TY - JOUR
T1 - Springtail coloration at a finer scale
T2 - mechanisms behind vibrant collembolan metallic colours
AU - Vanthournout, Bram
AU - Rousaki, Anastasia
AU - Parmentier, Thomas
AU - Janssens, Frans
AU - Mertens, Johan
AU - Vandenabeele, Peter
AU - D'Alba, Liliana
AU - Shawkey, Matthew
N1 - Publisher Copyright:
© 2021 The Author(s).
PY - 2021/7/7
Y1 - 2021/7/7
N2 - The mechanisms and evolution of metallic structural colours are of both fundamental and applied interest, yet most work in arthropods has focused on derived butterflies and beetles with distinct hues. In particular, basal hexapods - groups with many scaled, metallic representatives - are currently poorly studied and controversial, with some recent studies suggesting either that thin-film (lamina thickness) or diffraction grating (longitudinal ridges, cross-ribs) elements produce these colours in early Lepidoptera and one springtail (Collembola) species. Especially the collembolan basal scale design, consisting of a single lamina and longitudinal ridges with smooth valleys lacking cross-ribs, makes them an interesting group to explore the mechanisms of metallic coloration. Using microspectroscopy, Raman spectroscopy, electron microscopy and finite-difference time-domain optical modelling, we investigated scale colour in seven springtail species that show clear metallic coloration. Reflectance spectra are largely uniform and exhibit a broadband metallic/golden coloration with peaks in the violet/blue region. Our simulations confirm the role of the longitudinal ridges, working in conjunction with thin-film effects to produce a broadband metallic coloration. Broadband coloration occurs through spatial colour mixing, which probably results from nanoscale variation in scale thickness and ridge height and distance. These results provide crucial insights into the colour production mechanisms in a basal scale design and highlight the need for further investigation of scaled, basal arthropods.
AB - The mechanisms and evolution of metallic structural colours are of both fundamental and applied interest, yet most work in arthropods has focused on derived butterflies and beetles with distinct hues. In particular, basal hexapods - groups with many scaled, metallic representatives - are currently poorly studied and controversial, with some recent studies suggesting either that thin-film (lamina thickness) or diffraction grating (longitudinal ridges, cross-ribs) elements produce these colours in early Lepidoptera and one springtail (Collembola) species. Especially the collembolan basal scale design, consisting of a single lamina and longitudinal ridges with smooth valleys lacking cross-ribs, makes them an interesting group to explore the mechanisms of metallic coloration. Using microspectroscopy, Raman spectroscopy, electron microscopy and finite-difference time-domain optical modelling, we investigated scale colour in seven springtail species that show clear metallic coloration. Reflectance spectra are largely uniform and exhibit a broadband metallic/golden coloration with peaks in the violet/blue region. Our simulations confirm the role of the longitudinal ridges, working in conjunction with thin-film effects to produce a broadband metallic coloration. Broadband coloration occurs through spatial colour mixing, which probably results from nanoscale variation in scale thickness and ridge height and distance. These results provide crucial insights into the colour production mechanisms in a basal scale design and highlight the need for further investigation of scaled, basal arthropods.
KW - Collembola
KW - Diffraction grating
KW - Optical modelling
KW - Scale colour
KW - Scale structure
KW - Thin film
UR - http://www.scopus.com/inward/record.url?scp=85110945580&partnerID=8YFLogxK
U2 - 10.1098/rsif.2021.0188
DO - 10.1098/rsif.2021.0188
M3 - Article
SN - 1742-5689
VL - 18
JO - Journal of the Royal Society, Interface
JF - Journal of the Royal Society, Interface
IS - 180
M1 - 20210188
ER -