First ‘virgin births’ recorded in the wild

Scientists have recorded the first “virgin births” in wild animals that normally reproduce sexually.

Scientists have found seven juvenile smalltooth sawfish spawned through a natural phenomenon of immaculate conception known as parthenogenesis. Picture: Florida Fish and Wildlife Conservation Commission.

Scientists have recorded the first “virgin births” in wild animals that normally reproduce sexually, in what could be a last-ditch ­evolutionary strategy to avoid ­extinction.

DNA tests on seven endangered rays, known as smalltooth sawfish, have revealed they were conceived asexually through parthenogenesis.

The species, which grows up to 7m long and has up to 58 teeth around a long flat snout, was once common in southern US waters. Now it is restricted to the Everglades at Florida’s tip and a handful of other Atlantic sites.

Andrew Fields, a doctoral student at Stony Brook University in New York, said his team had been conducting routine DNA analysis of Florida sawfish to find out whether population pressure had forced the creatures to mate with relatives. “What the DNA fingerprints told us was altogether more surprising: female sawfish are sometimes reproducing without even mating,” he said.

The discovery, reported today in Current Biology, ­follows reports of parthenogenesis involving some birds, snakes and sharks — but only in captivity.

The journal said parthenogenesis was common in invertebrates but rare in animals with ­backbones. It said vertebrate parthenogenesis was thought to occur when an unfertilised egg absorbed a genetically identical sister cell. “The resulting offspring have about half of the genetic diversity of their mothers, and often die.”

Co-author Gregg Poulakis said vertebrate parthenogenesis had been considered a curiosity that was unlikely to spawn viable offspring. But the seven rays in the study appeared to all be in perfect health. The journal said parthenogenesis could help keep the sawfish going “a little longer. But it won’t be enough to save them”.