Spanish ants are using other species as “sexual livestock” to expand across Europe. And it’s working for them

Nature has given us many ways to reproduce. From the simplest mechanism (clonality) to really very elaborate systems of sexual reproduction: where some species generate males and females, others produce a huge number of ‘morphs’ depending on the season, population density or social caste.

But in all these cases, even the most complex ones, “the phenotypes produced by a female invariably belong to the same species.” Or so we believed. Because the Spanish ants have done so by jumping that “apparently universal restriction” into the air and are taking advantage of it to domesticate other species at will.

They are doing what? As it sounds: after examining more than 120 populations and sequences of almost 400 different individuals, researchers from the University of Montpellier they came to the conclusion that the queens of Messor ibericus they are cloning males Messor structor to create hybrid workers that allow them to progressively expand throughout Europe.

Evidently, although these hybrid workers are used as the workforce of the anthill, we are not talking about a system of slavery of other species analogous to the human systems of ancient times. However, it is fun and very interesting.

Juvé et al. (2025)

Why is this happening? When we talk about cocial insects, colonies function almost as if they were factories: if there are no workers, there is no nest, no food, and no viable reproduction. What happens in this case is that (according to the researchers) the queens of the Messor ibericus They cannot produce viable workers without the genetic contribution of other species.

And, without thinking twice, they do it.

Why is it important? For many reasons, but above all because it opens up an incredible melon: it brings back to the debate table the real meaning of “being a species.” It also forces us to rethink what we know about sexual reproduction and allows us to understand colonies as ‘superorganisms’ that are much more complex than we believed until now.

So… can we really talk about sexual domestication? In this context, ‘sexual domestication’ appears as a visual metaphor of a complex process. However, there is no doubt that the appearance of colonies with internal reproductive ‘livestock’ changes the rules of the game. And not only on a scientific level: the fact that they are gaining ground throughout the continent shows that the strategy is successful. Very successful.

Towards a European hegemony of the Spanish ant… No no. We can hardly say that. Today, all the ants on the continent are experiencing a real invasion: that of the Argentine or red fire ants. This is a biological invasion linked to globalization.

In this case, what is happening is that by freeing yourself from dependence on M. builder (because it can produce reserves of its genetic material without needing colonies of this species), the M. ibericus They can move with complete freedom and that means they are moving into new and unexplored territories.

But the complete battle, facing the fire ant, is yet to come. And they are already losing it.

Image | Phil Honle

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