Scientists discover ant species capable of producing 'foreign' offspring

Ant queens do not usually blur species lines, yet the Iberian harvester ant (Messor genus) does exactly that. A new study reports queens that produce their own species and also generate males of a different species that help them raise hybrid worker daughters.

The authors call this reproductive mode xenoparity, which means giving birth to something foreign. It is not a trick or a glitch in the lab, it is part of the ants’ normal life cycle.

Messor ants have unique abilities

Jonathan Romiguier at the University of Montpellier led the work. His team sampled hundreds of ants across Europe and tracked who came from whom using genetic markers.

Workers in these colonies carried roughly equal parts of two genomes and showed far higher genetic diversity than queens, which flagged first generation hybrids.

The workers’ maternal side matched Messor ibericus ants and their paternal side matched Messor structor ants.

When researchers checked the males reared inside Messor ibericus ant nests, they saw two kinds, hairy and hairless.

Genetic tests showed the hairy ones were Messor ibericus ant males and the hairless ones were Messor structor ant males, and all shared the mother’s mitochondrial DNA.

The team also genotyped eggs and larvae from lab colonies. About one in ten early broods contained only Messor structor nuclear DNA, confirming that the queen had laid males of another species inside her own nest.

How cloning across species works

The key process is androgenesis, where an embryo develops using only the father’s nuclear DNA.

In these ants, the queen removes her own genetic contribution from certain eggs, allowing stored sperm from another species to provide the entire nuclear genome for a son.

That sperm is stored in a specialized organ called the spermatheca. Ant queens can keep viable sperm in this organ for years and release it in precise amounts when needed.

Ants also use haplodiploidy, where unfertilized eggs become males and fertilized eggs become females. The system makes it possible for male embryos to develop even when the egg lacks the mother’s nuclear DNA.

Queens mate with both species’ males, then use Messor ibericus ant sperm to produce future queens and Messor structor ant sperm to generate hybrid workers.

This division of labor keeps the colony supplied with caretakers and new reproductive females at the same time.

How Messor ants make this work

Workers only appear when the genomes of both species combine, so the colony depends on hybrids to function. If a queen used only her own species’ sperm, she would mainly produce future queens and not enough workers.

Producing males of another species solves a hard logistics problem. The queen does not need to find Messor structor males in the landscape if she can rear them inside her own colony and then mate with them later.

“To our knowledge, females needing to clone members of another species have not previously been observed,” wrote Romiguier. That statement underscores how unusual this life cycle is compared with typical animal reproduction.

Romiguier explained that females showing this unusual reproductive system are described as “xenoparous,” since they produce members of another species as part of their own life cycle.

The authors also describe a domestication-like path that likely started with interspecies mating and ended with queens rearing the other species’ males inside their nests.

What this means for species

Two species can keep distinct identities yet remain locked together by reproduction. Here, one species supplies queens and cytoplasm, and the other supplies the paternal genome for workers.

The study also documents a male lineage that is maintained clonally inside Messor ibericus colonies. Over time, such lineages can accumulate harmful mutations because recombination is limited.

The genetic signal that marks Messor structor as the father shows up in the hybrid workers across wide areas where wild Messor structor nests are absent.

On Sicily, for example, hybrid workers live more than 620 miles from the nearest known Messor structor population.

This system challenges simple textbook ideas about species boundaries. It shows that the social needs of colonies can sculpt unusual reproductive solutions that still persist in nature.

Why these Messor ants matter

Researchers want to know how the queen’s egg loses the mother’s nuclear DNA so reliably. The timing and cellular machinery that make androgenesis happen remain open questions.

They also want to map how far this reproductive strategy has spread and how stable it is in the long run. If genetic load builds up in the clonal males, there may be limits to how far these colonies can expand.

Biologists have described forms of sperm parasitism and social hybrid systems in other ants, but xenoparity goes a step further. Here, a female produces and then mates with males of another species as part of her own life cycle.

Cross species androgenesis is known in some clams and in plants, but those cases involve males exploiting the eggs of other species sporadically.

In these ants, female control flips the script, and the practice becomes a necessary step for colony success.

The work reframes how we think about cooperation and conflict between species. It also gives researchers a clear target for studying how genomes from different species can be combined in carefully controlled ways inside one social system.

The study is published in Nature.

—–

Like what you read? Subscribe to our newsletter for engaging articles, exclusive content, and the latest updates. 

Check us out on EarthSnap, a free app brought to you by Eric Ralls and Earth.com.

—–