FLORIDA FISH AND WILDLIFE CONSERVATION COMMISSION

A type of asexual reproduction called parthenogenesis, in which an unfertilized egg develops into an embryo, has been observed among some species of birds, sharks, and reptiles in captivity. A report published yesterday (June 1) in Current Biology shows the first genetic evidence of wild-born parthenogenic offspring of a normally sexual vertebrate—the critically endangered smalltooth sawfish (Pristis pectinata).

“We were conducting routine DNA fingerprinting of the sawfish found in this area in order to see if relatives were often reproducing with relatives due to their small population size,” study coauthor Andrew Fields, a graduate student at Stony Brook University, said in a statement. “What the DNA fingerprints told us was altogether more surprising: female sawfish are sometimes reproducing without even mating.”

Fields and his colleagues conducted DNA fingerprinting on 190 smalltooth sawfish sampled in southwest Florida between 2004 and 2013. The...