Neat!

The workers in Iberian harvester ant (Messor ibericus) colonies are all hybrids, with queens needing to mate with males from a distantly related species, Messor structor, to keep the colony functioning. But researchers found that some Iberian harvester ant populations have no M. structor colonies nearby.

“That was very, very abnormal. I mean, it was kind of a paradox,” study co-author Jonathan Romiguier, an evolutionary biologist at the University of Montpellier, told Live Science. The team initially believed there was a sampling issue, but they went on to find 69 regions where this was the case.

In setting out to resolve this paradox, Romiguier and his team found that queen Iberian harvester ants also lay eggs containing male M. structor ants, with these males ultimately fathering the workers. This discovery, published Sept. 3 in the journal Nature, is the first time any animal has been recorded producing offspring from another species as part of their normal life cycle.

“In the early stages, it was kind of a joke in the team,” Romiguier said. “But the more we got results, the more it became a hypothesis and not a joke anymore.”

[…]

The team then separated 16 queens from laboratory colonies and looked at the genetic sequences of their freshly laid eggs. They found that 9% of their eggs contained M. structor ants. They then directly observed a single queen producing males of both species by monitoring its broods weekly over an 18-month period.

Together, all these findings show that Iberian harvester ant queens are cloning M. structor males and not passing on any of their own nuclear DNA. Researchers now need to pinpoint the exact mechanism underlying this cloning, Romiguier said, and find out at what point the maternal DNA is removed.