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Journalism of Courage
It is assumed that when a living organism gives birth to a child, it will belong to the same species as the parent or parents. However, researchers have now found a species of ants that has turned this biological fact on its head. The queens of the Mediterranean harvester ant species, Messor ibericus, can produce male offspring of a different species, Messor structor, according to a new study.
The research was published in the journal Nature earlier this month. It was carried out by a team of international scientists based at different institutes in France, Italy, Bulgaria, and Austria.
Jonathan Romiguier, a biologist at the University of Montpellier in France and a co-author of the paper, told CNN, “We had a strong suspicion that something was very unusual about this species, but to be honest, we were far from imagining just how unusual it really was.”
In harvester ant colonies, female queens give birth to offspring, and male drones provide the sperm. The sterile female workers are responsible for nest building, child care, among other things. Romiguier and his colleagues were surprised when they found all the Messor ibericus workers were hybrid, with about half of their DNA matching Messor structor.
Such a hybridisation is not unknown among ant species. Several ant queens mate with males of other species to produce hybrid workers. But in the case of Messor ibericus, the scientists realised that their colonies were found in many areas in the Mediterranean where there are no Messor structor colonies. So, how are Messor ibericus queens finding Messor structor males to produce hybrid workers?
To find the answer, Romiguier and his colleagues collected DNA samples of Messor ibericus colonies. They found that there were numerous Messor structor drones living in these colonies. Further examination showed that these drones had mitochondrial DNA from Messor ibericus. As this type of DNA is only maternally inherited, it meant that the mother of Messor structor males was a Messor ibericus queen.
The scientists then isolated Messor ibericus queens and analysed the eggs laid by them. They found that about 10% of the eggs were entirely Messor structor. The scientists say this is like a “human having chimp babies”.
Scientists suggest that Messor ibericus queens are giving birth to two different species by cloning the Messor structor males’ genetic material from sperm stored in a specialised organ called a spermatheca. The resulting eggs do not consist of Messor ibericus DNA, except for the mitochondrial DNA, which is absent in sperm.
“By producing two species of males, the queen ensures that her daughters that become queens themselves can mate with males of both species. They use Messor ibericus sperm to make new queens, while Messor structor sperm is used to produce hybrid workers and new Messor structor males,” according to a report by New Scientist.
