Can DNA forensics be used to combat the ivory trade?

By Laura Upton

The illegal poaching of large mammals for trade, in particular the elephant for the ivory trade, has been a concerning issue in conservation for a long time. Both the African elephant (Loxodonta Africana) and the Asian elephant (Elephas maximus) are illegally poached for their tusks and are listed as threatened on the IUCN red list; the Asian elephant is endangered and the African elephant is vulnerable[1]. Elephant ivory has historically been a luxury material with a high market value. It is often carved into ornamental trophies ranging from piano keys, decorative boxes and religious objects to false teeth. The demand for illegal ivory comes from all over the world, including Asia, Europe and the USA[2]. The high demand and market value for ivory is leading to an increased level of illegal poaching, which is obviously becoming uncontrollable. Poachers are known to attack whole herds of elephants with automatic weapons then brutally cut the ivory from the bodies with axes and chain saws[2]. Tens of thousands of elephants are killed in this way every year. In the years between 2008 and 2013 the number poached each year ranged from 30,000 to 50,000 resulting in an estimated 240,000 elephants killed for their ivory tusks[2].

Three of the largest seizures of ivory since the trade ban have occurred since June 2002[3]; the largest of which being a 6.5 tonne seize in Malawi. This seize was heading to the Far East after being shipped from Zambia in small amounts[4]. The 6.5 tonne seize was made up of 532 tusks, weighing an average of 11kg, and 42,120 hankos (6.5cm long, hollow cylinders of ivory). This number of hankos is worth around $8.4 million[4] which is over 20% of Japan’s annual hanko trade. The tusks seized were stained different colours from the soil they were buried in and were marked with different writing such as ‘YOKOHOMA’ and ‘ALA’[4]. These differences indicate that there were multiple participating groups in the poaching. Regulation of the ivory trade could be improved vastly by knowing from where the ivory originates. A recent study testing the effectiveness of DNA tracing had promising results; 50% of the ivory samples were located within 500km and 80% within 932km of the true place of origin[3]. Information like this is valuable for local authorities in deciding where to increase law enforcement and can help international decisions regarding sanctioning their legal trade[3]. A DNA map of elephant herds in Africa was constructed using DNA extracted from elephant faeces in a number of locations. This DNA was then compared with mitochondrial and microsatellite DNA extracted from the tusks seized[3]. The DNA was amplified using PCR (the polymerase chain reaction) at 40 cycles and then analysed using an automated DNA sequencer[4].

There are two groups of elephants in Africa, forest and savannah. When using this method to locate the origins of the ivory all the samples from forest elephants were accurate. This is explained by different herds of elephants in forestry habitats being separated by physical obstacles. This limits the mating of the elephants to within their individual herds, ensuring they remain genetically different. However, in the savannah the results were less accurate. The results were still promising however, with the real locations of the ones misplaced being in neighbouring areas[3].

Using this method, the 6.5 tonne seize was sampled and analysed to find the location of the poaching. 67 of the 532 tusks recovered were divided into groups using the stain colour and the marks to allocate[4]. From these only 37 had successful amplification of their DNA[4] using the method described above. It was found that all the ivory originated from a narrow strip reaching east to west across southern Africa, centring on Zambia, seen in Fig. 1.

Figure 1[4]: The location results for the 37 tusks analysed from the seizure. (A) is the origins compared with reference samples, (B) is without reference samples. The additional reference samples used for confirmation are from Zambia, Malawi and Tanzania. It is seen that the origins of the ivory are the same with and without the references.

Figure 1[4]: The location results for the 37 tusks analysed from the seizure. (A) is the origins compared with reference samples, (B) is without reference samples. The additional reference samples used for confirmation are from Zambia, Malawi and Tanzania. It is seen that the origins of the ivory are the same with and without the references.

These techniques can be applied to many more aspects of illegal trading and conservation. Elephants are not the only species that experience brutal poaching for their valuable features. Another large mammal targeted brutally is the Rhinoceros, for its horn. The rhinoceros species poached for horns are the two African Rhinos: the black rhinoceros (Diceros bicornis) and the white rhinoceros (Ceratotherium simum), and the Asian rhinoceros (Rhinoceros unicornis). Rhino horn has two main uses: ornamental and medicinal. A rhinoceros horn is a beautiful object composed of keratin, a protein also found in hair and nails. The end of the horn is shiny, condensed, hard and black, contrasting with the less dense middle, which if sliced and held up to the light has a translucent amber glow[5]. Rhino horn has been valued in traditional Chinese medicine for thousands of years; it was referred to as the ‘divine peasants herbal’ in a Chinese text dating back 2000 years[5]. Rhinoceros poaching has increased dramatically since 2007; 2013 was the worst year recorded with over 1,000 rhinos being poached. Using DNA tracking of horns could have the same benefits in conserving the species as it does in elephants. The black rhino is listed as critically endangered on the IUCN red list[1] and if poaching isn’t prevented this species could easily become extinct in the wild.

DNA forensics is a powerful tool in combating illegal poaching of species across the globe. Compared to the costs of other conservation actions the sampling of tusks is low; the cost of analysing a tusk and locating its origin is near $100[3]. This cost is likely to decline in the future as sampled areas do not need resampling. Governments using data found from these analyses can concentrate efforts on the areas of highest poaching and hopefully these species can be saved before we lose them forever to poaching and greed.

  1. The IUCN Red List of Threatened Species. 2014 [cited 2014 2/12]; 2014.3:[

  2. Foundation, B.F. Born Free Foundation: The Ivory Trade. 2014 [cited 2014 2/12].

  3. Wasser S. K., S.A.M., Comstock K., Ostrander E. A., Mutayoba B. & Stephens M., Assigning African elephant DNA to geographic region of origin: Applications to the ivory trade. PNAS, 2004. 101(41): p. 14847-14852.

  4. Wasser S. K., M.C., Booth R., Mutayoba B., Kisamo E. & Clark B., Using DNA to track the origin of the largest ivoryseizure since the 1989 trade ban. PNAS, 2007. 104(10): p. 4228-4233.

  5. Emslie, R.a.B., M., African Rhino. Status Survey and Conservation Action Plan. IUCN/SSC African Rhino Specialist Group., 1999.

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