DNA barcoding helps discover new species

By Kirtiman Awasthi
Published: Tuesday 15 May 2007

through genetic analysis, scientists have established that the clouded leopard found on Borneo island is a new species--Neofelis diardi--of cat. Earlier, the species was thought to belong to a group of leopards found in mainland south-east Asia. According to the us National Cancer Institute, which carried out the genetic analysis, dna tests highlighted around 40 differences between the species. The results of dna analysis show that the Borneo population diverged from the mainland population some 1.4 million years ago.

Genetic differences aside, the species of leopards have different physical characteristics as well--different fur patterns and skin colouration. The Borneo clouded leopard has small cloud markings with distinct spots within them, grey fur and a double dorsal stripe.There had been a separate study on geographical variations in the clouded leopard, based primarily on fur patterns and skin colouration, and the results match those of the genetic tests.

"We didn't realise that this animal was unique. The fact that Borneo's top predator is now considered a separate species emphasises the importance of conserving biologically diverse habitats," says Stuart Chapman, wwf International Coordinator of the Heart of Borneo programme.

The example of the Borneo clouded leopard, however, is only a case in point. With the science of taxonomy getting more and more advanced, along with dna barcoding technique (see box: Barcoding life), a host of new species have been discovered, including marine organisms. A wwf report earlier revealed that scientists had identified at least 52 new species of animals and plants in 2006 in Borneo. Recently, two Canadian studies (Molecular Ecology Notes; Vol 7, No 2, March, 2007) provided evidence of six new species of bats and 15 species of North American birds (from existing known species) using dna barcoding.

dna barcoding identifies living beings by genetic composition rather than appearance, although not all species are identified using this technique. Some biologists do not agree that barcoding has expedited discovery of species. "We need to keep clear the difference between species discovery and species identification.Species discovery is the process of classical taxonomy (based on morphology, physiology and ecology)," says Rob DeSalle, biologist at the American Museum of Natural History, New York, usa. "Genetic analysis only augments classical taxonomy."

In the Canadian studies, 95 per cent of cases examined, entities recognised as species through conventional taxonomy were barcode distinct. "The new tool is helpful indiscovering less charismatic species," says Mike Hickerson, associate professor at the Department of Biology, Queens College, City University, New York. Hickerson argues that dna barcoding methods are not 'causing' an upsurge in discovery. He feels that many of these are due to increased survey efforts in remote parts of the world. "However, many of these new cases are likely to be verified with dna sequence data," say Hickerson.

Varad Giri, a researcher with the Bombay Natural History Society, agrees. Giri recently discovered two new species--one belonging to group of limbless amphibians and the other, a lizard. He faces problems with identification of cryptic species where no data is available to work on. "This is where genetic analysis can help," he says.

But experts agree that with greater advancement in the science of species discovery and identification, conservation efforts will be improved by allowing environmentalists to better track species, helping tropical countries with dense, unexplored forests decide which areas to protect.

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