This huge insect has returned from extinction, but science can not explain why it is now different

in animals •  7 years ago 

On these lines you have the stick insect of Howe Island or tree lobster (Dryococelus australis). At the beginning of century XX, the rats that arrived with the settlers decimated this Australian species until the extinction. Now he has returned from the grave, but there is a problem: it is not exactly the same.

In 2001, scientists David Priddel and Nicholas Carlile visited Ball's Pyramid, an abrupt rocky islet 23 kilometers from Howe Island. What they found was a stick insect very similar to Dryococelus australis. This new stick insect was black rather than brown, and its legs were finer than those of its extinct relatives.

For decades, the insects found in Ball's Pyramid were supposed to be another species, but the similarities with their extinct relatives were excessive. A team of biologists has finally settled the issue after fully sequencing the DNA of both insects and comparing them. The task has not been easy. The only surviving specimens of this stick insect were dissected and exposed in museums, and that complicated the obtaining of valid DNA. To make matters worse, the complete genome to be analyzed and compared exceeded 4GB.

Finally, the work has paid off. The specimens found in 2001 are genetically of the same species. What the researchers fail to explain is why these stick insects from Howe Island are different. You probably are dealing with changes that have arisen for decades by living in a different environment than the original, but you do not know for sure.

Now the population of this species is being reintroduced on Howe Island. Biologists want to see if, with the passage of generations, the insects regain their original color and texture or change again. [Current Biology via Sciencemag]

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