How fire ants’ ‘supergene’ helps them survive

By Gwyn Wright via SWNS

A social 'supergene' that makes colonies of fire ants bigger and more numerous has been discovered by scientists.

Researchers identified the special gene which tells red fire ants to accept more than one queen, who is the mother of all the ants in that colony.

Having more than one queen makes ant colonies bigger and means they are more likely to survive a natural disaster such as a flood when they could lose their queen.

The new colony structure evolved in red fire ants around one million years ago but spread to other types of fire ants through breeding.

This unlikely event made the ants more successful, but also more of a nuisance for humans than they would have otherwise been.

Fire ants are infamous for their aggressiveness and extremely painful sting.

Efforts at controlling the spread of red fire ants, which are native to South America, have largely been unsuccessful, as indicated by its Latin name, Solenopsis invicta, meaning “the invincible”.

Researchers at Queen Mary University of London had already discovered that around one million years ago, a new type of red fire ant colony emerged with multiple queens.

A particular version of a large section of the chromosome, called the ‘social supergene’ contains genetic instructions that make the ant workers accept more than one queen.

The research team has now discovered that the same version of this chromosome exists in many types of fire ants.

They found this out by analyzing the entire genomes or instruction sets of 365 male fire ants.

The transfer of large amounts of genetic information across species is usually rare because the genes are not compatible.

In this case, the advantages of having multiple queens outweighed the drawbacks.

Study author Dr. Yannick Wurm said: “This research reveals how evolutionary innovations can spread across species.

“It also shows how evolution works at the level of DNA and chromosomes.

“It was incredibly surprising to discover that other species could acquire a new form of social organization through breeding.

“The supergene region that creates multi-queen colonies is a large piece of chromosome that contains hundreds of genes.

“The many parts of a genome evolve to work together in fine-tuned manners, thus suddenly having a mix with different versions of many genes from another species is complicated and quite rare.

“Instead of executing extra queens as they would in a single-queen colony, the new version of the supergene leads workers to accept multiple queens.

“Having studied the history of the supergene and new social form extensively, we next want to identify which genes or parts of the supergene region, lead to these changes in behavior.

“This will also help fill more gaps in our understanding of evolutionary processes.”

Lead study author Dr Rodrigo Pracana said: “Our study shows how detailed analysis of large numbers of wild animals can provide surprising new insight on how evolution works.”

The findings were published in the journal Nature Communications.