Insect wings can develop from the feet of a crustacean

The first wings on Earth may have evolved from the feet of an ancient, flightless crustacean.

Today, modern crabs, lobsters, shrimp and crayfish are sometimes called sea bugs, and as part of the arthropod family – marked by strong body armor and split joints – the name makes no sense.

Scientists now believe that the first insects evolved from aquatic forms of crustaceans that emerged about 8080 million years ago. As terrestrial ecosystems become more complex, after about a million million years, wings will allow them to be carried in the air.

If true, it means that ancient insects roamed the planet long before birds, bats, and tirosores – so where did they get that ability?

It’s an easy question that has plagued experts for centuries. A century-old hypothesis suggests that the wings of insects are an evolutionary innovation that develops The Novo From random buds of tissue during development.

A more recent view is that they arose from existing creations already present in ancient crustaceans, gradually morphing into something more useful out of the water over time.

The gills of these ancient crustaceans are one of the top attachments because they have both joints and muscles. In some crustacean larvae, they also look like mini-wings.

But two new papers on distant relatives of winged insects suggest their feet are a better match.

Beating certain genes like shrimp Parhaye Havanesis, The first study shows an insect wing-like gene network operating both in the crustacean’s body armor and in the leg part near his body. This indicates that the two have somehow squeezed on the body wall and are back to form wings again.

Another study found something similar. By cracking out specific genes, the researchers compared how the six-legged parts on a fruit fly and other insects are connected to seven or eight leg segments. P. Hawinesis.

In the end, the first six parts of the crustacean’s legs, from the ‘toe’ to the body, were nicely matched to the first six parts found on the insect’s feet. But this begs the question – where did the seven and eight segments of the crustaceans go in insects?

The authors found his answer in a paper written in 1893. This suggests that these nearby ‘lobes’ at the feet of the crustacean have merged into the body wall of the insect. Since then, it has been noted that in the embryos of many insects, the leg part closest to the body actually fuses on the body wall during development.

“But I still don’t have a story wing,” explains Heather Bruce, a molecular biologist at the Woods Hall Oceanographic Institute.

“So I kept reading and reading, and I came up with this 1980s theory that insects incorporated part of their proximal legs into the body wall, but the small lobes on the legs went backwards and formed wings.”

Using genomic and fetal data, Bruce and his colleagues found evidence to support this.

First, they say, the adjacent leg lobes become integrated into the body wall. Then, once there, the nearest segment moves backwards, forming insect wings later.

“Complementary leg- and wing-gene perspectives lead these groups to agree on answers to some key questions about crustacean-winged insect mutations,” write two independent experts in a review of two studies. Nature Ecology and Evolution.

“They agree that the side wall of the organism is the homelogs of the bare leg segment. On the other hand. They also agree that the wing consists of elements of the body walls that are taken from the crustacean foot. “

However, the study does not agree on every point. The first study supports the hypothesis known as the “Dual Origin” hypothesis, which contributes to the development of the wing in both very close leg segments and body wall. Or, as the authors put it, “innovation through the merger of two separate tissues”.

The second paper proposes a more gradual and complex transformation that mainly concerns the leg parts. According to their findings, the two closest leg parts first merged into the body wall of the insect, and then only the closest leg part squeezed into the back of the feather.

Bruce Fig. 1. Press release 1024x561(Bruce and Patel, Nature Ecology and Evolution, 2020)

The difference is subtle, and more research is needed to show – if at all – more appropriate. But the similarities between the studies provide an inevitable solution to the question of whether the previous theories about the evolution of the insect’s wing are appropriate.

Bruce argued for many years that ancestral crustaceans once had eight-legged parts. In today’s times On the other hand, She argues, one of these is embedded in the body wall, while in the fruit flies, one is embedded in the body wall and the other in its wing.

This gives the insect’s wings a single appearance of a “dual root”, where the body wall and the wing of the foot form, while in fact, the authors say, the insect’s body wall itself is taken from the closest leg parts.

“While the wings are now an extension of the organism’s body wall, they are bound to the leg part of the arthropod of one of their original ancestors,” the authors conclude.

It’s a neat idea that helps bring together many competitive hypotheses, but in all likelihood, it won’t end the mystery. In just the last 10 years, we have come to learn a lot about insect evolution.

Prior to genomic research, we did not even realize that crustaceans and insects were very closely related in the arthropod family, which is why so many people thought that the wings of insects did not spread anywhere.

Giles, segmented legs and body armor of crust stations have now given us direct targets to study.

“People are very excited by the idea that something like the wings of an insect could be an evolutionary novelty,” says Patel.

“But one story that emerges from genomic comparisons is that something is not new; everything came from somewhere. And, in fact, where can you find it.”

Agree on where the other thing is.

“Nevertheless, the origin of the insect’s wings remains a mystery. Research from both groups has led to exciting ways to solve this mystery.” Nature Review.

Both the first and second papers were published Nature Ecology and Evolution.