School of Biological, Earth and Environmental Sciences, University College Cork, Cork T23 TK30, Ireland.
Environmental Research Institute, University College Cork, Cork T23 XE10, Ireland.
Biol Lett. 2020 Apr;16(4):20200063. doi: 10.1098/rsbl.2020.0063. Epub 2020 Apr 15.
Extant weevils exhibit a remarkable colour palette that ranges from muted monochromatic tones to rainbow-like iridescence, with the most vibrant colours produced by three-dimensional photonic nanostructures housed within cuticular scales. Although the optical properties of these nanostructures are well understood, their evolutionary history is not fully resolved, in part due to a poor knowledge of their fossil record. Here, we report three-dimensional photonic nanostructures preserved in brightly coloured scales of two weevils, belonging to the genus or , from the Pleistocene (16-10 ka) of Switzerland. The scales display vibrant blue, green and yellow hues that resemble those of extant . Scanning electron microscopy and small-angle X-ray scattering analyses reveal that the subfossil scales possess a single-diamond photonic crystal nanostructure. In extant , the near-angle-independent blue and green hues function primarily in crypsis. The preservation of far-field, angle-independent structural colours in the Swiss subfossil weevils and their likely function in substrate matching confirm the importance of investigating fossil and subfossil photonic nanostructures to understand the evolutionary origins and diversification of colours and associated behaviours (e.g. crypsis) in insects.
现存的象鼻虫表现出了一种显著的颜色范围，从柔和的单色调到彩虹般的虹彩，最鲜艳的颜色是由三维光子纳米结构产生的，这些结构位于表皮鳞片内。尽管这些纳米结构的光学特性已经得到很好的理解，但它们的进化历史还没有完全解决，部分原因是对它们的化石记录了解甚少。在这里，我们报告了瑞士更新世（16-10 千年前）的两种象鼻虫属（ 或 ）的具有鲜艳色彩的鳞片中保存的三维光子纳米结构。这些鳞片呈现出鲜艳的蓝色、绿色和黄色调，类似于现存的 。扫描电子显微镜和小角 X 射线散射分析表明，这些化石鳞片具有单一金刚石光子晶体纳米结构。在现存的 中，近角独立的蓝色和绿色色调主要用于伪装。瑞士亚化石象鼻虫中保存的远场、角度独立的结构颜色及其在底物匹配中的可能功能，证实了研究化石和亚化石光子纳米结构对于理解昆虫颜色及其相关行为（如伪装）的进化起源和多样化的重要性。
