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BRISBANE, Queensland -- University of Queensland research has found tiger sharks differ from many other sharks in that they donâ€™t use multiple paternity as a reproductive strategy.
UQ researcher Dr. Bonnie Holmes said multiple paternity occurred when a single litter of offspring was fertilized by multiple males, resulting in pups from the same brood having different fathers" which may ultimately increase the genetic diversity of a species.
Dr. Holmes said it was previously believed this was a wide-spread reproductive strategy among sharks, with half-siblings born at the same time.
â€œThe DNA of 112 tiger shark pups from Cairns, Rainbow Beach and the Gold Coast was tested to see if they had different fathers,â€ Dr. Holmes said.
â€œSurprisingly, all pups in each litter appeared to have the same father, except one.â€
Dr. Holmes said this provided critical information for managing the sustainability of tiger sharks globally.
â€œIt is the first genetic assessment of the reproductive strategy of these sharks,â€ she said.
â€œOn the Australian east coast, the species is targeted heavily in shark control operations, recreational game fishing activities and commercial fishing operations.
â€œTiger sharks in this region may have a reduced capacity to withstand significant fishing pressure, compounded by a reproductive strategy that may make them more vulnerable to loss of genetic diversity and reductions in effective population size.â€
Dr. Holmes said successful mating in sharks might depend on the rate of encounter between potential mates.
â€œBecause tiger sharks roam widely, multiple mating is probably less common as they are less likely to encounter a member of the same species.â€
She said further studies of tiger shark litters were required to corroborate the findings.
â€œAlthough multiple paternity is widely accepted as a common reproductive strategy in elasmobranchs (sharks, rays and skates), the frequency and prevalence may vary between species and populations.
â€œIf multiple paternity does occur in tiger sharks, it does so at extremely low frequencies within litters.â€
The research is published in Royal Society Open Science.
More information: Lack of multiple paternity in the oceanodromous tiger shark (Galeocerdo cuvier). Royal Society Open Science, rsos.royalsocietypublishing.or â€¦ /10.1098/rsos.171385