DNA barcoding study retracted after co-author raises concerns about its validity

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Biodiversity and Conservation retracted a 2014 article co-authored by Ken A. Thompson and Steven G. Newmaster, PhD, titled “Molecular taxonomic tools provide more accurate estimates of species richness at less cost than traditional morphology-based taxonomic practices in a vegetation survey.” That article made the case for DNA barcoding as a more reliable and cost-effective method of identifying plant species than traditional morphology-based taxonomic practices. The article was retracted after Thompson raised concerns about the data source and reproducibility. Upon post-publication review, the publication’s editor-in-chief confirmed concerns about data availability and the validity of data included in the article.

Thompson was an undergraduate student at the University of Guelph in Ontario, Canada when he wrote the paper, using data from Newmaster, who is a professor of botany at the Department of Integrative Biology at the University of Guelph. The major issues raised by Thompson were that the DNA data was not posted at the time of the article’s publication, and that when the data was uploaded eventually in September 2020, review of this data was unable to confirm that it was actually derived from the research described in the article, nor did it support the paper’s conclusion. An article published in Science provides more detail on Thompson’s efforts to disavow the study he co-authored. Newmaster did not respond to correspondence from Biodiversity and Conservation’s editor or publisher on the retraction.

Newmaster’s work is well known to the industry because of a different study he authored in 2013 published in BCM Medicine, using DNA barcoding. That study found DNA barcodes from plant species not listed on the labels of 59% of 44 herbal products sampled, as well as contaminants and fillers not listed on labels of one third of these products. This paper was widely criticized by industry. In a letter to the journal’s editor, Michael McGuffin, president of the American Herbals Products Association (AHPA; Silver Spring, MD), identified inaccuracies and stated that “blanket assertions about the accuracy of this novel analytical tool are premature.” The American Botanical Council (ABC; Austin, TX) went so far as to publish an in-depth review critiquing the article and calling on Newmaster to retract it.

Ultimately, the 2013 article became the basis for New York Attorney General Eric Schneiderman’s decision to issue cease and desist letters to makers of devil’s claw supplements sold in the state. These actions led to negative press challenging the quality and integrity of the herbal products industry and greater regulatory burden on dietary supplement companies.