April 15, 2009

Scientists Discover Asexual Female Ant Colony

A species of tropical ant appears to have done away with sex altogether. Instead, the ants now only produce females through a process of cloning.

These Mycocepurus smithii ant species have been discovered as the first ever to reproduce without sex, said researchers in the journal Proceedings of the Royal Society B.

Anna Himler, a biologist from the University of Arizona's Center for Insect Science led the study in which researchers used "fingerprinting" DNA to show that each ant was in fact a female clone of the queen.

Upon further investigation, Himler and colleagues discovered that the female ants were physically unable to mate due to a missing "mussel organ," which is essential for breeding.

This asexual form of breeding is extremely rare among female ants, researchers said.

"In social insects, there are a number of different types of reproduction," said Dr Himler. "But this species has evolved its own unusual mode."

Her team is unable to tell why, and at what point in history the ants began to reproduce asexually. Future investigations will be aimed to providing more answers to those questions.

Dr. Himler explained that there are advantages to the ants' unusual method of reproduction.

"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."

"If we're more diverse, we're more resistant to parasites and disease," Laurent Keller, an expert in social insects from the University of Lausanne, told BBC News.

"In a colony of clones, if one ant is susceptible to a parasite, they will all be susceptible. So if you're asexual, you normally don't last very long.

"But in ants we're seeing more and more reports of unusual methods of reproduction," added Professor Keller, who was not involved in this study.

"When we started to study this species more closely, we just weren't finding any males. That's when we started to look at them in a different way," said Dr. Himler.

Image Courtesy California Academy of Sciences


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