[Animals] Female zebra shark opts for 'virgin birth' even when sharing a tank with healthy males

[-Sethu]

A female zebra shark (Stegostoma fasciatum) has given birth by fertilizing her own eggs, despite sharing a tank with two healthy males who likely would have been eager to help, reports a new study in the Journal of Fish Biology(opens in new tab). This unusual scenario challenges prior assumptions about the risks and benefits of parthenogenesis — a form of asexual reproduction sometimes nicknamed "virgin birth" — according to the study's authors.

"This is only the second case that we know of where sharks have been born by parthenogenesis even when there were healthy mates available," study author Kevin Feldheim(opens in new tab) of the Field Museum of Natural History in Chicago, said in a statement(opens in new tab). "This latest paper is just another step in learning why these 'virgin births' happen."

A number of bird, reptile, amphibian and fish species use parthenogenesis as a biological back-up plan for reproducing when mates are hard to come by. But the process can be risky; animals born via parthenogenesis generally have shorter lifespans and are often sterile, which may explain why vertebrate species capable of asexual reproduction seldom choose to utilize it unless they're out of options. 

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