In 1998, a copperhead snake (Agkistrodon contortrix) was collected on the Konza Prairie in Kansas for observation. After three years in isolation, the female pit viper gave birth to a pair of female offspring via parthenogenesis, a process whereby a female animal gives birth without having her eggs fertilized by a male. Kansas State University Assistant Professor of Biology Eva Horne had been keeping tabs on the mother and the surviving offspring. The babies were totally unexpected and Horne was initially surprised when she learned the babies gave birth. "I thought the person who told me about the babies was joking because the cage was locked and no one could have added the snakes," Horne said. "I haven’t ever housed her with a male and don’t know if there are some environmental cues required for parthenogenic reproduction that are missing in captivity. She has only had one litter in captivity."
Horne reported her findings to Kansas State University Biology Professor Susan Brown, who two years ago started her investigation of the genetic markers of the snakes. Brown, along with Tony Grace, a Kansas State post doctoral research associate, studied the molecular markers of the three snakes and conducted tests on the snakes using the markers and determined that the offspring were exact clones of the mother snake. "The offspring are genetically identical to their mother, but the scale patterns are different, Horne told ReptileChannel. "This is similar to identical twins in humans having slight differences in appearance and mannerisms and has to do with how and when the genes are expressed. "
Brown told The Topeka Capital Journal that the mother and babies were identical, so they were clones of the mother. Brown and her team then concluded that the female copperhead was the parent and the reproduction was the result of parthenogenesis and was not the result of sperm storage, a process where the female stores viable sperm in her body for up to six months. While the copperhead was able to reproduce in captivity via parthenogenesis, the scientists do not know if the copperhead indeed reproduces via parthenogenesis in the wild. The next step in the study is to collect pregnant female copperheads in the wild to determine if the snakes became gravid via parthenogenesis or via a male copperhead snake.
Other reptiles are known to reproduce via parthenogenesis, including the Komodo dragon (Varanus komodoensis), New Mexico whiptail lizard (Cnemidophorus neomexicanus), certain geckos and certain boa constrictors.