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The researchers noted that sawfish could be the first entire family of marine animals to be driven to extinction, which is occurring due to overfishing and loss of the animals' coastal habitats. Smalltooth sawfish have already disappeared from most of the places in the Atlantic where they were common a century ago.
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Between and , the researchers sampled DNA from smalltooth sawfish. All of the fish were tagged and released back into the wild as part of an ongoing study of sawfish movements. The scientists found seven parthenogens, representing about 3 percent of the sawfish the researchers investigated.
Five of these seven appear to all be siblings of about the same age, probably members of a single brood. Sawfish and many other creatures carry out meiosis, in which cells divide to form sex cells, each of which only possesses half the material needed to make offspring. In the female sawfish the researchers investigated, pairs of sex cells likely fused to generate offspring.
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However, these progeny are not clones of the mother or each other; sex cells are not perfectly identical to each other, and neither are the parthenogens resulting from these sex cells. Since virgin birth is essentially an extreme form of inbreeding, "there was a general feeling that vertebrate parthenogenesis was a curiosity that didn't usually lead to viable offspring," study co-author Gregg Poulakis of the Florida Fish and Wildlife Conservation Commission, who led field collections of the sawfish, said in a statement.
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