How DNA Maps Could Save Animals
Efforts to create regional genetic databases of threatened animals could help wildlife experts protect them. In a study published this week, scientists at the University of Washington, in Seattle, developed a genetic-variability map of African elephants and then used it to find the origins of the largest illegal ivory seizure since the international ban on ivory began in 1989. The same technique could be used to help protect other animals subject to poaching, such as tigers and whales.
“Now we can identify which populations are being hit by poachers and can apply resources to protect the populations in greatest need,” says Bill Clark, coauthor of the paper and a senior advisor to the International Fund for Animal Welfare, an animal-advocacy organization headquartered in Yarmouth Port, MA.
After visiting Tanzania, the most heavily poached area of Africa, Sam Wasser, director of the Center for Conservation Biology at the University of Washington and lead author of the study, began the mapping project in 2002. (Wasser has pioneered the use of scat as a source of DNA.) To create the elephant map, he analyzed DNA samples from elephants in zoos and identified regions of their genomes that varied significantly among the animals. Wasser then convinced colleagues in Africa to send him elephant scat samples from around the country. Using 16 of these variability markers, the team created a map of the genetic diversity of African elephants–the first map of its kind.
Wasser also developed a technique to extract DNA from ivory, which he is now using to analyze poached elephant tusks seized in Africa. The researchers compare genetic markers from the tusks with the genetic-variability map and triangulate the source of the ivory. The results of their first study, published in the Proceedings of the National Academy of Sciences, showed that most of the tusks from a 6.5-ton ivory seizure in Singapore in 2002–the largest ivory seizure since the 1989 ban–came from elephants that had lived in Zambia.
“Until this technology became available, we could almost never trace elephant ivory back to the source,” says Clark. “We worked mostly with shipping and other documents, trying to track the seized ivory back to the port of export. But we could never trace it back to the population of animals.”
Wasser and his colleagues now aim to track the movement of illegal ivory all over the world. “Large-scale seizures in Africa, India, and China could now easily be tested and allow Interpol to track down and capture criminals in this trade,” says Peter Pueschel, manager of the wildlife trade program at the International Fund for Animal Welfare. The scientists are analyzing tusks from most of the major ivory seizures in the past 18 months.
Now that the DNA-variability technique has proved its worth, Wasser hopes that other scientists will spearhead similar projects for other endangered species. Several African nations have already expressed interest in developing maps for tigers, which are poached for their pelts, organs, and bones, as well as for various animals hunted for bush meat, some of which comes from endangered species such as gorillas. Wasser says the biggest challenge will be gathering a regionally diverse collection of scat samples to create the maps.
These types of maps could also aid in conservation efforts by allowing ecologists to design wildlife parks that take into account the movements of specific populations of elephants or other animals. Countries in southern Africa, for example, are considering creating a multinational “megapark” out of smaller wildlife parks throughout the region. Identifying genetically similar populations will allow scientists to place corridors between the different regions that keep animals from the same populations together. Says Rudi van Aarde, chair of the conservation-ecology research unit at the University of Pretoria, “It’s all about resurrecting traditional migratory patterns that have now been fragmented.”
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