Female sharks can reproduce without having sex, scientists have found. A female hammerhead shark has given birth without mating with a male and its offspring has no paternal DNA.
An international team of researchers from Queen’s University Belfast, the Guy Harvey Research Institute at Nova Southeastern University in Florida and the Henry Doorly Zoo in Nebraska has found evidence that sharks can reproduce asexually by an unusual method known as “parthenogenesis”. This is the first scientific report of asexual reproduction in sharks.
Head of the Queen’s research team and study co-author, Dr Paulo Prodöhl, from the School of Biological Sciences, said: “The findings were really surprising because 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.”
“The discovery that sharks can reproduce asexually by parthenogenesis now changes this paradigm, leaving mammals as the only major vertebrate group where this form of reproduction has not been seen.”
The long-term study was prompted by the unexpected birth of a baby hammerhead shark in an aquarium at the Henry Doorly Zoo in December 2001. The astonishing thing about the birth was that none of the three candidate mother hammerheads in the tank, all of whom been caught in Florida waters as babies themselves, had been exposed to any male hammerhead sharks for the three years since their captivity.
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