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Virgin births have been reported in wild vertebrates

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BBC – To date this now includes around 10 species of snakes including a couple of boas, and a python, four species of shark, and several monitor lizards, including the endangered Komodo dragon.

Recently the zebra finch and Chinese painted quail were added to the list. All were kept in isolation in unnatural conditions and away from any males.

So to find asexual reproduction in two species of snake in the wild on their first attempt was “astounding”, according to Prof Booth and his collaborators.

Virgin births should no longer be viewed as “some rare curiosity outside the mainstream of evolution,” he said.

Evolutionary dead-end?

It remains unclear whether the female snakes actively select to reproduce this way, or whether the virgin births are triggered by some other factor, such as a virus or bacterial infection.

“Any answer is pure speculation at this point,” says Prof Booth.

In captivity, two sharks, and three snakes, have been shown to have had multiple virgin births, producing more than one litter via facultative parthenogenesis.

As yet, it also remains unclear whether the offspring of these wild virgin births can themselves go on to have normal, or virgin births of their own.

In captive snakes studied so far, offspring have so far not been proved viable, that is capable of surviving and reproducing.

However, earlier this year Prof Booth and colleagues reported that a checkered gartersnake that has had consecutive virgin births, appears to have produced viable male offspring.

Parthenogenicly born copperheads and cottonmouths are also currently being raised and “in the next two to three years we will know if they are indeed viable,” said Prof Booth.

“If they cannot survive and reproduce, then this is a reproductive dead-end.

“However, if they are healthy and can reproduce, that opens an entirely new avenue for research,” he said.

Being able to switch from sexual to asexual reproduction could be advantageous; in the absence of males a female could still give birth and start a new, albeit inbred, population.

Her genes could still be passed on via her fertile male offspring.

Scientists believe that facultative parthenogenesis is more common in some lineages such as reptiles and sharks.

However it is unlikely that similar virgin births will be found among placental mammals, which include all the mammals aside from the platypus and echidnas.

That is because mammals require a process called genomic imprinting to reproduce, where a set of genes from one parent dominates over the other. The interaction between the two sets of parental genes is required for embryos to develop normally.