Unprecedented Sexual Strategy found in Ants Species Messor ibericus

A fundamental biological study, first detailed in the journal Nature in late 2025 and continuing to draw scientific attention in February 2026, has illuminated a previously unknown reproductive mechanism within the harvester ant species, Messor ibericus. This species, endemic to the Iberian Peninsula and the wider Mediterranean region, relies on a hybrid reproductive system where queens must mate with males from the closely related Messor structor to produce the sterile hybrid workers necessary for colony maintenance.

Research spearheaded by biologist Jonathan Romiguier and his cohort at the University of Montpellier uncovered a more profound level of biological manipulation: the M. ibericus queen can clone these foreign males using her own eggs. Scientists have formally designated this process "xenoparity," meaning "foreign birth," marking it as the first documented instance of this reproductive strategy in the animal kingdom. This mechanism allows the M. ibericus queen to produce male offspring that are pure genetic copies of Messor structor - clones - without requiring direct copulation with them, instead leveraging stored sperm from the M. structor species as a genetic template within the queen's reproductive tract.

This xenoparity is critically important as it enables M. ibericus colonies to expand into territories geographically distant from established M. structor populations, a phenomenon observed in regions such as Sicily or Andalusia. The M. ibericus queens utilize the stored M. structor sperm to fertilize eggs, subsequently discarding their own maternal genome to produce the male clones. This finding challenges the classic biological tenet that a species exclusively produces progeny from its own genetic lineage, demonstrating that a single queen can generate functional individuals belonging to two genetically distinct species.

Worker ants within M. ibericus colonies are confirmed hybrids, possessing mitochondrial DNA from the M. ibericus mother but nuclear DNA from the M. structor father, even when the colonies exist without any nearby M. structor presence. Current research in 2026 is focused on the precise cellular mechanism that facilitates the elimination of the maternal genome in the egg fertilized by M. structor sperm to achieve this male clone. This complex evolutionary strategy, sometimes referred to as "sexual domestication" or obligate interspecific cloning, suggests that M. ibericus and M. structor function as a single, interdependent evolutionary unit composed of two species.

The evolutionary history indicates that M. ibericus lost the ability to produce its own worker ants millions of years ago, making this reliance on M. structor sperm an essential survival mechanism. This adaptation guarantees the sustained expansion and flexibility of the M. ibericus species across the Mediterranean basin, illustrating evolution's capacity for reticulate connections between lineages.