Mutant, Parasitic Impostor Queens Lurk in Ant Colonies

Mutant, Parasitic Impostor Queens Lurk in Ant Colonies
Mutant, Parasitic Impostor Queens Lurk in Ant Colonies

An undated picture supplied by Trible et al., Present Biology 2023 of a typical clonal raider ant, left, and a queenlike mutant with the supergene. (Trible et al., Present Biology 2023 through The New York Instances)

To thrive, ant colonies depend on everybody pulling their weight. For raider ants, this implies diligent scouts observe down different nests, then direct a whole lot of savage foragers to assault. They return with pincers gripping useless younger ants to feed the settlement. Clones are produced. The colony thrives.

However raider ants are amongst about 50 species stricken by impostors: parasitic ants that resemble queens. They greedily eat the colony’s meals, however shirk their very own foraging duties, and may solely hatch extra parasites as a substitute of employees once they reproduce. How the faux queens emerge has lengthy puzzled scientists.

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“It’s an actual thriller how these items arrive,” mentioned Ken Ross, an evolutionary geneticist on the College of Georgia.

A examine printed Tuesday in Present Biology gives an answer. A “supergene” that mutates quickly, between a single technology of raider ants, is probably going chargeable for the royal impostors. The invention arose from a stunning commentary in a lab at Rockefeller College, the place Waring Trible and his graduate adviser, Daniel Kronauer, studied colonies of raider ants.

“These bizarre, mutant queens simply confirmed up,” mentioned Trible, now at Harvard, who led the examine. Remoted from the remainder of the colony in a petri dish, it was plain to see: A number of of the ants had wings.

It’s a typical trait for queens in many species, but it surely was odd as a result of raider ants don’t usually have wings, or queens.

“Seeing these winged females was very stunning, very putting, immediately,” Trible mentioned. “I instantly thought it was one thing genetic.”

He set about sorting by way of the ten,000-ant colony. His needle-in-a-haystack search discovered a complete of 14 impostor queens, which he then let reproduce. Their progeny have been all the time the winged parasites.

Trible and his colleagues devoted years to finding out the mutants and attempting to determine their origin. One other geneticist, Sean McKenzie, compiled the common ants’ entire genome, whereas Trible analyzed the mutants’ genome. Evaluating the genomes let Trible see the place the common and mutant ants differed.

In each sorts of ants, one chromosome carries a set of genes which can be all inherited collectively and may management vital traits and capabilities, often known as a supergene. Common ants have one copy of the supergene and one other model that’s mutated and recessive. However the impostor queens have two copies of the mutated supergene.

“Such a mutation in people would seemingly kill you,” Trible mentioned. “The chromosome is so degenerated. It’s a extremely nasty mutation.”

However for these ants, what doesn’t kill them makes them develop wings.

It’s “overwhelmingly seemingly” that the supergene controls the expansion of impostor queens, however extra focused analysis is required to substantiate the discovering, Trible mentioned.

For many years, the widespread considering was that advanced traits or behaviors, equivalent to parasitism or the variety of queens in a colony has, can be decided by the mixed affect of many genes, mentioned Ross, who found the primary supergene in ants and wasn’t concerned in the brand new examine. However scientists now know, he mentioned, that “there could also be numerous genes, however they are usually locked up in supergenes.” Which means advanced traits can rely upon only a single issue, “which is simply superb,” he mentioned.

Whereas scientists have recognized at the very least 5 different ant supergenes, this might be the primary to manage caste, or whether or not ants develop into employees, foragers or queens; the others have been tied to social conduct. Why ants grow to be adults of a sure caste is an open query. This supergene seems to have eliminated the parasites’ capacity to be employees and permits them to play a task not usually discovered in the raider species.

“Isolating a caste-based mutant is a extremely highly effective device,” Trible mentioned. Mutants, he mentioned, could be an vital window into the in any other case black bins of evolution.

That is additionally the primary time parasitic ants of the identical species as their host have been noticed. Whereas there are various parasitic ants, till now they’ve been a separate species from their host, maybe evolving slowly over time from the unique species to develop into their parasite. The brand new examine reveals {that a} parasitic mutation can happen inside a species and throughout a single technology, upending earlier hypotheses that such transitions take 1000’s of years or longer.

“It was a single step, but it surely wasn’t trivial,” Ross mentioned.

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