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Australia’s Evolving Hybrid Shark

Posted: January 4th, 2012 | Author: | Filed under: Applied Science, Cankler Science News, Ecology | Tags: , , , , , , , | Comments Off on Australia’s Evolving Hybrid Shark

Marine biologists have for the first time observed a potential new mechanism of evolution. While cataloging sharks it was discovered that Australian Black Tipped sharks are adapting to the changing environment off the Australian East Coast through interbreeding with it’s cousin, the common Black Tipped shark. It is believed that if the changes are successful this will produce a stronger species, unlike all of Hollywood’s versions of man building a super shark nature is in charge here, and unfortunately she hasn’t integrated lasers just yet.

DNA tests have shown the hybridized version to be a mix of the Australian Black Tipped shark and the common Black Tipped shark found in other parts of the world, two distinct species of shark. While the Australian Black Tip is a tropical water shark the hybrid version has adopted its overseas cousins ability to travel into cooler waters. This will allow the new Black Tip to travel further south expanding its hunting territories and increasing the sharks chances of survival. This is evolution in action.

Australias Evolving Hybrid Shark

“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,” lead researcher Jess Morgan, from the University of Queensland

These new findings are challenging our understanding of the mechanisms that maintain the boundary between sub-species, with the separation between sub-species of sharks being blurred in this case. DNA testing has proven to be invaluable as the hybrid shark still has the physical properties of the Australian Black Tip, while it’s DNA showed hybridization, potentially creating a new sub-species.

Sharks unlike fish and many other marine animals bread through mating pairs, sharks actually choose a mate and they’re usually pretty discerning who they breed with, never breeding with other sub-species – cousins -. Biologists have theorized that hybridization is a possibility within the shark population but it has never actually been observed before, until now. Frankly it’s not surprising, who wants to try to collect DNA from sharks after all.

To eliminate the chance that this was a once off change scientists sampled a wide population of sharks in the population off the central New South Wales coast. Initial studies suggested the hybrid species was relatively robust, with a number of generations discovered across 57 specimens tested.. It was found that 20% of sharks in that population were carrying the new hybrid DNA.

“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,” said Colin Simpfendorfer, a partner in Morgan’s research from James Cook University

Scientists are now trying to discover the drivers in this change, with theories ranging from changing water temperatures, over fishing and other environmental factors. The advancement of DNA testing and it’s use in new fields is revolutionizing the way we look at the natural world. With these new tools we are discovering natures secrets and in the process improving the understanding of this world full of wonders.

Source: AFP


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