April 15, 2009 -- "Men, who needs them?" is a question sometimes uttered by frustrated women, but a widespread species of tropical ant has taken that position to the extreme by becoming asexual and only producing females, according to a new study. The insect, Mycocepurus smithii, represents the first documented male-less species of ant, the scientists believe. What's more, all of its female ant colonies are thriving on clonal fungi, and appear to have stopped producing males a long time ago, puzzling experts who believe asexuality is evolutionarily disadvantageous. Lead author Anna Himler explained that a life without sex might not be so bad after all. "Sexual reproduction is costly in several ways and asexual reproduction -- the lack of sex -- can be advantageous," she said, offering four reasons. Related Content:
First, "asexuality avoids the energetic cost of producing males, and thus doubles the number of reproductive females produced each generation from 50 percent to 100 percent of offspring," said Himler, a researcher at the University of Arizona's Center for Insect Science. She added there is no need to expend energy trying to find a partner, genes are not broken up, and "the risk of contracting sexually transmitted diseases or parasites" goes out the window. The two main advantages for sexual reproduction, she said, are more effective elimination of deleterious gene mutations and "faster evolution via mixing genes with those of a mate." For the study, published in the latest Proceedings of the Royal Society B, Himler and her colleagues conducted field surveys at hundreds of nests for the ant in Panama, Guyana, Ecuador, Peru, Argentina and Brazil. The scientists failed to find any males. They then collected colonies from five Panama populations of the ant and put them through a barrage of tests. DNA extracted from offspring showed that they were all clones of their mothers. Dissections of colony queens revealed they not only hadn't mated, but their mating apparatus had degenerated, indicating the species has probably been reproducing asexually for a long time. Since certain bacteria can curb sexual activity in insects, the scientists tested for the presence of those, and even administered antibiotics to see if they could "cure" the ants of their no-sex state. Nothing happened. Get More NewsSpiders, Scorpions Among World's Oldest CreaturesMany creepy crawlies have been on Earth much longer than previously believed.Blood-Sucking Vampire Bats Sing DuetsWhite-winged vampire bats "harmonize" with separated roost mates.Oldest Hebrew Writing Possibly FoundAncient inscriptions on a 3,000-year-old pottery shard could make history.Rare, Prehistoric-Age Reptile Found in N.Z.A tuatara has been spotted on the New Zealand mainland for the first time in 200 years.Iceman Has No Living RelativesOetzi, the 5,300 year-old frozen mummy, left no living genetic legacy.SLIDE SHOW: Landscapes of TerrorWhat makes a place feel scary? There are scientific explanations.It's Official: People Are Warming the PolesHumans are conclusively to blame for polar warming, say scientists.Eight-Armed Animal Preceded DinosaursWhat may be one of Earth's first animals was no bigger than a coaster and had eight arms.Phoenicians Live on in People's GenesOne in 17 Mediterranean men may be descended from ancient Phoenicians.Pesticides, Fertilizers Linked to Frog DeclineA pesticide is found to promote parasites among amphibians.Hubble Telescope Taking Photos AgainThe Hubble Space Telescope is once again snapping stunning photos of the universe.Andean Mummy Hairs Show Hallucinogen UseScientists find direct evidence of hallucinogenic drug use among ancient Andeans.Opals on Mars Reveal Planet's Long Wet PastOpals found on Mars suggest the planet has been wet for much longer. |
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