Virgin birth not just a by-product of captivity

By Susan Milius

Web edition: September 12, 2012
Print edition: October 20, 2012; Vol.182 #8 (p. 16)

Snakes in the wild sometimes forgo the mom-and-dad method of reproducing and have babies without having sex, researchers have confirmed with genetic testing.

Occasional no-sex reproduction has been seen in captivity among snakes, Komodo dragons and sharks. But until now there has been no conclusive evidence for wild virgin birth among species that normally reproduce sexually, says Warren Booth of the University of Tulsa in Oklahoma. (In about 80 kinds of vertebrates, a single sex carries on the species quite well on its own.)

Booth and his colleagues examined dozens of litters of wild-caught copperheads and cottonmouths. The team found one case in each species of a male baby born without littermates. Genetic testing showed that these babies’ maternal and apparently paternal DNA was identical at multiple locations, making the chances that a daddy snake actually was involved in the reproductive process vanishingly small. The researchers report their findings online September 12 in Biology Letters.