Even below ants, royal status is mostly a hereditary matter. But for Indian jumping ants, it is worth losing a bit of your brain, especially since you will always be able to grow it later.
Unlike other ant species, Indian ants jump (Harpegnathos souteraar) do not die with their queens. Selected women would rather take part in month-long antenna boxing matches to decide who becomes the new matriarch. The conquering female then expands her ovaries and shrinks her brain to three-quarters of its original size.
So far, so bizarre, but scientists have discovered another surreal turn in the life of the forest dwellers, black-eyed, cramped notches – If a woman is deposed from her throne, she will return to a worker, her ovaries shrink, her brain regrowth and resume her previous duties.
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“We found that their brains returned completely to their previous size within a month after returning to a subordinate worker,” lead author Clint Penick, an associate professor at Kennesaw State University, told WordsSideKick. “It was quite astonishing, and this is the first time that reversible changes in the brain size of this scale have been reported in an insect.”
As with most other ant species, colonies of Indian spring ants are strictly hierarchical. A queen is responsible for laying eggs – queens of some species, such as the weather ant, can produce up to 300,000 eggs a day – and the workers protect the colony, raise the larvae and hunt for food.
Where they differ is what happens when the queen is dead. Most ant colonies slowly disappear after their leader dies, the workers die one by one and the royal offspring leave to become queens of their own colonies.
But in an Indian spring ant colony, the death of the queen is the reason why more than half of the women of the colony are going to do a month-long tournament of fierce duel with their antennae. The workers who are able to activate their ovaries while constantly producing and receiving antenna spores in the face are then selected as the next queens, the researchers said. Once the ritual is over, the triumphant new queens release a pheromone to warn their fellow ants of their royal status.
According to the researchers, about five to ten females in a colony of 100 ants will become new queens.
Only after they have acquired queen status do these newly formed ant queens undergo more drastic changes. Changes in gene expression and a cascade of hormones driven by a burst of dopamine cause their ovaries to be up to five times their original size and their brain to decrease by 25%. The lifespan of these new queens ranges from six months to five years.
“The biggest changes to the brain occur in the optic lobes and the central brain,” Penick said. “Ants that win the tournament essentially become egg-laying machines, and they will generally never leave their nest or see daylight again. They also no longer have to hunt, care for larvae or defend the nest. All their needs are taken care of, so that they do not need the same level of knowledge to perform complex tasks. “
To test whether this metamorphosis was reversible, the researchers used a sample of 30 colonies that labeled two new queens from each colony. One of the queens from each colony was kept as a control and allowed to do their normal royal duties, while the randomly selected others were sent to solitary confinement for a month – where they were fed and kept in complete isolation from their fellow ants. is. Soon enough, the isolated new queens stopped laying eggs and behaved like workers again.
On their return to their colonies, the returning workers were seized and detained for several hours by their fellow men, probably because of their partially developed ovaries. After their release, they returned to their duties as queens. Later dissection, performed six to eight weeks later, showed the ovaries of the returned ants had shrunk and their brains had returned to their full size.
The researchers suspect that this bizarre plasticity may have evolved because the species experienced a higher than normal queen mortality rate in their natural nests in the Indian jungle, but it is not certain.
According to Penick, their study is not the only study that shows that animals change their brain structure in extreme ways. Species of songbirds do the same and regrow the part of the brain involved in singing learning before the breeding season.
“The typical wisdom I heard when I was growing up was that once you lose brain cells, they never grow back,” he said. “Now that we know that it occurs in the Indian jumping ant, it is possible that it occurs in other species. At least this research shows that even the brain of an ant has the tools to regrow itself, and many of the genes and regulatory networks involved in this are likely to be similar to other animals, even vertebrates. ‘
The researchers published their findings on April 14 in the journal Proceedings of the Royal Society B.
Originally published on Live Science