In a discovery that challenges basic biological rules, researchers have found that Iberian harvester ant queens (Messor ibericus) can produce male offspring of two different species: their own species and Messor structor.
This unusual reproductive strategy, which scientists are calling xenoparity, means that one queen produces males that genetically belong to a species entirely different from hers—something thought impossible under standard definitions of how species reproduce.
What Exactly Happens? How Reproduction Works in These Ants
Here’s a breakdown of what the scientists discovered:
- Messor ibericus queens mate with Messor structor males, sometimes storing sperm over long distances.
- They produce hybrid female workers whose nuclear DNA comes from both species: mother (M. ibericus) and father (M. structor).
- When it comes to producing males, the queens can do something extraordinary: some eggs become males of their own species (M. ibericus), while other eggs become males of M. structor, even though their mitochondrial DNA remains that of M. ibericus—meaning the egg came from the queen.
- The process appears to involve the queen somehow removing or “deleting” her own nuclear genetic material from the eggs and relying essentially on the stored M. structor genetic material from sperm to create M. structor males.
Why This Matters: Implications for Biology and Evolution
This finding has multiple major implications:
- Species Boundaries are More Fluid Than We Thought
The very idea that an individual of one species can give birth to a male of a different species suggests there are mechanisms in nature that blur the biological species concept. - New Reproductive Strategies
This adds xenoparity to the list of known reproductive anomalies. It’s not just hybridization—it’s cloning/exploiting foreign genetic material in a way that supports the colony. - Ecological Advantages
Producing hybrid workers ensures colonies can function (they need workers to forage, build nests, etc.). By also cloning foreign-species males, queens may be ensuring they don’t lose access to the worker-producing mechanism even in places where M. structor populations are far away. - Evolutionary Biology & Genetics Questions
How often does this happen? What is the cellular mechanism for deleting the queen’s nuclear DNA? What are the long-term evolutionary consequences, like inbreeding, or maintaining multiple genetic lineages? These findings open many avenues for future research.
What “Xenoparity” Means and How it Differs from Other Phenomena
- Xenoparity is the term coined by the researchers to describe this strange mode of reproduction. It literally means “foreign birth,” where an organism uses reproductive material (sperm) from another species and produces offspring of that other species.
- This is different from ordinary hybridization, where two different species mate and produce offspring that carry DNA from both parents. In xenoparity, the queen produces males that are genetically (nuclear-DNA wise) almost entirely from the other species.
What We Still Don’t Know
- Exactly how the queen’s genetic material is removed in those eggs that become foreign-species males—is it immediately after fertilization? Or before?
- Are the M. structor males produced in this way fully functional as males from M. structor in terms of fertility and capability to mate with true M. structor queens?
- How widespread is this trait within other ant species, or beyond ants? Is xenoparity a one-off, or more common than we thought?
Conclusion
The discovery that Messor ibericus queens can produce male offspring of M. structor, in effect giving “birth” to ants of another species, turns much of what we believed about how species reproduce on its head. This phenomenon, xenoparity, highlights the intricate and sometimes bizarre strategies that evolution can produce, especially in social insects. For scientists, this opens up many fascinating questions about genetics, ecology, and speciation. For everyone else, it’s just another reminder that nature has surprises beyond our wildest imaginations.
