We are accustomed to perceiving evolution as a progressive process that provides each living being with the best adaptation to the conditions of its existence. However, not everything is as straightforward as it seems. An example of this is the tree turtle ants or cephalottes (Cephalotes).
In an article published in the journal Proceedings of the National Academy of Sciences (PNAS), scientists from Rockefeller University (USA) reported on the results of studies of the cephalott caste system. They paid special attention to the evolutionary changes that the soldier ants of this species are currently undergoing.
Among their relatives, they are distinguished by an unusual head shape: in some it resembles a sewer manhole, while in others it has an almost square shape. The key task of the soldiers in the community is to reliably close the entrance to the anthill with their heads in case of danger. In total, scientists know four morphotypes characteristic of turtle ants.
This variety of shapes helps scientists understand how species evolve as they fill ecological niches. It is worth clarifying that turtle ants do not build anthills, but occupy tree chambers eaten by lumberjack beetles.
The shape and size of the head of the soldiers of a particular colony is formed depending on the shape and size of the entrance to it. Since the entrance can be of the most unusual configuration, heads of a variety of configurations will be required to securely seal it.
The researchers analyzed 89 species of turtle ants, including a group with no soldiers at all, and concluded that their distant ancestor appeared to have a square head. Further, in the process of evolution, several species came from it with different shapes and sizes of heads.
“This finding perfectly shows how amazingly flexible nature can be, adapting the shape of an organism to the characteristics of the environment in which it lives, ” said co-lead Scott Powell.