Australian scientists say the discovery of interbred sharks off the east coast, the first hybrid sharks found, could signal the presence of ‘tropical’ sharks in waters as far south as Sydney. This may suggest the sharks are adapting to cope with climate change.
The mating of the 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 the lead researcher. But it's the scale of the discovery that has astonished the researchers. Multiple generations of the new creature have been identified in five locations between northern NSW and far north Queensland.
Offspring The university and government researchers say it is too early to tell why the hybrid sharks are themselves capable of reproducing -- unlike mules, for example -- or whether they'll supplant their parent species, but they say the discovery suggests other similar shark and ray species could also be interbreeding and improving their ability to adapt to climate change.
The new animal is a hybrid of the genetically distinct Australian black tip, whose range extends north from Brisbane, and the larger common black tip found in southeastern coastal waters. "Wild hybrids are usually hard to find, so detecting hybrids and their offspring is extraordinary," said Jennifer Ovenden from the Queensland Department of Primary Industries and Fisheries. "To find 57 hybrids along 2000km of coastline is unprecedented."
Stronger sharks? University of Queensland research scientist Jess Morgan said hybridisation was common in plants and relatively common among fish because of their external fertilisation. "They just release their eggs and sperm into the water column," she said. "(But) sharks physically mate, which is usually a good way to make sure you don't hybridise with the wrong species." It is possible that hybridisation makes the sharks stronger, which could change the behaviour of the otherwise quite passive black-tip reef sharks.
The discovery highlights how little is known about commonly observed sharks. Scientists are unsure how or even when the hybridisation had taken place.
Sources: The Australian and Yahoo Photo: Supplied by the University of Queensland