Australasian Science: Australia's authority on science since 1938

Darwinian Relic Survives

By Stephen Luntz

DNA analysis reveals that a species with a significant place in scientific history may not be extinct after all.

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You have to respect anyone who weighs 400 kg and might have personally inspired Charles Darwin. Dr Ryan Garrick is on a quest to revive a species that was once considered extinct. He is studying the DNA of the Galapagos tortoises that inspired the concept of natural selection. Given the remarkable age to which the giants live, some of his subjects may have been around when the Beagle visited in 1835.

Tortoises are believed to have first arrived at the Galapagos Islands from South America. While poor swimmers, they can float for many months without food. Famously, the tortoises evolved two differently shaped shells, with protective rounded carapaces on wetter islands and a saddle shape for dry locations where longer necks are required to reach vegetation. Among these two dominant shapes, however, are many subtle variations.

In the 16th century an estimated quarter of a million tortoises inhabited the islands, but hunting reduced their numbers to just 3000 by the 1970s. Chelonoidis elephantopus, native to Floreana Island, was believed to have been wiped out entirely.

Disastrous as the arrival of humans on the islands proved, ships accelerated the movement of tortoises between islands. The tortoises’ capacity to survive long periods without food saw them treated like a canned meal to be eaten late in a voyage. However, when a ship was chased by pirates the...

The full text of this article can be purchased from Informit.