Tracing poached ivory to the source
Online tool matches genetic sequences to a database.
By Natalie Parletta
A new software tool will speed up the tracking of locations where African elephant tusks have been poached for ivory.
The freely available interactive tool, Loxodonta Localiser, draws from a comprehensive database of elephant DNA and geographical locations put together by researchers at the University of Illinois, US.
Senior researcher Alfred Roca has been working on elephant genetics for 22 years and saw an opportunity to develop a straightforward method to quickly deduce the source of confiscated ivory and help stop poaching.
This is an increasingly serious issue; the weight of illegally poached ivory tripled from 2007 to 2016, according to estimates by the Convention on International Trade in Endangered Species (CITES).
Because of this, more African elephants die from poaching than from natural causes: forest elephant (Loxodonta cyclotis) populations have dwindled by more than 60% and savanna elephants (L. africana) by a third.
Current methods to infer the source populations of confiscated tusks use nuclear genetic markers. This can help identify individual elephants, but establishing their geographic origin is a complex task requiring more genetic data and statistical modelling, according to Roca.
His team drew on mitochondrial DNA which can give insights to their location, because it is only passed from mums to their offspring and the females don’t disperse.
“The females kick the males out of the herd at puberty and the males have to go out on their own,” Roca explains. “Females stay with the herd and that herd tends to stay in certain localities.”
Sourcing published scientific studies, Roca’s student, Kai Zhao, combined all of the relevant mitochondrial sequences for African elephants, verified by his technician Cory Green.
“The region of overlap across the major studies was 316 base pairs of DNA, and this information is what is stored in the database,” says Roca. It currently includes sequences for more than 1900 elephants from 24 countries.
To use the database, forensic laboratories can generate sequences from ivory and enter them as a query on the home page of the software. This will generate a map and details of where the sequence has been reported previously in African elephants.
The researchers tested it with three confiscated batches of ivory, two from Malaysia and one from Hong Kong. Their results suggested the elephants were being killed in the Tridom region of west-central Africa.
“This is the largest surviving population of the African forest elephant,” says Roca, “which is a distinct and more highly endangered species from the African savanna elephant, and it is being targeted by poachers.”
Importantly, the Malaysian co-authors were able to extract DNA from the ivory, amplify and sequence it and source its location within a week of obtaining the tusk samples. The interactive tool itself only takes a few seconds to generate results.
This simpler and quicker approach will enable scientists to extract and sequence DNA locally from any confiscated tusks and add their results to the database.
Local laboratories will be able to do their own forensic analysis without relying on shipment of elephant or ivory samples outside their own countries, which Roca notes can be complicated in terms of permits and logistics.
He hopes this method will add to the multiple approaches necessary to reduce supply and demand of ivory and put an end to poaching and trafficking.
The study is published in the Journal of Heredity.