The Birds and The Bees, and the Smalltooth Sawfish?

Turns out that reproduction twist from Jurassic Park isn’t so far-fetched after all. When animals face extinction, life finds a way.

Researchers studying the critically endangered smalltooth sawfish in an estuary in Florida were looking for evidence of inbreeding and found instead the first instance of asexual breeding occurring in the wild. Through a process known as “virgin birth,” females can fertilize their eggs without sperm.

In a study published in the journal Current Biology, the researchers reported that they found seven small, immature sawfish that appeared to have been created through asexual means. According to National Geographic, lead author Andrew Fields, a geneticist at Stony Brook University in New York, found the evidence for the virgin births by accident while looking through a database of 190 smalltooth sawfishes tagged in southwestern Florida between 2004 and 2013. It was there that he realized seven of the sawfishes’ genes suggested they had only one parent.

Sawfish snout from above. (Photo Florida Fish and Wildlife Conservation Commission)
Sawfish snout from above. (Photo Florida Fish and Wildlife Conservation Commission)

Professor Fields isn’t sure whether virgin births are more common among wild animal populations than researchers think. Fields said of questions remain, such as, “is this a special case because we have an endangered species with very few individuals and they don’t run into each other, or is it because they’re sawfish and sawfish have something interesting going on?”

While remarkable, virgin births (also known as parthenogenesis) isn’t unheard of in snakes, birds, or sharks. But the team’s discovery marks the first time that virgin births have been documented in the wild in members of the shark family.

Back in 2012, an 11-year-old reticulated python named Thelma produced six babies while living at the Louisville Zoo in Kentucky with another female python. Neither ever had contact with a male python. DNA evidence, published in July in the Biological Journal of the Linnean Society, revealed that Thelma is the sole parent.

There are some species of whiptail lizards in the American Southwest and Mexico who sometimes exhibit parthenogenesis; in these species, every single lizard is female.

To date, there have been no known instances of parthenogenetic mammals in the wild, or occurring naturally at all.

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