Scientists have found ancient fossils of an insect that had similar survival strategies as lichen or lichenized fungus. Researchers from the Capital Normal University published their paper in the journal eLife.
Throughout history, animals have mimicked other organisms or used camouflage to survive. One inspiration for animal mimicry was lichen, a symbiotic relationship between algae and fungus forming a dual organism.
Since fungi lack chlorophyll and are incapable of conducting photosynthesis like plants, they absorb organic substances such as carbon for nutrition. Meanwhile, algae are capable of photosynthesis for survival. Their symbiotic relationship allows both organisms to always access nourishment.
Lichen Survival
Lichens are also known to colonize surfaces like topsoil, rock, and tree bark, covering about seven percent of the terrestrial surface around the world. They thrive in arctic-alpine environments such as wet and higher montane forests.
Similar to how lichens survive by concealing itself, researchers discovered that the lacewing Lichenipolystoechotes, a moth that existed during Jurassic times, mimicked a particular lichen called Daohugouthallus ciliiferus. The fossil was dated 165 million years earlier than modern lichen-insect associations.
Another notable lichen-insect association is the peppered moth. During the Industrial Revolution, the peppered moth mutated to turn black so it could hide from predators on tree trucks and lichen that turned dark due to soot.
After the industrial revolution, lichen species re-emerged and helped paler moths survive since there was less soot and pollution. However, the evidence is lacking that could explain how the peppered moth first evolved the survival strategy of mutating colors.
Perhaps the earliest case of an insect mimicking plants dates back to the Middle Permian. Researchers have found evidence of katydids, insects related to modern-day crickets and grasshoppers, mimicking leaves for survival.
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Insect Mimicry
Hai Fang, who is completing her Ph.D. at Capital Normal University, said, "As lichen models are almost absent in the fossil record of mimesis, it is still unclear as to when and how the mimicry association between lichen and insect first arose. The key to answer[ing] this question is to find early examples of a lichen-like insect and a co-occurring lichen fossil."
In Daohugou 1, an area in Inner Mongolia, Fang's team discovered lichen mimesis that was 165 million years old. Among the samples, two lacewing species co-existed with lichen during the Middle Jurassic.
When they confirmed the existence of lichen during the Jurassic area, the researchers documented how the lacewing mimicked the dual organism, observing measurements and structural similarities. Evidence showed that lacewings settled in habitats where lichen flourished and had nearly replicated their appearance to hide from predators.
"Our findings indicate that a micro-ecosystem consisting of lichens and insects existed 165 million years ago in Northeastern China," said Yongjie Wang, a professor at the university. "This adds to our current understanding of the interactions between insects and their surroundings in the Mesozoic Era, and implies that there are many more interesting insect relationships awaiting discovery."
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