By Laura Spadanuta
Although the international ivory trade was banned in 1989, the levels of illegal elephant killings continue to rise, estimated to be in the tens of thousands in 2011 alone, according to statistics from Monitoring the Illegal Killing of Elephants. Some estimates go even higher. As the ivory trade thrives, researchers are testing new ways to pinpoint where the illegal ivory is coming from in an attempt to aid antipoaching efforts.
Nicholas Georgiadis, of the Puget Sound Institute, says researchers originally hoped that if elephants had DNA structures similar to some other animals, such as giraffes, then it would be easy to decipher where ivory had come from. But that didn’t prove to be the case.
Between the African savanna and rainforests, two elephant species developed over millions of years. But the genetic markers within each of those species are very similar. Thus, it is difficult to detect where ivory came from by analyzing DNA. “It’s not straightforward, so you need much more information to know where a tusk is from,” Georgiadis says.
Researchers led by University of Illinois Assistant Professor Alfred Roca have looked at mitochondrial DNA (mDNA), taken from within a cell, rather than just nuclear DNA which was more traditionally studied. The mitochondria are the part of the cell that generates most of the cell’s chemical energy. Looking at mDNA is a breakthrough because it is only passed down by females, and unlike male elephants, females do not migrate outside of the herd. So while other genetic markers are spread across the landscape, “the mitochondrial DNA and any mutations in the mitochondrial DNA end up being bound to the herd,” says Roca.
According to the sequencing done by Roca’s lab researcher Yasuko Ishida, 72 percent of the mDNA was unique to one locality and 84 percent of it was actually country-specific.
The mDNA provides a tool to combine with the nuclear DNA analysis to better confirm where the ivory is from. Sample mDNA can be taken from seized illegal ivory and compared with the samples taken by biopsy darts shot at elephants (the darts feel like an insect bite).
Roca says he was concerned that the DNA obtained from the ivory would not be as good as the DNA in the tissue samples obtained directly from the elephants. However, Roca says, the researchers found the short sequences of the seized ivory to be adequate for comparison. “We still found a hundred and one unique sequences different from each other and 62 percent of them were present only in a single country,” Roca says.
Georgiadis says that this approach is not easy for researchers to use just yet as it takes strenuous analysis, but he hopes that with time, it will become a more typical application.
Meanwhile, there is other DNA work being done that is more routine. One example, says Georgiadis, is what’s being done by Samuel Wasser, who is the director of the Center for Conservation Biology at the University of Washington. Wasser and the center have worked with the Interpol Wildlife Crime Working Group and the Lusaka Agreement Task Force (LATF) to compare DNA from tusks to elephant dung. This work helped investigators find general areas where poaching was taking place. It also revealed that the ivory was not being shipped directly from where it was poached.
But these findings did not go far enough in identifying precise poaching locations. If the mDNA research can narrow ivory origin even further, the researchers hope that countries can use that information to strengthen law enforcement or surveillance in those areas and possibly prevent the continued slaughter of elephants for their ivory.