Messor ibericus and Messor structor males hatched from eggs laid by the same queen.
Creationists use a deliberately fuzzy and flexible definition of “kinds,” shifting its scope whenever it suits their argument. It can be narrowed down to the species level, broadened to a genus or family, or even stretched to encompass an entire order. On occasion, I’ve even seen it expanded to the absurdity of “animal kind,” depending on what the argument requires. This elasticity allows them to maintain the delusion that evolution never happens in the way biologists describe, and to caricature it instead as one species suddenly giving rise to a completely unrelated species in a single step — their parody of so-called “macro-evolution.”
But the case of the Iberian harvester ant (Messor ibericus) presents a real problem for this narrative. Here the definition of “kind” only needs to extend as far as members of a single genus. That still doesn’t rescue creationists, because this ant has evolved a remarkably complex reproductive strategy that undermines any notion of intelligent design and raises awkward questions about what a “kind” even is. Queens of M. ibericus can only reproduce successfully with males of a related species, Messor structor.
Such interspecies dependence is not unknown in either the animal or plant kingdoms, but M. ibericus takes it a step further. When a queen produces male offspring — instead of the usual sterile female workers — those males may be either M. ibericus or M. structor. In other words, she is doing precisely what creationists constantly demand as “evidence for evolution” - one species producing offspring of another species.
This recently discovered example of evolution’s capacity to produce novel and surprising outcomes that defy any description of intelligent design was the subject of a recent paper in *Nature*. It was also discussed in an article in *The Conversation* by two of the paper’s authors: Audrey O’Grady, Associate Professor in Biology, and Nataliia Kosiuk, a PhD candidate in Biological Sciences, both at the University of Limerick. Their article is reproduced here, reformatted for stylistic consistency.
One queen ant, two species: the discovery that reshapes what ‘family’ means in nature
The Iberian harvester ant is able to give birth to ants from two different species.
Imagine a mum who can have children from two different species. Family gatherings would be interesting, to say the least. In the insect world, this is no joke. A new study published in Nature shows that queens of the Iberian harvester ant (Messor ibericus) routinely lay eggs of not just their own kind, but also of males of another species, Messor structor.
The researchers even coined a word for it, xenoparity, meaning “foreign birth”. It pushes the boundaries of what we mean by “species”. And this is the first known case in the animal kingdom of this happening as part of an animal’s life cycle.
The most typical reproduction strategy in the natural world involves a mother and father of the same species who breed and produce sons and daughters, also of the same species.
However, there are exceptions to the rule. Social insects, ants in particular, are known to violate it. A 1999 study found that 17 out of 164 central Europe ant species are known to create hybrid offspring.
Typically, in ant colonies, fertilised eggs develop into workers and queens, and unfertilised eggs develop into males. All the ants that we usually see foraging are females who cannot reproduce (workers), but do all the other work. Ants that breed, female queens and males, normally have wings and can be seen during mating flights. Afterwards, males often die while the females found new colonies.
However, in some ant species, unfertilised eggs develop into female clones of the mother. This process is called parthenogenesis.
Generally, ant colonies which include different ant species may contain either one or several queens that can mate with either single or multiple males. Some ant species produce only wingless males that mate inside the nest and never participate in nuptial flights.
In 2002 an even more interesting reproduction strategy was found in two seed harvester ant species, common in southwestern US, whose queens lost their ability to produce female workers of their own kind. They need to mate with a male from a different species to lay eggs that develop into hybrid species female workers. This cross-species mating is essential for the survival of both species.
The new discovery
The article provides startling insights into ant reproduction. Workers (females) in these colonies are hybrids. Like the seed harvester ants, the Iberian harvester queens can’t make workers on their own. They need sperm from M. structor, and the daughters are half M. ibericus, half M. structor. This is similar to social hybridogenesis documented in other harvester ants, where only cross-species daughters become workers.
But the fascinating part is that Iberian harvester queens produce ordinary M. ibericus sons as well as M. structor sons. These males aren’t hybrids. They’re clones, carrying only their father’s DNA. Iberian harvester queens act almost like a rental womb. This resembles male-only cloning known from some clams and a stick insects.
Iberian harvester ants involve a rare example of male cloning.
M. ibericus and M. structor split from a common ancestor millions of years ago. They look and behave differently in the wild, with M. ibericus having smaller queens. Yet one is now literally producing the other. Multiple colonies of M. ibericus live together in habitats ranging from pastures to suburban areas. But M. structor ants are a mountain species and their colonies live separately. The two ant species can live close together in overlapping habitats in lanes and fields near mountains.
The cloned M. structor sons raised inside M. ibericus colonies don’t just differ genetically, they even look odd. Compared with their wild cousins, they appear almost hairless.
The most probable explanation of how this reproduction strategy evolved is a phenomenon called sperm parasitism. This is when females of one species use sperm of the males of another species to stimulate asexual reproduction or even partially incorporate the male’s genome into their offspring.
Over time, they cut out the middleman (adult M. structor males) and started making their own supply of cloned M. structor males. Instead, they mate with these clones that hatch in the colony nest.
It shows that evolution can re-engineer reproduction in radical ways. People sometimes like to think nature follows straight paths. Parents make their own species. Colonies stick to one lineage.
But evolution doesn’t care about our rules. So the next time you see ants marching across a path, remember, somewhere in southern Europe, there’s a queen casually running a two-species household. And you thought your family tree was complicated.
Audrey O'Grady, Associate Professor in Biology, University of Limerick and Nataliia Kosiuk, PhD Candidate in Biological Sciences, University of Limerick
This article is republished from The Conversation under a Creative Commons license. Read the original article.
AbstractWhat this strange reproductive system shows us is that nature does not operate within the tidy boundaries demanded by creationist rhetoric. A single queen can straddle two species, producing her own kind, hybrids, and even males of another species entirely. Such outcomes make nonsense of the idea that living things must forever reproduce only “after their kind.”
Living organisms are assumed to produce same-species offspring1,2. Here, we report a shift from this norm in Messor ibericus, an ant that lays individuals from two distinct species. In this life cycle, females must clone males of another species because they require their sperm to produce the worker caste. As a result, males from the same mother exhibit distinct genomes and morphologies, as they belong to species that diverged over 5 million years ago. The evolutionary history of this system appears as sexual parasitism3 that evolved into a natural case of cross-species cloning4,5, resulting in the maintenance of a male-only lineage cloned through distinct species’ ova. We term females exhibiting this reproductive mode as xenoparous, meaning they give birth to other species as part of their life cycle.
Main
Although clonality is the most straightforward mode of reproduction, most animal species take a more complex route6. In sexual species, for instance, reproduction requires the interaction of males and females, which typically means that two different morphs have to be produced7. Such complexity is further amplified in some species, in which females produce distinct morphs depending on seasonal conditions, population density or social caste8,9,10,11. Even in these extreme cases, a seemingly universal constraint persists: regardless of their morphological variation, phenotypes produced by a female invariably belong to the same species. Here, we report that this rule has been transgressed by Messor ibericus ants, with females producing individuals from two different species.
Previous studies on Messor genus ants have reported conflicting results, suggesting widespread hybridizations between species that rarely co-occur in Europe12,13. Here, a combination of field work, population genomic analyses and laboratory experiments provide the resolution of this paradox: females of one of the species (M. ibericus) clone males of the other (Messor structor), as they need their sperm to produce the worker caste. We discuss the evolutionary history of this natural case of cross-species cloning, which suggests a domestication-like process for exploiting another species’ gametes.
Queens depend on another species’ sperm
Population genetic analyses revealed that M. ibericus queens are unable to produce workers without mating with males of another species. To reach this conclusion, we analysed genome-wide data in 390 individuals (Supplementary Table 1) from five European species of the Messor genus (phylogenetic tree in Fig. 1a and Extended Data Figs. 1 and 2). In ants, workers and queens of the same species are diploid individuals expected to be genetically similar14. Our data showed that this is not the case in one out of the five species analysed. In M. ibericus, all worker genomes (n = 164) featured a 15 times higher heterozygosity than their queens or queens and workers of the four other species (n = 127; average of 0.797 versus 0.047 on 43,084 polymorphic sites, two-sided Wilcoxon rank-sum test P < 2.2 × 10−16; Fig. 1a). Such high heterozygosity levels suggest that M. ibericus workers are hybrids. We confirmed this hypothesis by conducting an analysis specifically designed to detect first-generation hybrids15, which identified all M. ibericus workers as such (Methods and Supplementary Table 1). With the exception of one Messor ponticus worker, queens and individuals of the other four species were identified as non-hybrids (Supplementary Table 1).Fig. 1: Obligate hybridization for worker production expands beyond parental species’ range.
a, Proportion of heterozygous positions on the total number of polymorphic sites (SNPs, n = 43,084) for queens and workers of M. ibericus (n = 220), M. ponticus (n = 12), Messor mcarthuri (n = 6), Messor muticus (n = 8) and M. structor (n = 45). Species individuals are arranged vertically according to their phylogenetic relationships (tree was built from one representative individual of each species; Extended Data Fig. 1). Each hybrid worker from M. ibericus colonies (n = 164) displays a pie chart representing its respective population ancestry proportion estimated from the fastStructure software16, with blue and red representing, respectively, M. ibericus (maternal) and M. structor (paternal) genome proportions. Average hybrid worker heterozygosity (n = 164) is significantly higher than average heterozygosity of M. structor queens or queens and workers of the four other species (n = 127; average of 0.797 versus 0.047, two-sided Wilcoxon rank-sum test, P < 2.2 × 10−16). b, Map representing the distribution of sequenced hybrid workers (n = 164). The distribution areas of each parental species have been estimated from our sampling and reports from the literature13,23. Hybrid workers localized in areas where both parental species co-occur are highlighted by a picture representing an M. ibericus queen (blue) with an M. structor male (red). Hybrid workers localized in areas without the paternal species are highlighted with the same picture but with a question mark instead of the father. SNP, single nucleotide polymorphism.
To identify the maternal origin of hybrid workers, we conducted a phylogenetic analysis on the maternally inherited mitochondrial genome. The resulting tree suggests an M. ibericus maternal ancestry, as all hybrid workers share the mitochondrial genome of M. ibericus sexual individuals (Extended Data Fig. 2). To identify the paternal species, we conducted a phylogenetic analysis of nuclear DNA after separating the maternal and paternal alleles of the hybrid genomes (Methods). The resulting phylogenetic tree showed that hybrid workers have an M. structor paternal ancestry, as all paternal alleles (n = 164) formed a well-supported clade with individuals of this species (Extended Data Fig. 3). Finally, a population structure analysis16 on 5,856 genes (44,191 variants) revealed that workers in M. ibericus colonies had virtually equal population ancestry proportions from M. ibericus and M. structor (averaging 0.49 and 0.51, respectively; Fig. 1 and Supplementary Table 1), which confirms further that they are first-generation hybrids.
These results imply that M. ibericus depends on hybridization for worker production, as already observed in cases of sperm parasitism17, in which queens exploit sperm from another lineage or species to produce workers12,18,19,20,21. Here, M. ibericus queens strictly depend on males of M. structor, which is a well-differentiated, non-sister species (Fig. 1a). This finding is particularly surprising because these two species do not share the exact same distribution area22,23. This paradox is clearly illustrated by hybrid workers being found across Southern Europe in spite of the total absence of their paternal species (Fig. 1b; 69 Mediterranean populations with confirmed M. ibericus but no M. structor colonies found). As even more compelling evidence, first-generation hybrid workers from the Italian island of Sicily are found more than a thousand kilometres away from the closest known occurrence of their paternal species. This raises the question of how queens can hybridize in such an isolated area (Fig. 1b). To solve this conundrum, we examined males from M. ibericus colonies more closely.
Queens produce males from two species
Morphological and molecular analyses showed that M. ibericus queens lay the M. structor males they require for worker production. By sampling 132 males from 26 M. ibericus colonies, we observed a sharp morphological dimorphism: 44% of sampled males displayed a dense pilosity (Fig. 2a), whereas the other 56% were nearly hairless (Fig. 2b). By conducting phylogenetic analyses including 62 hairy versus 24 hairless male nuclear genomes, we showed that the two morphs perfectly correspond to two different species (Extended Data Fig. 2). Whereas all hairy males group with M. ibericus, all hairless ones group with M. structor, which are two non-sister species that we estimated to have split more than 5 million years ago (Ma) (Methods, Fig. 2c and Extended Data Figs. 1 and 4). Multiple lines of evidence point to the production of males of both species by M. ibericus queens.First, M. structor males share the same mitochondria as their M. ibericus nestmates, pointing to common M. ibericus mothers for the whole colony (n = 24; Fig. 2, Extended Data Fig. 2 and Supplementary Table 1). This nuclear–mitochondrial genome mismatch is unique to males found in M. ibericus colonies, as it has not been observed in any other M. structor individual when found in their own species colonies (n = 53; Extended Data Fig. 2 and Supplementary Table 1). Second, genotyping 286 eggs or larvae from 5 M. ibericus laboratory colonies showed that 11.5% exclusively contained M. structor nuclear genome (Supplementary Note 1, Supplementary Table 2 and Supplementary Figs. 1 and 2). To confirm that such M. structor eggs were laid by M. ibericus queens and not workers, we isolated 16 queens and genotyped their newly produced eggs after 24 h. Again, we found that 9% of these eggs exclusively contained M. structor DNA (Supplementary Note 1, Supplementary Fig. 3 and Supplementary Table 3), which was not the case for broods produced by workers (see Supplementary Note 2 for details). Third, beyond genetic evidence, direct observations confirmed the emergence of adult males of both species from a single queen colony. We monitored a laboratory colony headed by a single M. ibericus queen for 18 months, checking broods weekly. Among seven eggs that developed into reproductive adults, two were identified as M. structor (hairless) males, and three as M. ibericus (hairy) males. Genomic analyses confirmed their morphological identification, with their whole nuclear genome matching solely either M. ibericus or M. structor (individuals ORT3M1 to ORT5M5; Extended Data Fig. 1 and Supplementary Table 1). Despite those M. structor births, we confirmed that the whole genome of the mother queen solely matches M. ibericus (ORT3Q1; Extended Data Fig. 1 and Supplementary Table 1). Other adult male emergences of both species (one of each) have been observed in another laboratory colony after 19 months of brood monitoring (Extended Data Fig. 5 for a picture of live individuals). Whereas male Hymenoptera typically inherit their nuclear genome from their mother through unfertilized eggs24, our results demonstrate that M. ibericus queens can produce males without transmitting their nuclear genome. This observation points to androgenesis (that is, male clonality), whereby a male provides the sole source of nuclear genetic material for the embryo25. Embryos devoid of maternal DNA have been observed in other groups, with the fertilization of non-nucleate ovules26 or the elimination of the maternal genome after fertilization27. In ants, both should spontaneously lead to males genetically identical to the sperm, as males are typically produced from haploid embryos through haplodiploidy24. At the intraspecific level, several cases of ants cloning males from their own species’ sperm have been observed28,29,30,31. Here, our results imply that this phenomenon has crossed species barriers, with male cloning from allospecific sperm stored in the spermatheca. Consistent with this explanation, M. ibericus queens are polyandrous and mate with both species’ males, as we retrieved sperm of both M. ibericus and M. structor when sequencing the spermatheca content of a queen that gave birth to both species (ORT3QS1 in Supplementary Table 1 and Extended Data Fig. 3; see also the BAN1QS spermatheca, which again contains spermatozoa of both species).Fig. 2: M. ibericus queens lay males from two different species.
M. ibericus queens lay males belonging to different species that differ morphologically (symbolized by male symbols in blue and red for M. ibericus an M. structor, respectively) and genetically. M. ibericus and M. structor males produce sperm for producing either new queens or workers, respectively. All share the same mitochondria (corresponding to the M. ibericus mitochondria, depicted here in blue; Extended Data Fig. 2). a, M. ibericus male photo (hairy). b, M. structor male photo (hairless). c, Phylogenetic tree of 223 non-hybrid individuals. Based on 5,656 nuclear genes (2,780,573 bp) and simplified from Extended Data Fig. 1. All represented nodes have maximal bootstrap support (100). Triangle widths are relative to the number of individuals. Branch lengths are relative to divergence time estimated from Fig. 1 and Extended Data Fig. 4 (see Methods for details). Scale bars, 1 mm. Credit: The top picture of an ant is adapted with permission from a photo from Flickr (https://www.flickr.com) taken by M. Kukla. bp, base pairs.
Maintenance of a clonal lineage of males
The combination of obligate hybridization for worker production (Fig. 1) and cross-species cloning (Fig. 2) points to the following scenario: M. ibericus queens first stored sperm from another species, then began to clone males from this sperm. This pathway is consistent with the widespread observation of facultative or obligate sperm parasitism17, a well-described phenomenon in which queens use sperm from a co-occurring lineage or species to produce their workers15,18,19,20,21,28,29,30,32. This strategy may have been selected either to benefit from potential worker hybrid vigour17 or to prevent queen-only production due to the fixation of a caste-biasing genotype18,32. In the ancestral state of this scenario, M. ibericus exploits sperm from co-occurring M. structor colonies (Fig. 3a), as has been observed in other Messor species12,33. In the derived state, M. ibericus queens directly produce the species they depend on, resulting in a clonal lineage of M. structor males they maintain in their colonies (Fig. 3b).
Fig. 3: Evolution of obligate cross-species cloning from sperm parasitism is reflected by different genetic and morphological lineages within M. structor.
a, Ancestral state of the M. ibericus reproductive system; n = 20 colonies deduced to correspond to this state have been sampled (Supplementary Table 1). b, Derived state of the M. ibericus reproductive system; n = 130 colonies deduced to correspond to this state have been sampled (Supplementary Table 1). Note that M. structor males have an M. ibericus mitochondrial genome, which is indicated with a red chromosome and a blue mitochondrion. c, Phylogenetic tree simplified from Extended Data Fig. 1 (as in Fig. 2c). Links to a and b are based on Extended Data Fig. 3, in which hybrid workers have been separated into paternal and maternal genomes. M. structor ‘clonal’ lineage stands for a clade composed of males from M. ibericus nests and the paternal genome of their worker daughters (derived state). M. structor ‘wild-type’ lineage stands for a clade composed of all castes from normal M. structor nests and the paternal genome of some hybrid workers found in M. ibericus co-occurring nests (ancestral state). d, Photo of M. structor males from M. structor colonies (hairy). e, Photo of M. structor males from M. ibericus colonies (hairless). Scale bars, 1 mm.Juvé, Y., Lutrat, C., Ha, A. et al.
One mother for two species via obligate cross-species cloning in ants.
Nature (2025). https://doi.org/10.1038/s41586-025-09425-w
Copyright: © 2025 The authors.
Published by Springer Nature Ltd. Open access.
Reprinted under a Creative Commons Attribution 4.0 International license (CC BY 4.0)
But the real puzzle, if we were to imagine this as the product of “intelligent design,” is why any designer would saddle a species with such a precarious arrangement. *Messor ibericus* queens are trapped in an evolutionary cul-de-sac, dependent on the genetic material of another species to keep their colonies functioning. That isn’t the hallmark of foresight; it’s the hallmark of evolutionary tinkering.
So, rather than evidence of design, the Iberian harvester ant offers us yet another glimpse into the creativity of evolution: a process that cobbles together workable, if sometimes bizarre, solutions from whatever material is available.
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