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Headlines Published on 20 October 2004

Title DNA sampling boosts animal conservation and taxonomy

Recent research, reported by Nature News, is seizing on developments in DNA recording techniques. North American scientists are using this genetic data to track animal movements and to identify quickly specific species and, in the case of African elephants, even where they come from.

DNA information helps track animals in Africa © Image: PhotoDisc
DNA information helps track animals in Africa
© Image: PhotoDisc
Genetic information from smuggled ivory could help police and conservationists identify black spots where elephants face greater risk from poachers. US scientists studied the DNA of elephant droppings collected from 28 locations across Africa in order to build a ‘genetic map’ of the possible variations.

Reporting their findings in the Proceedings of the National Academy of Sciences (PNACS), Sam Wasser of the University of Seattle and colleagues says they can now tell apart elephants from different forests and savannahs in west and central Africa with almost 100% accuracy. The difference between eastern and southern populations is less pronounced, but he says their testing methods can still locate these populations with around 80% accuracy.

But what is the use of tracing seized ivory back to a specific location when the crime has already taken place? Since the ivory trade was banned in 1989, poachers have become much more stealthy, taking their activities from open savannahs – where these endangered beasts are protected by aerial surveillance – out of sight in the dense bush and forests. Ground patrols have proven less than reliable in curbing the slaughter. Killings can go unnoticed for years. But the new tool can immediately locate the regions where elephants face the greatest risk.

Easy-to-read labels
In a related development reported by Nature News, scientists are getting closer to using DNA sequencing to tell different animal species apart – what experts are calling ‘DNA barcoding’. If successful, there are many applications for an easy-to-use, animal identification and labelling system. Researchers in remote locations, for example, could use a scanner much like a supermarket checkout system to log a species instantly. Customs at airports and docks could relatively quickly identify illegally smuggled fauna or potentially unwelcome insects hiding among the cargo or ballast waters.

Current methods and technologies for doing this are slow and ineffective, based often on visual charts and physical measurements being taken of animal features such as, in the case of birds, beak shape or wing colour. But with DNA barcoding, the scientists describe 650 letters in the genetic sequence of a single telltale gene – the cytochrome coxidase I. This gene tends to vary a lot between species, notes the article ‘DNA barcodes tag species’, which makes it a good candidate for distinguishing species relatively accurately.

However, some researchers remain sceptical of the utility of this method. To prove the idea works, Canadian scientists, led by Paul Herbert of Guelph University, read and compared the DNA codes from museum specimens of 260 different North American bird species. Not only did they have different barcodes, they also suspect (see also PNACS report) that all of the samples fall into four super groups. 

Two other advantages have been noted in using DNA barcoding over traditional approaches. First, it requires only a fragment of tissue or shell and, if the barcode readers become available, they can be used by amateur taxonomists and professionals alike. But the critics are afraid this ease of use may threaten age-old methods of taxonomy. “And even supporters [of the system] acknowledge that [it] will struggle to distinguish species whose genetic sequence is extremely similar, such as the ones that have only recently diverged from one another,” the article notes.

Source:  Nature News

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More information:

  • Genetic map pinpoints elephant poachers (Nature News, 27 September 2004)
  • DNA barcodes tag species (Nature News, 27 September 2004)

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