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Both feared and revered around the world, the great white shark is one of the most iconic creatures on the planet. Now, biologists have made a “major scientific step” and sequenced its entire genome, unlocking the secrets behind the species’ success.
Publishing their findings in the Proceedings of the National Academy of Sciences, the team discovered that the shark’s genome is an impressive 1.5 times the size of our own. They also found DNA sequence changes that imply various genes have adapted to enhance the stability of the shark’s genome. Basically, this means great whites have evolved to minimize damage to their DNA, something that can lead to diseases like cancer. (Despite the popular misconception, sharks can actually get cancer, but do so at a lower rate than humans.)
The team also spotted similarities between the great white shark’s genome and that of the larger, less toothy whale shark. This is interesting because both fish are incredibly big with long lifespans. Creatures with these features should, in theory, be more at risk of developing cancer as they have more cells and more time for things to go wrong. But both species swim against this current, cleverly evolving genetic strategies to reduce their risk. The fish also had genetic adaptations to allow for speedy wound healing, something sharks are incredibly good at.
"Decoding the white shark genome is providing science with a new set of keys to unlock lingering mysteries about these feared and misunderstood predators – why sharks have thrived for some 500 million years, longer than almost any vertebrate on Earth," explained Dr Salvador Jorgensen, a senior research scientist at Monterey Bay Aquarium, in a statement.
The great white genome was also found to contain a surprisingly high number of LINEs, a type of jumping gene (DNA sequences that can change their position within the genome).
"These LINEs are known to cause genome instability by creating double-stranded breaks in DNA," said co-leader Michael Stanhope. "It's plausible that this proliferation of LINEs in the white shark genome could represent a strong selective agent for the evolution of efficient DNA repair mechanisms, and is reflected in the positive selection and enrichment of so many genome stability genes."
We still have much to learn about the great white’s genome, but the researchers hope that understanding what makes it so stable could help humans in the fights against cancer and age-related diseases. It could also help conservationists working to save the species, which, as an apex predator, is hugely important for maintaining the delicate balance of marine ecosystems.
While great white sharks are feared across the globe, they have far more reason to fear us than we do them. Their numbers are waning thanks to intense fishing pressures, mainly from those trying to get hold of their coveted fins to use in shark fin soup.
"The genome data will be a great asset for understanding white shark population dynamics to better conserve this amazing species that has captured the imagination of so many," said conservation geneticist Steven O’Brien.
Changing attitudes is a huge challenge for conservationists attempting to raise awareness of sharks’ plight, so if you’re still not keen, check out these amazing pictures of divers swimming side by side with a powerful yet peaceful great white.
