"It's a selfish strategy initiated by females [in which] queens transmit 100 percent of their genome," Fournier said.
Instead of simply being cut out as evolutionary actors, however, male fire ants hit back. They also reproduce themselves clonally and pursue their own genetic lineage. Researchers suggest that male genomes are eliminating female genomes in fertilized eggs, making the eggs functional clones of the males.
"Males would normally die off, but in this system they were retained only so that diverse sexual workers could be produced," said Queller, who wrote an accompanying commentary for the Nature study. "This apparently gave males both the time and the means to evolve a counterattack—converting some of the workers into males."
Scientists hypothesize that genetic diversity in an ant colony is important for defending against parasites, as well as adapting to changes in environmental conditions.
"From an evolutionary point of view, this discovery concretely indicates that genetic variability is the major advantage of sexual reproduction and illustrates the extraordinary imagination of nature—or of the male ants—to counteract this female strategy," Fournier said.
While males and females remain affiliated by the mutual production of workers, the sexual conflict between the two could ultimately lead to each sex becoming its own species.
"I think if further work confirms that there is little or no gene exchange between males and females, we really might consider them to be separate species," Queller said. "It is odd that they are completely dependent upon each other. But then so are many other mutualistic pairs of species."
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