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Hybrid Sharks Discovery: Is There a Global Warming Connection?

In the movie "Austin Powers," the villain, Dr. Evil, demands that his henchmen find sharks with lasers on their heads in order to intimidate and kill his enemies.

Based on a news story out of Australia today, I suspect that if the same movie were to be made now, Mike Myers' Dr. Evil character would demand "hybrid sharks" with lasers on their heads instead. 

According to a wire report published by Discovery News, scientists working off the coast of Australia have discovered the world's first hybrid shark species, a mix of the local Australian blacktip shark with the global variety, the common blacktip.

The common blacktip shark. Credit: Wikimedia Commons.

The researchers found that the hybrid sharks are breeding, with several generations of offspring found among the sharks they performed genetic testing on. "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," said Jess Morgan of the University of Queensland. "This is evolution in action."

The story suggests that there may be a climate change connection, since the Australian blacktip shark has a more limited range compared to its more common cousin. As the story states:

"The Australian blacktip is slightly smaller than its common cousin and can only live in tropical waters, but its hybrid offspring have been found 2,000 kilometers (1,243 miles) down the coast, in cooler seas."

"If it hybridizes with the common species it can effectively shift its range further south into cooler waters, so the effect of this hybridizing is a range expansion," Morgan said. "It's enabled a species restricted to the tropics to move into temperate waters."

The story speculates that the hybridizing may be due to global warming-related changes in sea surface temperatures. However, that seems like a stretch, considering how little is known about sharks in general, as well as how they may respond to climate change. It's quite possible that the hybrid black tip sharks have existed for decades, and researchers only stumbled across them now.

It's also possible that hybridizing is an aspect of shark evolution that has simply evaded researchers, and that some hybrid species will have advantages over others as the climate changes. In other words,it may just be luck that a hybrid shark species like this one will fare better in a changing climate.

Comments

By Heather Goldstone (Woods Hole, MA)
on January 3rd, 2012

I’m missing something. The ability to tolerate cooler waters doesn’t seem like a great climate change adaptation. Quite the opposite.

Reply to this comment

By Andrew
on January 3rd, 2012

Hi Heather,

I thought the same thing myself when I read the AFP dispatch on this discovery. But I think the point is that by having an expanded range, a species can more easily adapt to climate change, versus one that is limited to a smaller area. Not all areas of the ocean are warming, and not all depths are warming, so sharks that call temperate waters home may be better off than tropical sharks that may have less tolerance to warmer temps.

Reply to this comment

By Daryl McCann (West Palm Beach, FL 33407)
on January 8th, 2012

Please got to:
http://www.change.org/petitions/the-president-of-the-united-states-pledge-to-reduce-man-made-co2-in-the-united-states-by-50-in-5-years
and sign the petition today and send it on to all in your contact list.

It is the duty of every human being to do what he or she can to stop this tragedy. We will not effectively do this until our nation’s governments do the following. Each official or those running for office must:
1. Publicly declare that they recognize global warming as a real phenomenon.
2. Publicly declare that man-made activities are increasing global warming.
3. Pledge to reduce our CO2 emissions by 50% within the next five years. (Effectively, their next term in office.)
5. Pledge not to alter their stance and policy on this matter.
6. Pledge to stimulate effective, non-greenhouse gas emitting energy alternatives and technologies.
7. Pledge to remove all subsidies and tax breaks for dirty energy such as coal, oil and natural gas, except when those subsidies are utilized to reduce their greenhouse gas emissions by 50% or more.
8. Pledge to apply tariffs on products produced in countries that do not take the same course of action and reduce their greenhouse gas emissions by 50%.

Thank you for your help.

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