Further tests, however, revealed that the pups’ lack of genetic diversity meant they were most likely the spawn of one parent, not two. And so when the zebra shark gave birth, scientists at the Queensland aquarium also wondered if stored sperm was to blame. In the snake’s case, her offspring couldn’t have been fertilized by sperm, because she had never been near a male. ( Read “World's Longest Snake Has Virgin Birth-First Recorded in Species.”) When a reticulated python had a “virgin birth” at the the Louisville Zoo in Kentucky, scientists were so surprised that they at first wondered if this was a case of stored sperm.
Yet after three years of separation from a male, scientists were stunned to see some of her eggs hatch.Īlthough this switch from sexual reproduction to parthenogenesis-reproduction without fertilization-is a first for sharks, it has also been observed in a spotted eagle ray and a Colombian rainbow boa.Īsexual reproduction without prior sexual reproduction has also been observed in plenty of creatures that don’t normally do it that way. In her new tank, Leonie continued to lay eggs whether they were fertilized or not, just like chickens do. In 2012, she was moved into a separate tank at the aquarium with no male sharks. Leonie had previously given birth after mating with a male shark at the Reef HQ aquarium in Townsville, Queensland. ( Read “‘Virgin Birth’ Record Broken by Hotel Shark.”) This isn’t the first time that a zebra or leopard shark ( Stegostoma fasciatum) has had a “virgin birth,” but it is the first time that scientists have seen this behavior in a shark that wasn’t, ahem, a virgin. ( Read our earlier story about the birth.) Parthenogenesis occurs when one of the polar bodies has the same amount of genetic material as the egg and fertilizes it.Scientists in Australia published a paper on Tuesday about a female shark that performed a “virgin birth.” Although she hadn’t been around a male shark in three years, the captive zebra shark-named Leonie-laid eggs that hatched three viable pups.
Usually these polar bodies are simply reabsorbed by the female. During egg development, one egg is produced along with three other products called polar bodies. In sharks, asexual reproduction usually happens via a process called "automictic parthenogenesis," explained Feldheim. This was the first time a vertebrate (animals with backbones inside their body), which usually reproduces the conventional way with a mate, was found to reproduce asexually in the wild, Feldheim said. One study from the Field Museum discovered parthenogenesis in a wild population of smalltooth sawfish, a type of ray. "We don't know how common it is and the handful of cases we have seen have mostly taken place in an aquarium setting," Feldheim told DW. It isn't the first time parthenogenesis has been seen in sharks , and the process has been observed in a number of other shark species.īut scientists still don't know how often it happens, says Kevin Feldheim, a researcher at the Field Museum in Chicago, who researches the mating habits of sharks. To view this video please enable JavaScript, and consider upgrading to a web browser that supports HTML5 video Why do whales swim differently from sharks?
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