Researchers on Tuesday confirmed the second known case in which a baby shark appears to have been conceived without the mother having mated with a male.
According to a weekend report in The Journal of Fish Biology, the study seems to indicate that female sharks can reproduce without fertilization of their eggs by a male.
Dermian Chapman, a shark expert at the Institute for Ocean Conservation Science at the State University of New York at Stony Brook, a lead author on the study, said DNA tests performed on the infant shark confirmed that there had been no father.
The baby is the progeny of "Tidit" a female blacktip shark that has lived for eight years in an aquarium in Virginia and never had contact with a male.
Scientists said the birth is the second confirmed instance of a shark being conceived by parthenogensis -- a process in which an unfertilized egg develops into a new individual.
The process was generally believed, until now, to occur only among certain insects, spiders, centipedes, and crustaceans.
The first case of parthenogenesis in sharks was documented in May 2007, when a female hammerhead which had had no contact with male in the previous three years, gave birth at an aquarium in Omaha, Nebraska.
The study found nearly a dozen instances in recent years of suspected "virgin births" in sharks, but said scientists had attributed the surprise offspring to longterm sperm storage by the females after mating with male sharks.
They now say that asexual reproduction now is the most likely explanation.
© 2008 AFP
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