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Monday Reads: The Hybridizing Shark Edition

Climate change has been accused of being many things, from Imposter to Glacier National Park Name-killer. And now to the list we can add...Interspecies Dating Matchmaker?

A study published last month in Conservation Genetics documented no fewer than 57 instances of hybrid common black-tip (Carcharhinus limbatus) and Australian black-tip (Carcharhinus tilstoni) sharks off the eastern coast of Australia. The number of hybrid sharks previously uncovered in the wild or at your friendly neighborhood aquarium? Zero.

The concept of hybridization between distinct species is not a new one. (Who can forget the wholphin? The pizzly bear?) But what makes this case interesting is the sudden abundance of hybrids in species who, until this time, have (as far as we know) diligently remained within their predefined mating circles.

The common black-tip prefers chillier waters and is found all over the world, while its local counterpart confines itself to the balmy tropics. This development has opened up a whole new world for the little-traveled Australian black-tip, as its hybrids enjoy a much greater range.

So is climate change becoming the OkCupid for the wild? The jury’s still out on what brought the adventurous couples together (the hybrids expanded into an area of more temperate, not warmer, waters), but scientists do offer that the new hybrid may have a dorsal fin up on either of its purebred parents. According to study lead researcher Jessica Morgan of University of Queensland, “Hybrids have a wider temperature tolerance than their parents, which may make them better adapted to coping with future temperature fluctuations caused by climate change.”

Little pika ponders big climate change questions. (Sally King / NPS)

A rapidly changing habitat due to climate change is a grim reality facing many species today. The American pika can overheat at a mere 78°F. Half a world away, Europe’s edelweiss (of Rodgers and Hammerstein fame), are in the same sweaty boat. The mountains are getting warmer, but they aren’t getting any taller. Alpine species specifically adapted to the cold are moving up the mountains in search of colder climes and will soon reach a literal and figurative dead end. The recently concluded UN climate talks in South Africa did little to reassure the world that our future is on a course for the better. (Read Earthjustice Attorney Erika Rosenthal’s analysis from Durban.)

But back to the sharks. In a time when sharks are facing an uncertain future due to decades of overfishing (in recent years, Earthjustice has gone to court on their behalf), this recent scientific discovery may help put the spotlight of public interest on the imperiled species. And on a more lighthearted note, in all the many news articles, not one of them mentioned what many of us were undoubtedly wondering: in the grand tradition of zedonks, jaglions and beefalos, what fantastic name will these newfound hybrids be given?

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