Insects Is this a kind of grasshopper

Mimesis in insects is older than expected

Perfectly camouflaged: Many insects imitate details of their environment in order to escape the eyes of voracious hunters. This strategy, known as mimesis, is apparently much older than expected. This is now revealed by a newly discovered grasshopper fossil from France: The 270 million year old remains of the insect suggest that the animal disguised itself as a leaf during its lifetime, as researchers report in the journal "Nature Communications".

Caterpillars that imitate branches, birds that adapt their eggs to the ground or snails that camouflage their house with soil: there are an extraordinarily large number of examples of sophisticated camouflage strategies in the animal kingdom. Especially insects that live on the upper side of the leaves of plants are characterized by their ingenuity - above all the grasshoppers. Specimens such as the Walking Leaves or the stick insects even owe their names to their masterly camouflage.

The meaning of this phenomenon, also known as mimesis, is simple: By imitating plants or the ground, the animals protect themselves from predators. Fossil finds show that early ancestors of today's locusts used this strategy around 150 million years ago to avoid the eyes of voracious hunters. But the concept of camouflage clothing is possibly much older. At least that suggests a new discovery.

Fossil brings two surprises

The find is about 270 million years old fossil of the fore wing of a grasshopper, which was discovered in the south-east of France. Even the remains of the insect are amazing in themselves. Because it is the oldest known fossil of locusts and belongs to a new species within the family of leaf locusts (Tettigonioidea), as scientists working with Romain Garrouste from the Sorbonne University in Paris report. Until now, experts had assumed that these insects did not develop until 200 to 145 million years ago.

What is even more interesting, however, is that when the researchers examined the shape and structure of the wing, they found noticeable features. Both the shape and the veining of the wing showed modifications as they are also characteristic of mimetic locusts of today. The analysis made it clear that the insect disguised itself as a leaf while it was alive.

New enemies as the driving force

Although the researchers cannot exactly reconstruct which plant the locust imitated, one thing is certain: the leaf-like wing fossil moves the starting point of the evolution of the mimetic strategy at least 100 million years further into the past - from the Mesozoic to the Middle Age Perms.

Even then, the insects must have been exposed to threats similar to those of their modern relatives. “In the Middle Permian, more and more small, insectivorous vertebrates gradually developed. This diversification probably exerted considerable selection pressure on potential prey - and it was apparently large enough to produce the first examples of plant-imitating camouflage clothing, ”the team concludes. (Nature Communications, 2016; doi: 10.1038 / ncomms13735)

(Nature, December 22nd, 2016 - DAL)

December 22, 2016