Division of labor in ants goes back over 100 million years

Ants live in states organised according to the division of tasks. There are three castes, each of which has a different role: the queen lays eggs and the males fertilise them, while the workers look after the offspring and deal with finding food and nest-building. In biology, this special behaviour is called eusociality, which is developed in a particularly complex way in ants, as it is shown not only in their behaviour, but also in their morphology.

Winged females take on the role of the queen, while wingless, infertile females perform the tasks of the workers. But when exactly in their evolution did ants start this unique teamwork? The research team has now established that this cooperative way of life developed in the early Cretaceous period and the scientists present their findings in the research journal Zoological Journal of the Linnean Society.

Ant pupa found in Cretaceous amber for the first time
In their work, the biologists closely examined four fossils enclosed in amber. These were three adult female wingless ants and one incompletely developed pupa - the first ant pupa ever found in Cretaceous amber. "With the help of micro-computed tomography images, we were able to determine that the soft tissues of the insects have been exceptionally well-preserved," explains Dr Brendon E. Boudinot, who is currently working at the University of Jena under a Humboldt Research Fellowship.

"This enabled us to examine the precise structure of the brain and the transverse muscle fibres, for example, and thus compare the four specimens with each other in fine detail."

Sensational discoveries
Based on these insights into the ants' internal anatomy, the researchers were able to draw conclusions about the species - and in doing so to make two spectacular discoveries. First, they established that two of the adult insects belong to a previously unknown species of the extinct ant genus Gerontoformica, which the biologists have now been able to describe more precisely for the first time.

Second, the third adult ant and the pupa are both of the same species: Gerontoformica gracilis.

"As ant pupae are not mobile, it can be inferred that the adult insect carried it," says US entomologist Boudinot. "This brood transport, as it's called, is a unique feature of ant coexistence based on their division of labour. The fossil therefore provides the first material evidence of cooperative behaviour from the Cretaceous period: these ants looked after their young together, went in search of food together and had different queen and worker castes."

The fossil representatives of the extinct ant genus are therefore an important "missing link" between today's ants and their closest relatives, confirming that the specialised social system of ants evolved sometime in the early Cretaceous - during the time of the dinosaurs.

New insights into the evolution of ants
The work on the four fossil ants has shown the researchers the wealth of information that can be produced using the high-resolution imaging facilities. "We can now derive new insights into the development of the internal anatomy of fossil insects and clarify much more precisely the relationships of fossil species to each other and to species living today," says Boudinot. For example, how did the two different female forms of ants - queens and workers - develop?

Did the wings regress first and then fertility, did the onset of sterility lead to the loss of the wings or did both developments take place at the same time? Thanks to the new findings and methods, scientists may soon be able to provide answers to such questions about the evolution of ants. There are also new, connected, research questions in the field of sociobiology, for example on the emergence of eusociality.

Research Report: "Evidence for the evolution of eusociality in stem ants and a systematic revision of !Gerontoformica (Hymenoptera: Formicidae)"

Related Links
University of Jena
Explore The Early Earth at TerraDaily.com

Tweet

Thanks for being there;
We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain.

With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords.

Our news coverage takes time and effort to publish 365 days a year.

If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.

SpaceDaily Monthly Supporter
$5+ Billed Monthly

paypal only

SpaceDaily Contributor
$5 Billed Once

credit card or paypal

'Exceedingly rare' intact pterosaur fossil from Jurassic period found in Scotland
Washington DC (UPI) Feb 22, 2021
Researchers in Scotland said a winged reptile fossil found on one of the country's islands is a previously unknown type of pterosaur and the largest ever discovered from the Jurassic period. The University of Edinburgh team, which published its paper on the discovery Tuesday in the journal Current Biology, said the pterosaur that lived about 170 million years ago was remarkably well-preserved when it was discovered in 2017 on the Isle of Skye, off Scotland's west coast. "Pterosaurs prese ... read more