Published in September 2019
This module is a resource for lecturers
DNA testing is sometimes used in investigations of wildlife trafficking. DNA evidence is often of paramount importance as most cases require that the animal or plant in question needs to be identified in order to establish whether it is part of a defined, protected group. DNA is particularly useful in cases in which a sample's species, origin, or identity cannot be determined on a purely morphological basis. This may be the case, for instance, where a sample contains only a part of an animal, is in an immature state (such as an embryo), or has been processed into a product or derivative. Additionally, DNA can assist in establishing whether an animal was captive-bred or wild-sourced or to differentiate between look-alike species. In these circumstances, DNA essentially serves to identify whether the subject was sourced and traded legally or illegally.
Compared to human DNA testing and analysis, DNA testing of animals and plants remains underdeveloped and underfunded. Forensic laboratories usually dealing with human DNA are sometimes unable or unwilling to accept, test, or prioritize animal or plant DNA. In many places, DNA analysis of animal and plant samples is outsourced to non-government entities (Linacre & Tove, 2013; Iyengar, 2014). If DNA testing is done outside accredited forensic laboratories without qualified or certified staff, the rigorous standards expected of DNA may be not consistently applied and evidence may become inadmissible in court proceedings (Ogden, 2010). In some States, such as the United States, bodies for the accreditation of wildlife laboratories have been set. The Society for Wildlife Forensic Science (SWFS) also offers proficiency testing to accredited laboratories in the United States, and membership in the society is offered to laboratories in other countries.
Methods in wildlife DNA analysis
DNA may be extracted from a wide range of biological material such as blood, meat, urine, faeces, skin, hair, scales, bone, feathers, claws, teeth, shells, scales, venom and embryonic tissue, as well as processed products such furs, leather goods, and medicines (Iyengar, 2014; see also, Byrd & Sutton, 2012).
Unlike human DNA analysis, for each relevant animal or plant species, a new methodology and set of genetic markers needs to be developed, mapped, and validated. Validation entails testing to ensure that the technique developed yields an accurate and reliable result (see, for example, Scientific Working Group on DNA Analysis Methods (SWGDAM), 6 July 2004).
Field of application
DNA testing can be used in various ways to assist in the investigation of wildlife trafficking.
In the investigation of wildlife trafficking, DNA testing is most commonly used in species identification (Ogden, 2012). This relies on genetic markers which are consistent within a species, but which vary between species (see, for example, Dalebout et al, 2008; Shivji et al, 2005).
Identification of geographic origin
In some cases, and for some offences, it is necessary to identify the geographic location from which a sample originates. This is the case, for instance, to find out if fish was caught in protected zone or if an animal was poached in a protected area. Using DNA for this purpose requires sufficient genetic variation between geographically distinct populations, as well as reference data from a variety of potential source populations (Ogden, 2012; for examples, see Ghobrial et al, 2010; Wasser et al, 2004). For these reasons, it may be difficult to carry out this procedure where a species is almost extinct and reference data is rare. If, on the other hand, a species exists in abundance, the use of DNA can lead to successful prosecutions, as reports involving cases of illegal salmon fishing show (Withler et al, 2004; Seeb et al, 2007).
Example: DNA testing to reveal Africa's major poaching hotspots
To identify the number and location of Africa's major poaching hotspots, researchers genetically assigned the origin to 28 large ivory seizures (≥0.5 metric tons) confiscated between 1996 and 2014. Their results suggest that the major poaching hotspots in Africa may be concentrated in as few as two areas. Between 86 and 93 percent of the savanna elephant ivory was predominantly assigned to Southeastern Tanzania and adjacent northern Mozambique; 86 to 93 per cent of the forest elephant ivory was predominantly assigned to the Tridom area bordering northern Gabon, Republic of Congo and southwestern Central African Republic. Based on these findings, it is believed that increasing law enforcement in these two hotspots could help curtail future elephant losses across Africa and disrupt this transnational organized crime.
(Wasser et al., 2015)
Although less common in wildlife trafficking investigations, in some cases, it may be possible or necessary to match DNA found at a crime scene to a specific animal or plant. This may be the case, for instance, where a seized piece of tiger may be traced to the carcass of a tiger killed at a zoo (Gupta et al, 2011). Other applications of this technique include the authentication of legal animal products (Ogden, 2012; Palsbøll et al, 2006; Hogg et al, 2018).
Individual identification, or DNA profiling, relies on genetic markers that have a high level of variability within a given species, and are thus likely to differ between individuals. This technique is effective to determine where two samples are not from the same individual; however, where two samples produce the same profile, this is only a suggestion that they originate from the same individual. The possibility of closely related samples and inbred populations may be difficult to displace in some cases.
Identification of suspects
As is the case in conventional crimes, analysis of human DNA can be used for the identification of suspects. In some cases, DNA of the perpetrator can be recovered at the crime scene, sometimes even from animal or plant products (for a case study, see Tobe et al, 2011).