In most ants, colonies consist of one or several queens and many workers. The queens take care of reproducing, while the workers…work. These workers are mostly sterile, unable to mate and lay eggs.
However, in some primitive ants, such as Diacamma, all individuals are born with fully working reproductive parts, but only one these individuals acts like a queen (although scientists call her ‘gamergate’ instead of queen, as she was originally a worker). Unfortunately for the rest of the workers, this gamergate wants to be the only one that does the reproducing, as the others should work!
Diacamma worker. Picture by Alex Wild
How does she make sure the rest of the workers don’t reproduce? Well, fertility in these ants is governed by bladder-like structures growing out of their body called gemmae. When a young ant comes out of its pupa, she will soon be grabbed by her legs and held down by a couple of her sisters so she can’t move. Afterwards, the gamergate comes in and mutilates the poor worker, biting off her gemmae, ensuring that she will just work and will never reproduce.
Scanning Electron Microscope picture of part of a Diacamma ant. I indicated where the gemmae are. Picture adapted from Peeters & Higashi (1989) Naturwisseschaften
This ensures that there will always be only one reproducing individual. If she dies, the first worker to come out of the pupa after that does not get mutilated, and will immediately start mutilating all the workers that get born after her, and become the new gamergate.
Such is the game of ant-thrones.
Source: Peeters & Higashi (1989) Reproductive dominance controlled by mutilation in the queenless ant Diacamma australe. Naturwissenschaften 76:177-180
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