Imagine opening an ant nest and finding that one queen’s sons do not all belong to her species. That is the life cycle reported for the Iberian harvester ant, Messor ibericus. The colony depends on males of a second species to produce its workers, and maintains those males through cloning. This is a naturally occurring reproductive system, studied through field sampling and laboratory observation. [2] [6]
Y. Juvé and colleagues published the peer-reviewed study in Nature on 3 September 2025. Its title, “One mother for two species via obligate cross-species cloning in ants,” captures the central finding. [1]
Why the workers matter
An ant colony relies on a division of labour. Queens reproduce, while workers perform tasks such as foraging and caring for the brood. Whether a female develops as a queen or worker can depend on environmental conditions, genetic influences, or both. It is therefore useful to separate two questions: which parents produced an ant, and which role that ant develops to fill. [5]
Earlier research had already identified an unusual arrangement called social hybridogenesis in Messor. Queens mate within their genetic lineage to produce future queens, but use males of a different lineage to produce workers. A study published online in November 2016, appearing in Molecular Ecology in 2017, found independent origins of this system in the genus. [3]
That background makes the new discovery easier to understand. A colony can preserve distinct reproductive lineages while repeatedly producing hybrid workers. Hybridization does not automatically mean that every member of the next generation belongs to one permanently blended population. The biological outcome depends on which individuals reproduce. [3]
How the researchers connected the evidence
The team analysed genome-wide data from 390 ants across five European species. All 164 sampled M. ibericus workers were identified as first-generation hybrids. To investigate the males, the researchers combined appearance, nuclear ancestry, mitochondrial ancestry and observations of developing broods. [1]
The university’s account describes a wider effort involving more than 120 populations and observations of about 50 laboratory colonies. Males fell into visibly different forms: one conspicuously hairy, the other almost hairless. Their genetic identities matched different species. These were complementary kinds of evidence, rather than an identification based on appearance alone. [2]
In one colony followed for 18 months, a single queen produced adult males of both species. Egg testing and isolated-queen observations provided additional evidence that the queens laid the other species’ offspring. This combination helps distinguish reproduction within a colony from the simpler possibility that an unrelated male wandered into a sampled nest. [1]
A hybrid worker and a cloned male are different
The words matter here. A hybrid receives nuclear ancestry from two different parental lineages. A clone preserves a nuclear genetic lineage without that usual mixing. In this ant system, hybrid workers and cloned males are different outcomes within the same colony’s reproduction. [2] [6]
Ants belong to the Hymenoptera, alongside bees and wasps. Their usual reproductive framework is haplodiploidy: females have two chromosome sets, while males generally have one. An unfertilized egg can develop into a male. This framework allows reproductive possibilities that differ substantially from familiar mammalian inheritance. [4]
One such possibility is androgenesis, development in which the embryo’s nuclear genetic material comes from sperm. Research on unusual honeybee development has also shown how flexible parental contributions can be in this group. That background establishes biological plausibility; it does not identify the exact cellular events occurring in M. ibericus eggs. [4]
Why the queen still contributes something
“Paternal nuclear DNA” does not mean the queen contributes nothing to the offspring. Mitochondria are structures involved in cellular energy metabolism and contain their own DNA, separate from nuclear chromosomes. Mitochondrial inheritance therefore offers another way to investigate maternal ancestry. [7]
The cloned M. structor males had mitochondrial ancestry matching their M. ibericus nestmates. Their nuclear and mitochondrial histories pointed in different directions. This distinction is important whenever the word “genetically” appears in a headline: scientists need to specify which genetic compartment they mean. [1]
What “sexual domestication” means here
The researchers interpret the arrangement as an evolutionary transition from using another species’ sperm to maintaining its males through cloning. Their term xenoparity describes females producing another species as part of their life cycle. The university describes the relationship as sexual domestication: maintaining the reproductive partner within the colony reduces dependence on finding that partner’s wild populations nearby. [2]
This language describes an evolutionary relationship, not a queen consciously planning a breeding programme. Nor does a useful outcome establish exactly why the system originated. A mathematical study published in Evolution Letters in 2021 showed that interactions between hybridization and genetic biases toward queen development could, under its assumptions, drive dependence on hybrid workers. [5]
That modelling result is a proposed route, not a historical record of these ants. It illustrates why “hybrids must be better workers” is an incomplete explanation: reproductive dependence can evolve through genetic conflict as well as potential benefits. Testing a particular evolutionary history requires evidence beyond a plausible model. [5]
The questions that remain
The study establishes an unusual inheritance pattern without resolving every developmental step. A useful next investigation would follow the earliest egg divisions and determine how maternal nuclear DNA is excluded. Comparing eggs destined for different offspring types could help connect the observed genetic outcomes to a cellular mechanism. These are research questions, not results demonstrated here. [1]
The work also offers a lesson in study design. In a June 2026 interview, senior author Jonathan Romiguier identified obtaining all castes, especially males, as a major practical obstacle. Looking only at the abundant workers would have left an essential part of the reproductive system unexplained. [6]
For biotechnology, the immediate value is a natural system for studying genome transmission and early development. A useful future experiment would test candidate mechanisms directly rather than infer them solely from adult ancestry. This research does not provide a ready-made cloning method for other animals. Its enduring appeal is simpler: a familiar-looking colony can conceal a reproductive partnership that becomes visible only when behaviour, development and genomes are studied together.
Sources and references
- Juvé, Y. et al. One mother for two species via obligate cross-species cloning in ants. Nature 646, 372–377 (2025).
- University of Montpellier Sexual Domestication: These Ants Clone Another Species to Survive. University of Montpellier, original research press release, 4 September (2025).
- Romiguier, J., Fournier, A., Yek, S. H. & Keller, L. Convergent evolution of social hybridogenesis in Messor harvester ants. Molecular Ecology 26, 1108–1117; online 17 November 2016 (2017).
- Aamidor, S. E., Yagound, B., Ronai, I. & Oldroyd, B. P. Sex mosaics in the honeybee: how haplodiploidy makes possible the evolution of novel forms of reproduction in social Hymenoptera. Biology Letters 14, 20180670 (2018).
- Weyna, A., Romiguier, J. & Mullon, C. Hybridization enables the fixation of selfish queen genotypes in eusocial colonies. Evolution Letters 5, 582–594; first published 16 September (2021).
- Myrmecological News Blog / Jonathan Romiguier Cloning the competition: Jonathan Romiguier on the bizarre world of Messor harvester ants. Myrmecological News Blog, researcher interview, 2 June (2026).
- National Human Genome Research Institute Mitochondrial DNA. Talking Glossary of Genomic and Genetic Terms; accessed 29 October (2026).
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