Spanish harvester ants are domesticating another ant species, and cloning its males to keep their colonies running.
In almost every living thing, a mother gives birth to her own species. That's practically the definition of a species. But in 2025, a team of researchers found an ant queen that breaks that rule. She lays eggs that hatch into two different species.
Queens that can't make their own workers
These are Iberian harvester ants, Messor ibericus, seed-eating ants from southern Europe. And they have a strange problem: their queens can't produce workers on their own.
When an Iberian queen mates with a male of her own species, her daughters become new queens. To get workers, she needs sperm from a different species, the builder harvester ant, Messor structor. Every worker in an Iberian colony is a hybrid between the two species. Biologists call this sexual parasitism, or sperm parasitism. The queen uses another species just for its sperm.
That works as long as builder harvester ants live nearby. But Iberian harvester ants have spread to places where builder harvester ants don't live. So how do they keep making workers?
A mystery on Sicily
Researchers led by Jonathan Romiguier at the University of Montpellier kept finding something that didn't make sense. Inside Iberian harvester colonies, there were builder harvester males. On the island of Sicily, they found them more than a thousand kilometres from the nearest wild builder harvester colonies.
The team, led by Yannick Juvé, looked at males from 26 colonies and found two kinds: hairy Iberian males and bald builder males. Then they sequenced their DNA, raised colonies in the lab and followed 286 eggs from five of them.
A mother of two species
The answer was stunning. Iberian queens were laying the builder harvester males themselves.
When the queen makes one of these males, she lays an egg whose nucleus carries only builder harvester DNA, from sperm she stored when she mated. Her own genes are removed. The result is a male builder harvester ant, a clone of the father, born from an Iberian queen. The two species split apart about 5 million years ago, yet one mother gives birth to both.
The researchers named this "xenoparity," meaning "foreign birth." It's the first time any animal has been found naturally producing members of another species as a normal part of reproducing.
Domesticated males
These cloned males are then available to mate with the colony's young queens, so the next generation can produce hybrid workers too. The queens don't need to find builder harvester ants in the wild anymore. They carry their own supply, copied from generation to generation.
And the clones have changed. They're less hairy than wild builder harvester males. Because of differences like this, the researchers suggest the cloned males are a domesticated line of the builder harvester ant, kept and bred by another species. The entomologist Jessica Purcell, who wasn't involved in the study, suggested that these males have become an integral part of Iberian harvester populations.
It works a bit like how people keep dogs or cattle. A species that started out as a wild partner now lives and breeds inside someone else's household, changed by the people who keep it.
Rewriting the rules
We usually think of a species as a group that breeds with itself and stays separate from others. The Iberian harvester ant shows how blurry that line can be. Its colonies are made of two species, need both to survive, and are run by queens who give birth to both.
Harvester ants are some of the most popular ants among keepers. If you'd like to keep a harvester species, read Harvester ants as pets in Canada.
Further reading
- Juvé, Y., Lutrat, C., Ha, A. et al. (2025). One mother for two species via obligate cross-species cloning in ants. Nature.
- Purcell, J. (2025). News and Views commentary on Juvé et al. Nature.
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