Ants may be held up as ideals of social co-operation but they can be as sneaky as humans beings and their colonies are rife with corruption – with those from the royal line the worst offenders.

DNA fingerprinting techniques have shown that nepotism rules when it comes to determining which larvae grow up to be queens.

It had been thought that this was purely a matter of luck, but researchers have found that a larvae’s chances of becoming queen largely depend on who was its father. A handful of breeding males pass on a genetic advantage that give their offspring a much better chance of growing up into a queen instead of being condemned to a life of drudgery as a worker.

The finding overturns the widely held assumption that ants work equally for the benefit of the whole colony instead of the selfish promotion of their own individual genes.

William Hughes, of the University of Leeds, who led the research, said: “The core principle of social societies is they should be egalitarian. We’ve found this isn’t always the case and that some of the males are cheating. There is a genetic influence on royalty.”

Until the study identified the inherited advantage, it had been thought that queens were produced solely by nurture, with some larvae being fed special or extra food to help their development. “It had been thought all larvae could have that opportunity,” Dr Hughes added, “But we carried out DNA fingerprinting on five colonies of leaf-cutting ants and discovered that the offspring of some fathers are more likely to become queens.

“These ants have a ‘royal’ gene or genes, giving them an unfair advantage and enabling them to cheat many of their altruistic sisters out of their chance to become a queen themselves.”

The mechanism by which male ants are able to pass an unfair advantage to their offspring remains unclear, but researchers believe they must limit themselves intentionally.

If too many larvae grew into queens it could upset the balance of the colony, reducing its survival prospects. Moreover, the imbalance would probably be noticed by the “commoner” workers, who might kill the surplus.

Queen leaf-cutter ants undergo multiple matings and are able to store sperm all their lives. It is thought that males passing on the “royal gene” to their offspring mate with lots of females but provide only a small quantity of sperm each time. This way they have lots of offspring but spread though several colonies.

Dr Hughes added: “The most likely explanation has to be that the ants are deliberately taking steps to avoid detection. The rarity of the royal lines is actually an evolutionary strategy by the cheats to escape suppression by the altruistic masses that they exploit.”

Dr Hughes and Professor Jacobus Boomsma, of the University of Copenhagen, said the royal gene discovery, published in the journal Proceedings of the National Academy of Sciences, debunks the notion of unadulterated egalitarian cooperation within ant colonies.

“When studying social insects like ants and bees, it’s often the cooperative aspect of their society that first stands out,” he said.

“However, when you look more deeply, you can see there is conflict and cheating – and obviously human society is also a prime example of this. It was thought that ants were an exception, but our genetic analysis has shown that their society is also rife with corruption – and it’s royal corruption at that.”

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