By METRO.CO.UK
Added: Tue, 22 May 2007 23:00:00 UTC

Thanks to Billy Sands for the link.

Reposted from:
http://www.metro.co.uk/news/article.html?in_article_id=50123&in_page_id=34

It was the 'virgin birth' that baffled scientists for years.

But now the mystery of a hammerhead shark born at a zoo where there were no male sharks has been solved — it seems females of the species can reproduce without having sex.

The shark was born at the Henry Doorly Zoo in Nebraska in 2001 and there were three potential mothers in the same tank.

All had been in captivity for at least three years. Scientists thought one of them might have mated before being captured and stored the sperm for fertilisation.

But when they analysed the baby shark's DNA, it matched up only with its mother's.

Dr Paulo Prodohl, of the School of Biological Sciences at Queen's University in Belfast, said: 'The findings were really surprising. As far as anyone knew, all sharks reproduced only sexually by a male and female mating — requiring the embryo to get DNA from both parents for full development, just like in mammals.'

Females of a small number of vertebrate species can give birth to fully formed young without requiring eggs to be first fertilised by a male's sperm.

This ability, known as parthenogenesis, is seen in some birds, reptiles and amphibians.

However, it has never been seen before in sharks.

Research co-author Dr Mahmood Shivji said: 'It now appears that at least some female sharks can switch from a sexual to a non-sexual mode of Discovery: Researchers found a female hammerhead shark conceived asexually reproduction in the absence of males.'

TAGGED: BIOLOGY