“In April 2016 Leonie hatched three eggs, despite having no access to a mating partner for three mating seasons. Shark embryos have developed without fertilization. In the absence of a mating partner for more than 3 years, Leoni the Zebra Shark hatched three eggs by herself. Zebra shark, named Leoni, has switched her reproduction from sexual to asexual. “We still need to keep them within arm’s reach.Zebra shark at Townsville’s Reef HQ Aquarium has made a historic change that could save her species. So, offspring produced asexually have not yet been seen to create their own offspring sexually.īut the million dollar question for all concerned males: are the guys really obsolete? “Maybe in the short term the female (sharks) can do without males, but in the long term we need males again eventually,” Dudgeon said. Nobody has previously demonstrated successful sexual reproduction for offspring produced through facultative parthenogenesis.” Unfortunately they’ll be more prone to problems due to the reduction in the diversity of their genetic makeup, but if they survive to that point, I know myself and other researchers are interested in finding out more. “We are keeping an eye on them, and ultimately we want to find out if her offspring can reproduce sexually,” she said, as such an occurrence would be unusual. “It’s a real concern.”ĭudgeon and her team are now waiting for Leonie’s offspring to reach sexual maturity before taking the next step in their research. “The news that they are endangered was horrific news for biologists all over the world,” he added. “These sharks are an apex predator, so they are like the proverbial canary down the mineshaft – they are a poignant indicator of the quality of the environment in general,” said Tristam, who is grateful that Leonie’s case is attracting increased attention to the plight of the species. Zebra sharks, also known as leopard sharks, were once a widespread species resident in tropical waters around the globe, but have recently been highlighted as an endangered species by the IUCN Red List of Threatened Species. “Long term, they need to diversify to help them adapt to their environment.” ![]() “ the genetic diversity of animals gets greatly reduced using this reproductive method,” said Dudgeon. “One theory is that in the wild, if for some reason males can’t have contact with the females for one breeding season, they can keep their lineage going for one or two seasons, until they can reproduce the traditional way,” said Tristam. ![]() There are several theories surrounding Leonie’s sudden unusual behavior. “She had been mating successfully for several years, and there was nothing much published about such large animals switching reproductive strategy so quickly.” “It was definitely a surprise,” said Hamish Tristram, a senior aquarist with Reef HQ. Genetic analysis of Leonie’s hatchlings displayed elevated homozygosity, meaning more genes are identical, and less diversity pointing to the likelihood that they had been produced asexually, rather than sexually through sperm storage. This has been seen in a handful of sharks, but none that had mated previously.” Sharks have been known to store sperm from male sharks for extended periods of time.” “One was sperm storage, which has been documented in several occasions. ![]() “There were two possible explanations for Leonie’s eggs hatching,” said Dudgeon.
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