Scientists have revealed that queen ants in southern Europe can produce male clones of a completely different species, in a remarkable discovery that is shaking up the field of biology.
The unprecedented discovery, detailed in a study published in Nature earlier this month, upends long-held assumptions involving reproduction and the boundaries between species, as well as how the very concept of species is defined.
The new research reveals that queen Iberian harvester ants (Messor ibericus) can generate males from the closely related Messor structor species, even without mating with them. The unique ability involves a reproductive system known as “xenoparity,” which challenges past views on the ways species maintain genetic isolation and has the potential for reshaping scientists’ knowledge of evolutionary strategies in certain insects.
A Remarkable Discovery
Ordinarily, Messor ibericus colonies function through a hybrid system: queens must mate with M. structor males to produce workers, while mating with their own species’ males produces only new queens.
However, a paradox became apparent following the identification of dozens of thriving M. ibericus colonies that researchers found living in regions without any nearby M. structor populations.
Exploring this mystery, a team led by evolutionary biologist Jonathan Romiguier of the University of Montpellier examined male ants from 26 colonies, revealing two distinct types—hairy M. ibericus males and bald M. structor males.
During their investigation, sequencing confirmed something that otherwise would have seemed impossible: that both sets of males shared mitochondrial DNA from the same M. ibericus queens, ruling out the possibility of hidden M. structor queens somewhere nearby that may have been contributing to the colonies. Further laboratory experiments showed that nearly 10% of eggs laid by isolated M. ibericus queens contained M. structor males.
The remarkable discovery was confirmed during one especially remarkable instance, where the team observed that a queen was found to produce males of both species over a period of 18 months. This demonstrated that the ant queens were indeed cloning males from another species without passing along their own nuclear DNA.
What is a Species, Exactly?
At the heart of the discovery is the question of how, exactly, we define what separates one species from another. In an email to The Debrief, Romiguier explained that while we often think of this as a well-defined concept in the biological sciences, xenoparity forces us to rethink the boundaries between different species.
“Not every scientist actually agrees about what a species is in the first place,” Romiguier told The Debrief. “This is a very complex debate that is mostly subjective.”
“On one hand, the fact that M. ibericus and M. structor are different species is clear according to all the most common current definitions of what a species is,” Romiguier explained, citing morphological concepts related to species, such as the fact that the males of the two species in question differ morphologically.
However, he adds that there are other approaches to the issue, which include a phylogenetic species concept, where two species belong to distinct evolutionary lineages, as well as a population genetic concept that observes the fact that genomes diverged after more than 5 million years, yet with no gene flow.
Another example Romiguier cited involves species with relation to biology, wherein M. ibericus and M. structorare are unable to reproduce hybrids that maintain fertility, like how a mule, the offspring of a horse and a donkey, is infertile.
“On the other hand, an ant colony is often viewed as a single unit of selection,” Romiguier told The Debrief, further explaining that the colony effectively acts as a single organism that propagates its genome. “Here, M. ibericus and M. structor clearly act as a single unit of selection, as both are sexually interdependent and are part of the same colony, with a dedicated role that is necessary for the survival of the whole group,” he says.
In this context, M. ibericus and M. structor can be viewed less like a pair of distinctive species, and more like a two-species “superorganism” that operates as a single unit of selection. From this perspective, Romiguier says, it could be argued that the two varieties of ants can be considered a single species.
The team coined the term “xenoparity” to describe this unprecedented system, which Romiguier says forces scientists to rethink “what we mean by the concept of organism, individuality or species.”
While it remains unclear when this trait first emerged, Romiguier and his colleagues believe it was probably sometime after M. ibericus and M. structor diverged, which took place around five million years ago.
Next Steps
Now, the team hopes to uncover additional information about the exact genetic mechanism behind the phenomenon, which includes how maternal DNA is stripped away during the cloning process.
“Usually, during fertilization, the genetic material of the ova mixes with the genetic material of the sperm to give birth to the embryo,” Romiguier told The Debrief. “Here, the genetic material of the ova is eliminated at some point, leading to an ova with just the genetic material of the father that will develop into a clonal male.”
Romiguier likens this to how the process of artificial cloning in the lab would work, by eliminating the genetic material of an ova before injecting the genetic material of another individual in order to clone it.
“In the case of our ants, we still don’t know exactly how and when the maternal genome is eliminated,” Romiguier said, although he and his colleagues have a few ideas.
“It might be that the males fertilize an egg that does not yet have a nucleus, or that the maternal genome is eliminated by the paternal genome just after fertilization,” Romiguier explained.
Going forward, the team says they plan to try to unveil more about this process, which he says will require cell biological methodologies that will allow the researchers to visualize what occurs both before and after the fertilization of ova they plan to study.
Fundamentally, the team’s discovery represents not only a first for biology but also a stark example of how discoveries in the sciences often more closely resemble science fiction.
“This phenomenon reminds us that nature often surpasses fiction in terms of complexity,” Romiguier said.
The team’s recent study, “One mother for two species via obligate cross-species cloning in ants,” appeared in Nature on September 3, 2025.
Micah Hanks is the Editor-in-Chief and Co-Founder of The Debrief. A longtime reporter on science, defense, and technology with a focus on space and astronomy, he can be reached at micah@thedebrief.org. Follow him on X @MicahHanks, and at micahhanks.com.