A group of Amazonian ants have evolved an extremely unusual social system: They are all female and reproduce via cloning. Though their sexual organs have virtually disappeared, they have also gained some extraordinary abilities.University of Arizona biologist Anna Himler originally began studying the ants, called Mycocepurus smithii, because they had incredible success as farmers. Many breeds of ant keep domesticated “farms” where they breed various kinds of fungus for nourishment. But Mycocepurus smithii was able to breed fungus far more successfully, and in greater varieties, than other ants Himler had encountered.
As she and her team studied the insects, they realized there were no male ants anywhere to be found. Himler told the BBC that it’s possible the ants evolved so as “not to operate under the usual constraints of sexual reproduction.” Interestingly, the fungi that the ants cultivate also reproduce asexually. But why would these ants choose to emulate the reproductive cycle favoured by their crops? Himler explains:
“It avoids the energetic cost of producing males, and doubles the number of reproductive females produced each generation from 50% to 100% of the offspring.”
All the members of the colony are clones of the queen. While that means the queen can control every aspect of the population, it also makes the colony vulnerable to pandemics. A virus that can kill one ant can kill all of them, since they all have the exact same immune systems. On the other hand, it seems that a lack of men gave these women more time and energy to cultivate some of the most elaborate forms of ant agriculture ever studied.
According to Himler, ants often evolve highly unusual reproductive strategies. But all-female ant societies are highly rare.