Featured Image Credit: Reef HQ Great Barrier Reef Aquarium
Leonie is a pretty spectacular zebra shark who lives at the Reef HQ Aquarium in Australia, and she’s done something pretty amazing…. almost divine.
Leonie met her male partner Leo in 1999, and they had a successful little family of pups. But then… in 2012, Leo and Leonie were separated, in an attempt by the aquarium to phase out their breeding program for zebra sharks. The tank that she and other females were put into contained no males for that reason.
And everything went well for the next 3 years— until Leonie decided it was time to shake things up.
In early 2016, Leonie laid 41 eggs, which was normal enough— but embryos normally did not form. But then? 4 embryos did form within the eggs, 3 of which hatched into healthy young zebra sharks, all female.
Their names were Cleo, CC, and Gemini.
“There were two possible explanations for Leonie’s eggs hatching,” said Christine Dudgeon, biologist and a co-author of the report on Leonie’s virgin birth. “One was sperm storage, which has been documented in several occasions. Sharks have been known to store sperm from male sharks for extended periods of time.”
Their other theory was parthenogenesis; a form of asexual reproduction where, in a situation with no male for fertilization, the female develops embryos alone. Although asexual reproduction has been recorded in other species of sharks as well, “there are very few reports of asexual reproduction occurring in females with previous sexual histories”, said Dudgeon.
But after genetic testing, their DNA showed only relation to Leonie, rather than any indication of shared genes with her previous mate.
This is an extraordinary feat, but also… it spells hope for the zebra shark species in the wild, which was recently listed as endangered. If this type of parthenogenesis is possible and recorded in captivity, then researchers are hoping that females in the wild, in case of losing suitable mate, will be able to turn to asexual reproduction and carry on the species until their numbers are restored.
To quote the famous line from Jurassic Park’s Ian Malcolm, “Life finds a way.” And that’s exactly what we’re hoping for.