We humans have Tinder, Hinge, eHarmony, and Grindr. For other animals, there is a real shortage of matchmaking services, not even Bumble or Plenty of Fish.
But for future queens of an ant species, sterile worker ants seem to fulfill this function by physically transporting their royal sisters to nearby nests. There, future queens can mate with unrelated male ants, according to researchers in a study published this month in Communications Biology.
“It’s pretty exciting,” said Jürgen Heinze, zoologist at the University of Regensburg in Germany and co-author of the study. “This is the first case of this choice of assisted companion and of the assisted inbreeding that we have in animals.”
If you look at the ground near the shores of the Mediterranean, you might sometimes catch a glimpse of the sun reflecting off the wing of a Cardiocondyla elegans. queen ant. But the queen probably wouldn’t fly, or even walk. Instead, she would ride on a worker ant, gripped tightly by a worker’s mandibles.
“Once you’ve looked for these colonies and the carrying behavior a lot, when you close your eyes in the evening you only see these little ants moving around,” said Mathilde Vidal, doctoral student in Regensburg and lead author of the study. .
From 2014 to 2019, researchers mapped the location of 175 Cardiocondyla ant colonies in the south of France and recorded 453 cases of this carrying behavior.
Although these workers are tiny – only 2 to 3 millimeters in length – they have been observed carrying queens up to 15 meters from their homes before depositing their sisters at the entrance of a foreign nest. And the workers seemed to know where to take their sisters, traveling more or less in a straight line and jumping from closer nests. Genetic experiments have shown that the ants in the nests chosen by the workers were less genetically linked.
As with all sexually reproducing organisms, choosing the right mating partner is an important decision for Cardiocondyla elegans. But this particular species faces a particular problem: Male ants have lost their wings and remain trapped in “mating chambers” near the entrance to the nest where they regularly mate with related females. (Genetic data shows that more than ⅔ of all matings in Cardiocondyla involve close relatives.)
Excessive inbreeding can be detrimental. In a 2006 study, Dr Heinze and colleagues found that prolonged inbreeding in another species of Cardiocondyla led to unhealthy ant colonies: shorter lifespan for the queen, higher mortality of offspring, modification sex relationships.
Most ant species counteract this with inbreeding through mating flights – spectacular one-day events in which winged queens and males from many different colonies congregate, swarm and mate in large clouds. . But the queens Cardiocondyla elegans need help.
There is also evidence that at least some young queens are carried from one nest to another, potentially mating with males from multiple colonies. No young queen ever returns to her native nest, instead spending the winter in a foreign nest. In the spring she is expelled – there can only be one laying queen per nest – and presumably begins her own colony, starting the cycle again.
There is only one mating season for these young queens, but it is more than enough. A queen stores and keeps her mate’s sperm in a bag called a spermatheca for the rest of her life. In some species, only two sperm are needed to fertilize an egg and that’s all the queen releases (a little more efficient than the 40 to 150 million sperm that humans use to accomplish a similar task).
Although the traditional social society view of insects has held that the Queen wields all power over the faceless workers beneath her, research increasingly shows that is not the case, Boris Baer said, Entomologist at the University of California at Riverside. And this new research provides yet another example.
“It seems that the workers have taken into their own hands what power they hold in these companies and are making decisions regarding the mating of their sisters,” said Dr Baer, who was not involved. in the study.
Yet a big mystery remains: “We have no idea how they choose a specific colony,” said Dr Baer.
So far, researchers have not been able to obtain ants they collected to perform transport behavior in a controlled laboratory. Yet the new research highlights the various ways that living things in general and ants in particular reproduce in our world.
“Everywhere I go and find a new species of Cardiocondyla, they have a different mating system, they have a different colony structure, they have different ways of dispersing,” Dr. Heinze said.