These fish have suddenly started having virgin births

Juvenile smalltooth sawfish inthe Charlotte Harbor estuarine system, Florida. Image: Florida Fish and Wildlife Conservation Commission.

Female smalltooth sawfish, an endangered species of ray, are giving birth despite never having known a male, say US scientists who looked at their genetic code.

The virgin births, which make up around 3% of sawfish offspring, are the first recorded in a wild animal which generally reproduces normally.

Earlier evidence that vertebrates might sometimes reproduce via a process called parthenogenesis came from isolated examples of captive animals, including birds, reptiles and sharks.

The animals surprised their keepers by giving birth despite the fact that they’d had no opportunity to mate.

The latest discovery is reported in the journal Current Biology by Demian Chapman of Stony Brook University in New York and his colleagues from the Priztker Laboratory at the Field Museum of Chicago and Florida Fish and Wildlife Conservation Commission.

The find was made after conducting routine DNA fingerprinting of smalltooth sawfish in a Florida estuary.

The researchers say that smalltooth sawfish could be the first family of marine animals to be driven to extinction due to overfishing and coastal habitat loss.

“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,” says lead author of the study, Andrew Fields at the Stony Brook University’s School of Marine and Atmospheric Science.

“What the DNA fingerprints told us was altogether more surprising: female sawfish are sometimes reproducing without even mating.”

For smalltooth sawfish, it’s possible this ability could keep them going for a little longer. But it won’t be enough to save them, say the researchers.

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