Research has revealed that some ant queens possess the remarkable ability to produce offspring from two distinct species, a phenomenon not observed in any other animal. This groundbreaking discovery, made by a team of scientists, has drawn attention to the peculiar reproductive strategies of the Iberian harvester ant, known scientifically as Messor ibericus, found on the island of Sicily.
In a study published in the journal Nature, evolutionary biologist Jacobus Boomsma from the University of Copenhagen describes how these queens can generate cloned males of another species, Messor structor, which does not reside nearby. This unique reproductive capability allows the queens to blur the lines between species, creating hybrid workers without the necessity of mating with other species in the wild.
The research team notes that the reproductive strategy employed by these queens resembles a form of “sexual domestication.” The queens appear to have historically appropriated the sperm of Messor structor, thus establishing a system in which they can produce male clones whenever desired. This adaptation eliminates the need for nuptial flights, allowing the queens to maintain control over reproduction within their colonies.
Genetic analysis has shown that the offspring of these colonies comprise two separate species, both born from the same queen. The hybrids include hairy individuals of Messor ibericus and hairless Messor structor, with the closest wild populations of the latter residing over 1,000 kilometers away. The queen can mate with males from either species, generating new queens from Messor ibericus males and additional workers from Messor structor males.
Despite diverging over 5 million years ago, Messor structor has evolved to become a sort of “parasite” within the colony of Messor ibericus. However, the queen exerts full control over her genetic lineage. She can reproduce asexually, produce clones, or selectively fertilize her eggs with either her own species’ sperm or that of her male clones.
This unique reproductive mechanism results in offspring that either share the queen’s genetic material or derive solely from the male clones. The only genetic connection between the groups is the queen’s mitochondrial DNA, enhancing genetic diversity within the colony without reliance on external wild populations.
Researchers propose that these Iberian harvester ants constitute a “two-species superorganism,” challenging traditional notions of individuality in species. The male clones of Messor structor generated by the queens differ visually from those produced by Messor structor queens, yet their genomes are identical. Entomologist Jessica Purcell, who did not participate in the study, suggests that these males have become integral to the population of Messor ibericus.
Purcell emphasizes the significance of this genetic integration, likening it to a process known as horizontal gene transfer, which can yield a new combined genome and a distinct genetic lineage. The findings from this study not only expand the understanding of ant reproduction but also invite further research into the complexities of species boundaries and genetic interaction.
As scientists continue to explore the implications of these findings, the Iberian harvester ant stands as a testament to the extraordinary adaptability of life and the intricate web of relationships within ecosystems.
