In the spring ants are once again hard at work. Beyond their everyday presence, ants are also key model organisms in cutting-edge evolutionary genetics research, helping scientists understand how social behavior and cooperation evolve.
New research from the University of Oulu, Finland reveals surprising insights into the evolution of ant societies. Two recent studies show that colonies with multiple queens can arise from different genetic mechanisms—and may even persist after the genomic region previously linked to this social structure has completely disappeared.
Many ant species can organize their societies in two distinct ways: colonies may have either a single reproductive queen or multiple queens—sometimes even hundreds. Researchers investigated the genetic basis of these social systems in two groups of ants: furrowed ants of the genus Myrmica and wood ants of the genus Formica, which are both found widely in Eurasia.
In the species
Myrmica ruginodis, colonies are typically found in forested areas beneath moss-covered ground. Some colonies have a single queen, which produces large daughters capable of dispersing and founding new colonies. Other colonies contain multiple queens which instead produce smaller queens that remain in their natal nest and reproduce there.
The researchers found that both queen size and number of queens per colony are determined by previously unknown supergene—a large block of DNA containing hundreds of genes that are inherited together.
“It’s interesting how evolution keeps finding similar genetic solutions in ants”, says lead author
Hanna Sigeman. “Supergenes have independently evolved in different species to control similar social traits, and each new example helps us narrow down which genes are important for shaping ant societies.”
Wood ants, on the other hand, are known for building the large, familiar ant mounds seen in forests. They can form vast supercolonies, where dozens of nests are interconnected by networks of ant trails.
When studying wood ants, researchers encountered an unexpected finding. A previously known and evolutionarily ancient supergene associated with multiple-queen colonies had completely disappeared in two species—yet these colonies still contained hundreds of reproducing queens.
“We were puzzled by how multiple queens could still coexist when the supergene thought to enable this had been lost,” says University Lecturer
Lumi Viljakainen, who led the research group. “At the same time, we found that two individual genes previously located within that supergene had been relocated elsewhere in the genome.” These genes are thought to still play a role in allowing multiple queens to be accepted within the same colony.
The studies deepen our understanding of the genetic foundations and evolution of social behavior. Findings suggest that evolution can also dismantle complex genetic systems such as supergenes. “A gene complex that was once beneficial may later become a burden, for example due to the accumulation of harmful mutations,” Viljakainen explains. “Our results also show that complex social traits can persist even when their genetic basis changes. Evolution is not a single linear path—it often finds multiple solutions to the same problem.”
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