The first hybrid shark ever discovered: the mating of the two species – local Australian black-tip shark with its global counterpart, the common black-tip – was an unprecedented discovery with implications for the entire shark world.


Hybrid sharks ‘evolution in action’

Last updated 09:38 04/01/2012
Black-tip shark

Wikimedia Commons
A common black-tip shark.

The world’s first hybrid sharks have been discovered off the Australian coast, scientists say.

Researchers found 57 of the new sharks along 1200 miles of coastline between New South Wales and Queensland, with the interbreeding possibly a response to climate change or fishing patterns.

The mating of the two species – local Australian black-tip shark with its global counterpart, the common black-tip – was an unprecedented discovery with implications for the entire shark world, said lead researcher Jess Morgan.

“It’s very surprising because no one’s ever seen shark hybrids before, this is not a common occurrence by any stretch of the imagination,” Morgan, from the University of Queensland, told AFP.

“This is evolution in action.”

Like its two parent species, the new shark is not considered dangerous – and scientists say there is no risk of the hybrids leading to a Jaws-style “mega-shark”.

The hybrids were found at five locations and identified using genetic testing and body measurements.

While the two parent black-tip species are closely related, they grow to different maximum sizes and are genetically distinct.

Colin Simfendorfer, a research partner from James Cook University, finding the hybrids was “very unusual”.

“Telling the hybrids is extremely difficult, which is why it has never been done before,” he told ABC Radio.

“It came very much out of leftfield. We didn’t think it was a possibility, but lo and behold there it was.”

Simfendorfer said hybrids were often sterile but there was evidence the new sharks have been breeding both with each other and with members of the separate black-tip species.

Surprisingly, he said, the hybrids are not the average size of the two interbred species but tend to be roughly the same length as one species or the other.

A Queensland marine scientist, Dr Jennifer Ovenden, told the Telegraph the sharks may be adapting to changes in the environment and other closely related sharks and rays may also be interbreeding.

“Wild hybrids are usually hard to find, so detecting hybrids and their offspring is extraordinary,” she said.

“Hybridisation could enable the sharks to adapt to environmental change as the smaller Australian black tip currently favours tropical waters in the north. The larger common black tip is more abundant in sub-tropical and temperate waters along the south-eastern Australian coastline.”

Asked whether there was any risk of a “mega-shark” developing, Simfendorfer said: “We don’t think there’s any issue with that at all. Both of these species we don’t consider a danger to humans. Given that they keep the same sort of morphology of one or other of the parents, we should see no visible change in terms of what we see out there in the ocean.”

– © Fairfax NZ News


The Times of India

Climate change: Hybrid sharks mark survival strategy

PTI | Jan 4, 2012, 06.48AM IST

MELBOURNE: Researchers have discovered the world’s first hybrid sharks in Australian waters, indicating that animals are adapting to climate change for survival.Leading researchers in marine biology have come across 57 animals along a 2,000-km stretch from Queensland to New South Waleswhich they believe are the result of cross-breeding between the common black-tip shark and Australian black-tip shark, two related but genetically distinct species.The inter-breeding between the two species shows that the animalsare adapting to climate change and the hybridization can make the fishes stronger, the scientists said.”Hybridization can enable sharks to adapt to ecological change as the smaller Australian black-tip currently favours tropical waters in the north while the larger common black-tip is more abundant in sub-tropical and temperate waters along the south-eastern Australian coastline ,” Jennifer Ovenden of Queensland department of primary industries and fisheries said.

“Wild hybrids are usually hard to find, so detecting them and their offspring is extraordinary. To find 57 hybrids along 2000-km of coastline is unprecedented ,” she said.

Another researcher at the University of Queensland researcher, Jess Morgan, said it was unusual for sharks to breed in such a way. She said as sharks physically mate, it makes sure they do not hybridize with the wrong species.

The find was made during cataloguing work off Australia’s east coast when genetic testing showed certain sharks to be one species when physically they looked to be another. Colin Simpfendorfer of James Cook University’s Fishing and Fisheries Research Centre, said the results of this research show that we still have a lot to learn about these important ocean predators.


Voice of America

Aussie Sharks ‘Evolving’

Posted Wednesday, January 4th, 2012 at 11:00 am

Some feared predators off the Australian coast appear to be adapting.

A team of Australian scientists says it has identified 57 sharks that appear to be the result of mating between two species, making them the first-ever hybrid sharks identified in the wild.

The scientists say the hybrid sharks are a combination of the common blacktip shark and the smaller Australian blacktip shark, which lives in warmer tropical waters near the coastline.

The researchers say the new, hybrid sharks live along a 200 kilometer stretch of Australia’s northeastern coast but have ventured more than 1,600 kilometers south, to cooler waters.

The scientists say they do not know for certain why the two species started interbreeding but suggest it may be an evolutionary process to adapt to climate change or pressures on their food supply.

The findings appear in the journal Conservation Genetics.


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