Mystery of virgin shark birth solved
Wednesday, 23 May 2007 11:55
A hammerhead shark reproduced in 2001 without a male
Science In Focus
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How a female shark managed to give birth to a pup without being in contact with a male for three years has been solved by scientists.
In December 2001 one of three captive female hammerhead sharks gave birth to a normally-developed, live female pup.
This birth puzzled scientists as the sharks had been in captivity for too long to be become pregnant by sperm storage.
US and British researchers therefore began to investigate the theory that the birth was the result of a-sexual reproduction, where one animal is able to reproduce without the need for the opposite sex.
They compared the DNA of the shark pup and its mother and found that the pup possessed no DNA from a male.
Writing in the Royal Society journal Biological Letters, the scientists argue that the pup was "unambiguously" from the mother alone.
They therefore claim that now a-sexual reproduction has been confirmed in a shark, the process has now been demonstrated "in all major jawed vertebrate lineages except mammals".
"Our results suggest that accumulating cases of female sharks producing healthy offspring in the absence of males warrant genetic evaluation to determine how common asexual reproduction… is among these ancient fishes," they conclude.