Adapt and overcome. At least this is what scientists believe two species of shark have done to create a hybrid that can cope with climate change off the east coast of Australia. The Australian black-tip, whose range extends north from Brisbane, and the common black-tip from Australia's southeastern coastal waters have interbred, yielding a new shark able to tolerate both cooler and warmer waters. So far, 57 hybrid sharks have been found along a 1,243-mile stretch of coastline, from New South Wales and as far as north Queensland.
The astounding discovery, which, scientists add, has created a more 'robust' form of shark is unprecedented. While hybridization is common in plants and other fish because of egg release, sharks must physically mate. "It's very surprising," said lead researcher Jess Morgan from the University of Queensland, "because no one's ever seen shark hybrids before, this is not a common occurrence by any stretch of the imagination," Morgan told AFP
The interbreeding is believed to have occurred in response to rising sea temperatures caused by global warming. The new, potentially stronger hybrid is the world's first known hybrid shark which contains both common and Australian black tip DNA. By hybridizing, the new sharks are able to range further afield. The smaller Australian black-tip for example, is a tropical shark that needs warmer waters, yet the hybrid offspring has been discovered in much cooler waters.
Scientists are now wondering whether the hybrid offspring are limited to just these two species of shark. Fellow researcher Colin Simpfendorfer of James Cook University said, "we thought we understood how species of sharks have separated, but what this is telling us is that in reality we probably don't fully understand the mechanisms that keep species of shark separate."
Researchers also discovered that the hybrids accounted for 20% of black-tip populations in some areas, but did not displace the single-breed black-tips. Scientists describe the find as seeing "evolution is action."