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Monday, January 11, 2010

Asexual Ants

A team of Texan and Brazilian researchers led by Christian Rabeling and Ulrich Mueller have confirmed that fungus-farming Mycocepurus smithii ants reproduce without the benefit of males.

Organisms that lack sexual reproduction can reproduce in a couple of ways. Single celled organisms such as bacteria can split evenly into two daughter cells. Multicellular organisms such as hydras can have offspring by budding. Finally, in some species, embryos can develop without the benefit of fertilization. This process is called parthenogenesis. A surprising example of this occurred in 2001 when a female bonnethead shark gave birth in a Nebraska aquarium after not having had the company of any males.

It can be difficult to determine whether true parthenogenesis has occurred, given the proclivity within some species for the female to store sperm for long periods of time. The scientists in this case dissected the sperm storage organs of reproducing ant queens, and found them to be empty. They also subjected the ants to various stresses (insert footage of lab-coated scientists yelling insults at ants) to see if that induced the queens to produce males. It never did.

The researchers concluded that Mycocepurus smithii simply do not ever have males. This sort of anomaly usually does not last long evolutionarily. Without the benefit of sexual gene mixing, detrimental mutations accumulate. In addition, with much less variability, such species can succumb to parasites or changes in environment.

Photo of Mycocepurus smithii by Erin Prado 6/22/2009 ©,