Intraspecific ITS Variability in the Kingdom Fungi as Expressed in the International Sequence Databases and Its Implications for Molecular Species Identification
Journal article, 2008

The internal transcribed spacer (ITS) region of the nuclear ribosomal repeat unit is the most popular locus for species identification and subgeneric phylogenetic inference in sequence­based mycological research. The region is known to show certain variability even within species, although its intraspecific variability is often held to be limited and clearly separated from interspecific variability. The existence of such a divide between intra and interspecific variability is implicitly assumed by automated approaches to species identification, but whether intraspecific variability indeed is negligible within the fungal kingdom remains contentious. The present study estimates the intraspecific ITS variability in all fungi presently available to the mycological community through the international sequence databases. Substantial differences were found within the kingdom, and the results are not easily correlated to the taxonomic affiliation or nutritional mode of the taxa considered. No single unifying yet stringent upper limit for intraspecific variability, such as the canonical 3 % threshold, appears to be applicable with the desired outcome throughout the fungi. Our results caution against simplified approaches to automated ITSbased species delimitation and reiterate the need for taxonomic expertise in the translation of sequence data into species names.

ribosomal dna

phylogenetic inference

transcribed spacer regions


ectomycorrhizal fungi

medically important yeasts


dna barcodes




R. Henrik Nilsson

University of Gothenburg

Erik Kristiansson

Chalmers, Mathematical Sciences, Mathematical Statistics

University of Gothenburg

Martin Ryberg

University of Gothenburg

Nils Hallenberg

University of Gothenburg

Karl-Henrik Larsson

University of Gothenburg

Evolutionary Bioinformatics

1176-9343 (ISSN)

Vol. 2008 4 193-201

Subject Categories

Biological Systematics

Biochemistry and Molecular Biology


Biological Sciences

Bioinformatics and Systems Biology



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