<h1 class="pgc-h-arrow-right" > Academician Wei Jiangchun's research group cooperated with Capital Normal University to discover the oldest insects with mimetic lichens 165 million years ago</h1>
Mimesis is one of the most successful survival strategies in animal evolution. As the most abundant species of organisms on earth, insects have evolved rich and diverse mimetic taxa, such as dead leaf butterflies that simulate dead leaves, orchid praying mantises that simulate orchids, and bamboo sygropods that simulate branches. However, the origin and evolution of insect mimesis are still unclear, and mimic research has become a hot spot and difficulty in biological research.
Recently, Wei Xinli, a researcher in Wei Jiangchun's research group, and Wang Yongjie's team from Capital Normal University jointly published a research paper entitled "Lichen mimesis inmid-Mesozoic lacewings" in eLife, a top journal of biology, which discovered the insects of the oldest mimetic lichen 165 million years ago and revealed the self-protection mechanism of the earliest insect mimetic lichen.
Lichen is a symbiote of fungi and algae or cyanobacteria, because of the leafy body with a similar plant shape, it was first considered to belong to plants, and subsequent studies found that its shape was mainly controlled by fungi as the main body, so it was classified into the fungal world. Lichens usually epistaxially occur on surfaces such as bark, rocks and soil, and are widely distributed from the polar to the tropics, occupying 7% of the Earth's land surface. Lichens can secrete substances such as lichen acid to corrode rocks and promote the formation of surface soil layers, so lichens are often called "pioneer organisms". In modern ecosystems, lichen acid secreted by lichen makes many animals reluctant to approach lichen, so a complex and special micro-ecological system is formed between lichen and 'lichen tolerant animals', and lichen and insects of mimetic lichen are one of the most representative relationships. The most famous example of the relationship between lichens and insects is the "industrial blackening phenomenon" of the birch ruler moth in the 19th century, with the industrial revolution caused a lot of pollution, accompanied by the demise of lichens on the bark, resulting in the camouflage of lichens of light-colored birch ruler moths more easily preyed by birds, the number of dark birch ruler moths increased, as the environment improved, after a large number of lichens recovered, the number of light-colored birch ruler moths increased, this classic case is also known as "Darwinian evolution in action".
For now, the origin and early evolution of insect mimetic lichens remains a research gap, and the key to solving this problem is to find lichens in older formations and similar insects. The earliest reported fossils of suspected lichen were found in the Early Devonian strata about 400 million years ago, but their taxonomic location has been questionable. Scholars who study living lichens have long believed that truly large lichens appeared no earlier than 65 million years ago. Around the scientific problem of whether there are more ancient large lichens and insects in mimetic lichens in the older Mesozoic Era, Wang Yongjie's team of Capital Normal University and Wei Xinli, a researcher in Wei Jiangchun's research group, have conducted collaborative research on this. Using fossil sectioning and scanning electron microscopy technology, a detailed study was conducted on the suspected lichen fossil Daohugouthallusciliiferus found in the Jurassic Yanliao insect group in Ningcheng County, Inner Mongolia, and key structures such as fungal hyphae and algal cells and their entanglements were found, indicating that D. Ciliiferus is a symbiote composed of fungal and algal cells that proves its lichen properties with conclusive evidence, and is the earliest fossil of large lichen found so far, advancing the appearance of large lichen by nearly 100 million years. It provides new evidence for studying the early evolution of lichens.
Figure 1 Slice scanning electron microstructures of Daohugouthallus ciliiferus. A. Lichencoplear cortex structure, B-H. Fungal hyphae winding or joining green algae cells
This study was conducted in lichen fossil D. A veined insect, Lichenipolystoechotes, was found in the same formation where ciliiferus appeared, Lichenipolystoechotes. Through comparative analysis, it was found that the wing spots were compared with D. The morphology of the phyllates of ciliiferus is very similar; through the width of the wing spots of insects and the D. Random measurements and statistical analysis of the leaf width of the ciliiferus fossil showed that the insect had a high degree of similarity with the lichen, and a large number of black spots were found on the insect's wing spots, and similar spots were also found on the D.ciliiferus leaf body, and this structural detail further increased the similarity between the two. Thyridosmylus paralangii is a class of insects with similar wing spots in the order Phytophalidae, which live in a relatively humid environment rich in moss and lichens, and have a very good consistency with the environment; when the Jurassic period lichen moss inhabited D. In the environment of ciliiferus, the similarity between the two makes the lichen moth form a high degree of consistency with the environment. Thus, the Jurassic lichen spider gained a survival advantage by simulating D.ciliiferus, the first and oldest example of insect simulated lichen ever discovered, filling the gap in the study of fossil insect mimetic lichens, proving that insects and lichens had formed a complex interaction 165 million years ago.
Fig. 2 Photographs and line drawings of fossil insects of lichen butterflies
Fig. 3 Photographs of lichen fossils and statistical results of insect wing spots and lichen leafforms
Figure 4 Ecological restoration of lichen butterflies
Fang Hui, a doctoral student at the School of Life Sciences of Capital Normal University, is the first author of the paper, a researcher of wei Xinli project in the Wei Jiangchun Research Group of the Institute of Microbiology of the Chinese Academy of Sciences, associate professor Wang Yongjie and Professor Liu Jiaxi of Capital Normal University as co-corresponding authors, and ConradC, a researcher at the National Museum of Natural History. Labandeira, master's students Ma Yiming and Zheng Bingyu and Professor Ren Dong are co-authors. The analysis of lichen fossils in the research process was guided by Academician Wei Jiangchun and researcher Chen Jianbin, and constructive suggestions were given. The research was funded by the Innovation Team Project of the Ministry of Education, the National Natural Science Foundation of China, the Beijing Natural Science Foundation of China and the Institute of Interdisciplinary Studies of the First Normal University.
Source: Institute of Microbiology, Chinese Academy of Sciences. Thesis Link:
https://elifesciences.org/articles/59007