The illegal trade of wildlife (plants, animals, and their byproducts) is the second largest threat facing endangered species today, outranked only by habitat destruction. Frequently trafficked species span all ecosystems in every part of the world, making the $20 billion/year market incredibly difficult for law enforcement to handle. Most trade occurs along existing drug smuggling routes, and once wildlife is seized, it’s often tough to pinpoint where exactly these species came from– that’s where molecular genetics comes in.
Turtles are one of the most threatened species worldwide, with 51% of their species extinct, endangered, or vulnerable of becoming endangered. (Image source)
In the past, identifying trafficked organisms was based primarily on recognizing physical traits unique to each species. Unfortunately, this requires the plant or animal to be mostly intact, and is almost useless in identifying the origins of byproducts often seized (such as ivory, cooked/dried meats, feathers, etc.); however, molecular approaches require only a small sample of DNA, making them the preferred method of species identification in these instances.
Each cell contains multiple copies of mitochondrial DNA (mtDNA) because there are several mitochondrion inside. Plant and animal cells only contain one nucleus a piece (generally), meaning that mtDNA is more likely to be found in a sample (like decomposing tissue) than nuclear DNA (nDNA). Segments of mtDNA can be copied over and over again using a process known as the polymerase chain reaction (PCR), which allows genes (like Cyt b or CO1) to be identified easily. The differences in DNA patterns within these genes is what makes each species unique– that’s how they’re able to be identified.
Having multiple mitochondrion in each cell makes mtDNA the preferred genetic marker for identifying a degraded sample’s species of origin. (Image Source)
In terms of conservation efforts, simply identifying a species isn’t enough– it’s important to determine where these organisms are starting their trafficked journey. “Phylogeography” refers to the relationship of very similar genetic patterns (like those found in mtDNA) and their location across the globe. A species’ region of origin can be determined by comparing it’s mtDNA sequences to what we already know about the mtDNA of similar species living in different parts of the world.
Phylogeographic methods were used to compare seahorse species Hippocampus barbouri, H. spinosissimus (pictured here), H. trimaculatus, and H. ingens to pinpoint the birthplace of seahorses listed for sale in Californian traditional medicine shops. (Image Source)
Not only is the trafficking of species cruel to individual organisms, it disrupts their home ecosystems by removing key players from their natural balance, while simultaneously exposing species to foreign diseases they have no immunity against. The methods described above, in part with harsher legal consequences for traffickers, can help decrease illegal wildlife trade, therefore improving the overall health of species everywhere.
Source: Alacs, et al. (2009). DNA detective: a review of molecular approaches to wildlife forensics. Forensic science, medicine, and pathology. DOI: 10.1007/s12024-009-9131-7.