One ant species has given up sex completely

Washington, Aug 26 (ANI): Texas and Brazilian researchers have confirmed the complete asexuality of a widespread fungus-gardening ant-called Mycocepurus smithii- the only ant species in the world known to have dispensed with males entirely.

Most social insects-the wasps, ants and bees-are relatively used to daily life without males with their colonies being run by swarms of sterile sisters lorded over by an egg-laying queen.

However, eventually, all social insect species have the ability to produce a crop of males who go forth in the world to fertilize new queens and propagate.

According to Christian Rabeling, Ulrich Mueller and their Brazilian colleagues, queens of the ant Mycocepurus smithii reproduce without fertilization and males appear to be completely absent.

"Animals that are completely asexual are relatively rare, which makes this is a very interesting ant.

Asexual species don't mix their genes through recombination, so you expect harmful mutations to accumulate over time and for the species to go extinct more quickly than others. They don't generally persist for very long over evolutionary time," said Rabeling.

Earlier studies on the ants from Puerto Rico and Panama have pointed toward them being completely asexual.

One particular study showed that the ants reproduced in the lab without males, and that no amount of stress induced the production of males.

Scientists believed that specimens of male ants previously collected in Brazil in the 1960s could be males of M. smithii, but if males of the species existed, it would suggest that-at least from time to time-the ants reproduce sexually.

The researchers analysed the males in question and discovered that they belonged to another closely related (sexually reproducing) species of fungus-farmer, Mycocepurus obsoletus, thus establishing that no males are known to exist for M. smithii.

They also dissected reproducing M. smithii queens from Brazil and found that their sperm storage organs were empty.

Overall comparison made the researchers to conclude that the species is very likely to be totally asexual across its entire range, from Northern Mexico through Central America to Brazil, including some Caribbean islands.

As for the age of the species, the scientists have estimated that the ants could have first evolved within the last one to two million years, a very young species given that the fungus-farming ants evolved 50 million years ago.

Rabeling said that he is using genetic markers to study the evolution and systematics of the fungus-gardening ants and this will help determine the date of the appearance and genetic mechanism of asexual reproduction more precisely in the near future.

The study has been published in PLoS ONE. (ANI)