess distinctly different spectral reflectance patterns produced by divergent epicuticle ultrastructure. Dissection further revealed species level differences in internal morphology, and distributional boundaries indicative of allopatric speciation were discovered through biogeographical analysis. The ability to evaluate color objectively at multiple levels has opened up new suites of highly informative characters previously unavailable to taxonomists enabling further research in evolution and systematics.

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