IBERIAN harvester ant queens can lay eggs that hatch into a different species, as per a discovery reported recently in Nature that challenges basic ideas about what defines a species.

Researchers found that queens of Messor ibericus mate with males of another species, Messor structor, then store and use that sperm to fertilize some eggs.

In those eggs the queens apparently eliminate their own nuclear genetic material, so the offspring develop as effectively cloned M. structor males. M. ibericus colonies therefore produce both M. ibericus males and M. structor males, while the worker caste consists of female hybrids of the two species.

The team collected 132 males from 26 M. ibericus colonies near Lyon, France. About half had the nearly hairless phenotype of M. structor; the rest were hairy like M. ibericus. DNA tests showed that all males shared M. ibericus mitochondrial DNA — inherited from the mother — indicating they were born of M. ibericus queens. The two species are not close relatives: they diverged over 5 million years ago, a gap comparable to the human–chimp split.

Because field observations alone could leave room for doubt, the researchers also reared colonies in the lab. Males are rare in captivity, so it took monitoring some 50 colonies for two years before lab‑born M. structor males finally appeared — key evidence confirming the phenomenon.

The authors coined the term “xenoparity” (literally “foreign birth”) to describe it.

Experts call the system both baffling and elegant. “It’s an absolutely fantastic, bizarre story,” said Jacobus Boomsma, an evolutionary biologist not involved in the study. The arrangement appears mutually beneficial: M. ibericus secures a steady supply of workers and can carry M. structor males into areas where pure M. structor colonies are absent, helping that species spread.

Yet the setup may be unstable long term. The cloned M. structor males do not seem to breed with their own species, so they likely accumulate harmful mutations over generations, increasing vulnerability.

For now, however, the partnership persists across southern Europe as a striking example of reproductive innovation and coevolution.

(SD-Agencies)