Research has revealed that some ant queens possess the extraordinary ability to produce offspring from two different species, even when those species do not inhabit the same environment. This remarkable finding, which challenges conventional understanding of species reproduction, was highlighted by evolutionary biologist Jacobus Boomsma from the University of Copenhagen in a study published in the journal Nature.
Unprecedented Reproductive Strategy
The study focuses on the Iberian harvester ant, Messor ibericus, found on the island of Sicily. These queens demonstrate a unique reproductive strategy that enables them to blur the lines of specieshood. While it is known that some ant queens can mate with different species to produce hybrid workers, M. ibericus queens go a step further by giving birth to cloned males of a completely different species, Messor structor.
This cloning process allows M. ibericus queens to mate with these cloned males to generate hybrid workers within their colony. The researchers refer to this reproductive method as akin to “sexual domestication,” where the queens have managed to commandeer the reproductive mechanisms of another species, similar to how humans have domesticated dogs.
Through genetic analysis, scientists found that the offspring of these colonies consist of two distinct species: the hairy M. ibericus and the hairless M. structor. Notably, the nearest wild populations of M. structor are located over 1,000 kilometers away from Sicily. This remarkable adaptation allows these ants to reproduce without the need for nuptial flights, which are typically required to find mates from other species.
Control Over Genetic Diversity
The reproductive control exercised by the Iberian harvester queen is profound. She can reproduce asexually, creating clones of herself, or can fertilize her eggs using sperm from either M. ibericus or M. structor males. Additionally, she has the ability to “delete” her own nuclear DNA, using her eggs solely to carry the DNA of her cloned males. This results in a colony that contains genetic material from both species, yet all offspring share the queen’s mitochondrial DNA.
The interplay of these mechanisms leads to a form of diversity that does not rely on the presence of wild neighboring species for reproduction. The colony can be classified as a “two-species superorganism,” a concept that challenges traditional definitions of individuality within species. The M. structor males produced by M. ibericus queens exhibit genetic similarities to males produced by their own species’ queens, although their physical appearances may differ.
Entomologist Jessica Purcell, who was not involved in the study, noted that these findings suggest that the M. structor males have integrated into M. ibericus populations. She posited that this phenomenon could be likened to horizontal gene transfer, which involves the incorporation of one species’ genome into another, leading to a distinct genetic lineage.
This groundbreaking research not only sheds light on the reproductive complexities of ants but also raises significant questions about the evolution of species and their interactions. As scientists continue to unravel these intricate relationships, the implications for our understanding of biodiversity and species behavior could be profound.
