Although outlawed for almost 15 years, illegal trade in African elephant ivory is booming. But conservationists may now have a new weapon in their fight against poachers. Genetic testing of tusks can reveal their exact provenance.
African elephants have been having a rough time of late. Extensive hunting in the 1980s brought down their numbers from 1.3 million to less than 500,000 alive today. And although in 1989 the worldwide trade in their ivory was called to a halt by the Convention on International Trade in Endangered Species (CITES), poached ivory has been turning up in ever larger quantities on markets around the world, such as Hong Kong, where almost 2 tons were seized last October. Exactly where and how African elephants are hunted is not clear, especially when it concerns the rare and elusive forest elephant, says conservation biologist Samuel Wasser of the University of Washington, Seattle.
Together with two colleagues from the Fred Hutchinson Cancer Research Center in Seattle, Wasser developed a technique, published in the December issue of Conservation Biology, for genetic fingerprinting of poached ivory. Tusks are teeth and thus made of material called dentine. The dentine is secreted by cells in the jaws and some DNA from these cells might be locked inside the ivory, Wasser reasoned. Using a 16-millimeter drill bit, the researchers took cores from tusks and subjected amounts the size of a kernel of corn to a sensitive DNA extraction method.
Sure enough, the ivory contained considerable amounts of intact DNA. What's more, when the team used this DNA in a yet unpublished genetic fingerprinting procedure, currently being developed by them for the African elephant, they obtained profiles as good as those from tissue or blood samples. Researchers have already established that elephant populations have characteristic DNA profiles, and they've sampled more than a hundred known populations. So it is now possible to tell exactly where a confiscated lot of illegal ivory was poached, sometimes down to the exact forest area. This may help wildlife officers focus enforcement on trouble spots.
The work is an "exciting demonstration of the use of molecular genetic tools," says elephant geneticist Lori Eggert of the Smithsonian Institution in Washington, D.C. The new technique is an important step forward in the monitoring and enforcement of trade restrictions, she says.