Shark has virgin birth
mongabay.com
May 23, 2007
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Writing in the journal Biology Letters, a team of scientists led by Dr Demian Chapman of the Pew institute for Ocean Science found no trace of DNA of male origin in the baby shark.
"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," said Dr Paulo Prodöhl of Queen's University Belfast in Northern Ireland. "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."
 Hammerhead sharks. Courtesy of USGS |
The researchers said the discovery raises concerns about the genetic and reproductive health of wild shark populations, which are fast dwindling in the wild due to overfishing.
"Not only does it experience reduced genetic diversity because it has no father, but around half of the genetic variation present in the mother is not passed on to the offspring," said Chapman. "Female sharks might reproduce like this more often when they have difficulty finding mates at low population densities. This could hasten the erosion of population genetic diversity and perpetuate the production of genetically disadvantaged offspring."
Earlier this year parthenogenesis was in the news when a female Komodo dragon reproduced asexually at Chester Zoo in northern England.
This article is based on a news release from Queen's University Belfast
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