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23/05/2007
NI scientists reveal shark fertilises own egg
Female sharks are able to produce without having sex, according to a team of international researchers from Queen’s University Belfast.
The discovery was made after a female hammerhead shark gave birth to a pup at Henry Doorly Zoo in Nebraska, despite having had no contact with a male.
The Guy Harvey Research Industry Institute at Nova Southeastern University in Florida and the Henry Doorly Zoo has found evidence that sharks can reproduce asexually by parthenogenesis.
This type of reproduction occurs when an egg cell is triggered to develop as an embryo without the addition of any genetic material from a male sperm cell.
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.”
Co-author Dr Mahmood Shivji, who led the Guy Harvey Research Institute Team, said: “We may have solved a general mystery about shark reproduction – our findings suggest that parthenogenesis is the likely explanation behind the anecdotal but increasing observations of other species of female sharks reproducing successfully in captivity despite not having contact with males.”
(JM/SP)
The discovery was made after a female hammerhead shark gave birth to a pup at Henry Doorly Zoo in Nebraska, despite having had no contact with a male.
The Guy Harvey Research Industry Institute at Nova Southeastern University in Florida and the Henry Doorly Zoo has found evidence that sharks can reproduce asexually by parthenogenesis.
This type of reproduction occurs when an egg cell is triggered to develop as an embryo without the addition of any genetic material from a male sperm cell.
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.”
Co-author Dr Mahmood Shivji, who led the Guy Harvey Research Institute Team, said: “We may have solved a general mystery about shark reproduction – our findings suggest that parthenogenesis is the likely explanation behind the anecdotal but increasing observations of other species of female sharks reproducing successfully in captivity despite not having contact with males.”
(JM/SP)
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