A family tree for sharks

When biologist Nicholas Dulvy completes the world’s first family tree for sharks and rays in 2015, he will do more than shine a spotlight on 400 million years of evolution. The project will also reveal, for the first time, the birthplace of new shark species on Earth.

“We’ll be able to pinpoint the nursery areas for new shark species where evolution is proceeding quite rapidly,” says Dulvy, a Canada Research Chair in Marine Biodiversity and Conservation and a professor at Simon Fraser University (SFU). “We can literally map out the places on Earth where new shark species are being born.”

The implications of this work for prioritizing future shark conservation efforts could be profound. Not only is little known about the world’s sharks and rays, but more than 180 species are currently at an elevated risk of extinction, mostly from overfishing.

Similar in concept to a human family tree, the shark family tree is infinitely more complex. To reconstruct the evolutionary history of the world’s sharks, Dulvy must compare the DNA found in the cells of 1,000 different species. This DNA is literally the book of life, he says, and different genes, or chapters, in this book tell us about the evolutionary relationships of species. By comparing the genes, information can be gleaned about the differences and similarities in how species have developed and evolved over time.

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The project, which began in 2009, was originally supposed to take six months, but Dulvy admits he vastly underestimated the task. “There’s a good reason why this has never been done before,” jokes the Irish-born scientist, who is also co-chair of the International Union for Conservation of Nature’s Shark Specialist Group, a global authority on the conservation risks to sharks.

The task of analyzing enormous volumes of molecular data has been enabled by a “supercomputing cluster” at the Interdisciplinary Research in the Mathematical and Computational Sciences (IRMACS) Centre, located at SFU’s Burnaby campus and funded in part by the Canada Foundation for Innovation (CFI), which has contributed a total of $6.1 million to date. Established in 2004, the IRMACS Centre hosts numerous researchers across many disciplines, who collaborate and share the supercomputing infrastructure built into the site. Dulvy says the project would have been impossible without the computational power of the IRMACS Centre and the in-house technical expertise.

The shark tree was inspired by a similar project to create a family tree for the planet’s birds, completed last November by fellow SFU biologist Arne Mooers. Fascinated with the possibilities for a similar tree for sharks, Dulvy sought out Mooers in 2008 for guidance, and the two collaborated with former SFU biologist Jeffrey Joy, who mastered the complex task of connecting all the datasets together and feeding them into the IRMACS supercomputer.

The research will eventually identify shark species that are “evolutionarily novel” — living remnants of very distant lineages — and are thus a priority for conservation. “If we want to save evolutionary history,” says Dulvy, “if we want a museum of life, we can use this tree to identify the sharks that are the most evolutionarily distinct.”

By identifying both evolutionarily distinct sharks and evolutionary hot spots, Dulvy says the family tree can be a tool to direct shark conservation efforts where they are needed most. “We’re losing species 100 to 1,000 times faster than in the recent past and the fossil record. In this world of pinched funding, we need to be able to allocate that funding in a very smart way, and this tree helps us think about how we might do that.”

Targeting conservation efforts in more effective ways not only will protect the biodiversity of sharks for their own sake but, with apex predators like sharks at the top of the food chain, is instrumental in maintaining a balance of life in the ocean, which is essential for stable fisheries, tourism and recreation.

The tree will also make it possible to introduce the public to many new, wondrous shark species beyond the small group (think great whites and hammerheads) most of us currently know — such as swell sharks that expand like blowfish when threatened, cookiecutter sharks that drill and remove cores of flesh from the bodies of their prey and bizarre prehistoric throwbacks like the megamouth.

Once completed, the shark family tree will be unveiled to the scientific community through published journal articles and to the general public. A list of the most endangered and evolutionarily distinct shark species generated from the tree will become the focus for researchers recruited through Dulvy’s partnership with the Zoological Society of London. The society will also develop a website targeted to the public, similar to the one currently created for the bird family tree.

All this work will be an important step in understanding more about sharks, of which, says Dulvy, we know surprisingly very little right now. “We have discovered a new shark species, on average, every two weeks for the last 30 years. When I was growing up, I thought we had discovered everything on the face of the Earth, but it’s clear there’s much more out there.”