Air Date: Week of January 27, 2012

This hybrid shark has both Australian blacktip and common blacktip DNA. (Pascal Geraghty (NSW DPI))

Scientists have discovered the first known examples of hybrid sharks, the result of interbreeding between Australian blacktip and common blacktip sharks. As Living on Earth’s Mary Bates reports, the hybrids appear to be thriving in Australian waters and span multiple generations.

Transcript

GELLERMAN: Just ahead – the development of a contagious virus in the lab threatens the spread of scientific information. But first this Note on Emerging Science from Mary Bates.

[SCIENCE NOTE THEME]

BATES: Two shark species are doing something totally new to science – interbreeding and producing hybrid offspring. For the first time ever, scientists have discovered widespread hybridization in the wild between two shark species. In a census of Australian marine life, a team led by scientists from the University of Queensland and James Cook University found 57 hybrid sharks, spanning multiple generations.

The hybrids are a mix between the Australian blacktip shark and the common blacktip shark. Genetic analyses revealed that the hybrids are mating with both other hybrids and purebred members of the original species. The scientists say wild hybrids are usually hard to find. They discovered the sharks’ true identities using genetic testing and body measurements. Australian blacktips and common blacktips look very similar, but they grow to different maximum sizes and are genetically distinct.

And while this is the first time scientists have seen interbreeding between two shark species, that doesn’t mean it’s not happening elsewhere in the ocean. Other closely related shark species around the world may be mating and producing hybrid offspring. Scientists just haven’t caught them in the act yet.

Meanwhile, back in Australia, scientists are planning to investigate where Australian blacktips and common blacktips meet and mate. They also want to measure the fitness of the hybrids and figure out how they might differ from their parent species. Scientists are hoping the private lives of these sharks won’t remain private much longer. That’s this week’s Note on Emerging Science, I’m Mary Bates.

 

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Article in Conservation Genetics