Miracle in Louisville? Virgin Python Gives Birth to Clone Babies

The babies are the mother snake's clones, the Louisville Zoo has confirmed with the help of the University of Tulsa.

Ruth Schuster
Ruth Schuster
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Thelma the python
Thelma the pythonCredit: Louisville Zoo
Ruth Schuster
Ruth Schuster

A reticulated python in Kentucky is the first of her species known to produce a virgin birth. The lucky snake, named Thelma, had six daughters, all perfect clones of herself at the Louisville Zoo, where she lives with another python named, of course, Louise.

Although the initial assumption had been that the python stored sperm, it isn't so, says the zoo: it's confident that the 20-foot long female had no contact with male snakes.

Thelma, 11, had never given birth during her four years at the Louisville Zoo, the facility's spokeswoman Kyle Shepherd told Haaretz. It is confident in the diagnosis of virgin birth because, she says, they sent the genetic material to the University of Tulsa for testing and the results are in: the progeny are solely hers – they are clones of the mother.

In fact the baby snakes result from a clutch of 61 eggs that Thelma laid in the summer of 2012, the zoo reports. The snake coiled on the eggs and brooded them for two weeks, until the zoo staff removed them for examination.

Far from the image of, well, cold-blooded parenting, pythons – the longest snake in the world - typically brood their eggs for about two months.

One of Thelma's babies, a genetic copy of the mother.Credit: Louisville Zoo

“It is not uncommon for a snake to lay infertile eggs, so the staff was surprised when the eggs appeared to be full and healthy instead of shrunken and discolored shells (typical of infertile reptile eggs),” says Bill McMahan, Curator of Ectotherms at the Louisville Zoo. The zoo then decided to artificially incubate some of the eggs – and the first child hatched a year ago. The six averaged a birth weight, bless them, of 148 grams.

Only recently has science begun to realize just how prevalent virgin births - parthenogenesis - are in nature, and Thelma is far from being the only reptile to have experienced it, though cloning hadn't been known in reticulated pythons before. More than 80 species of lizards, most famously whiptail lizards, don't even bother to have males.

Parthenogenesis is also known in several species of amphibians and fish – in 2008 a whole debate arose after the discovery of virgin birth in hammerheads. That led to speculation that parthenogenesis could save endangered species when the female can't even find a male to mate with. That in turn led to the counter-speculation that species propagating through cloning are doomed through lack of genetic diversification.

Virgin birth has also been widely recorded in arachnids, including scorpions (oh joy), insects – the list goes on. It does not include mammals. Any mammals. Not by nature at least.

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