Red fire ants, known as “invincibles,” evolved a million years ago from having just one queen to accepting multiple at once. Then, they passed on that “super gene” to other species. Scientists hope that these discoveries will help understand evolutionary processes.
Scientists from the Queen Mary University of London have discovered that the red fire ants they helped other species of this insect to evolve a new form of society a million years ago, by passing on a “supergene” that gives them more chances of survival.
Often referred to as ‘invincible’ because of their invasiveness, these ants originally only had colonies with one queen. However, the team found in previous research that a million years ago they evolved the new form of organization, in which colonies could have dozens of queens.
This spread occurred through hybridization, that is, reproduction between ants of different species. This unlikely event provides an alternative way of life, making the ants more successful than if they just had the original social form.
One particular version of a large part of the chromosome, called a “social supergene,” includes the genetic information necessary for workers to accept more than one queen.
The new research, published in Nature Communications, analyzed the complete genomes, or instruction sets, of 365 male fire ants to examine the evolution of the social super gene and found that the same version of this chromosome is present in multiple fire ant species.
Transfer of large amounts of genetic information between species is rare due to genetic incompatibilities. In this case, however, the advantages of having multiple queens overrode the incompatibilities, and the genetic material repeatedly spread to other species from the parent species in which this new social form evolved.
The social form of multiple queens has advantages in several situations. For example, a multi-queen colony has more workers and therefore can outcompete a single-queen colony. Also, if there is a flood, a colony with multiple queens is less likely to be queenless.
The Dr Yannick Wurm, Reader in Evolutionary Genomics and Bioinformatics at Queen Mary University of London and fellow at the Alan Turing Institute, said in a statement: “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 hybridization. The supergene region that creates multiqueen colonies is a large piece of chromosome that contains hundreds of genes. The many parts of a genome evolve to work together in a fine-tuned way, so suddenly having a mix with different versions of many genes from another species is complicated and quite rare,” she added.
Now, the scientists hope to identify which genes drive these behavioral changes, which they hope will help “fill more gaps in our understanding of evolutionary processes.”
Rodrigo Pracana, lead author of the studyalso from Queen Mary University of London, added: “Our study shows how detailed analysis of large numbers of wild animals can provide surprising new insights into how evolution works.”
The Queen Mary team was previously among the first in the world to apply large-scale DNA sequencing approaches to wild insects, allowing them to discover one of the first known super genes.
Red fire ants are native to South America and are famous for their painful stings. One of these species is known from many other parts of the world, where its aggressiveness and high population density have made it an invasive pest.
Efforts to control the spread of this species have been largely unsuccessful, as indicated by its Latin name, Solenopsis invicta, meaning “the invincible one.”