Taxonomy is revamped in DNA-based system

In 1735, Carl Linneaus proposed a system for naming organisms in his publication Systema Naturae. This system, called Linnaean taxonomy, has proven robust as it is still used today, nearly 300 years after its original proposal. In this taxonomy, each organism is divided into one of three kingdoms, then further classified into different classes, orders, families, genera and species.

While there have been some updates to this method of taxonomy due to discoveries of new categories of organisms, the fundamental method proposed by Linneaus has not changed. In addition to the taxonomic system, Linneaus’ binomial nomenclature has remained alive as the most prevalent method of scientific naming.

Since the 18th century, many new organisms have been identified. Scientists were first able to accommodate the increasing level of detail in species distinctions by creating categories of subspecies. However, as the number of classified organisms grew, it became increasingly difficult to work with the Linnaean method. Unicellular organisms were particularly problematic, as they often shared physical characteristics despite their drastically different lineages.

To address the issues associated with the current classification system, Boris Vinatzer of the Virginia Polytechnic Institute and State University recently proposed an update to Linnaean taxonomy. Vinatzer claims that his method, which will name organisms based on genetic sequence rather than physical characteristics, is more specific than Linnaeus’s system and will lead to standardized naming system for all forms of life. This genome-based system will be especially useful in naming physically indistinguishable unicellular organisms.

Vinatzer, an associate professor in plant pathology, physiology and weed science, points out that Linnaean taxonomy was created in a time when plants, animals and minerals were still being categorized and named. As a larger number of unicellular organisms such as protists and fungi are discovered, it becomes increasingly difficult to find distinguishing physical characteristics for proper classification.

Vinatzer cites anthrax as an example of the limitations associated with the Linnaean system. Although more than 1200 strains of anthrax have been discovered, they remain virtually indistinguishable on paper, as they are often given arbitrary names that do not elucidate any defining traits. With Vinzter’s new system, anthrax strains could be classified clearly by their genome identities. For example, the anthrax agent used in bioterrorist attacks could be named lvlw0x, while its known ancestor strain could be named lvlwlx, highlighting the existing differences between the two strains.

Vinatzer thinks that genome sequences would strengthen the current system of biological classification by allowing scientists to categorize new organisms under existing species. This would displace the need for subspecies. Vinatzer’s new system will also expedite the current naming process. Scientists will no longer need to search for indiscernible physical differences between organisms —ß they can simply map genomes and name organisms according to the readout.