The ITS region is the most widely sequenced DNA region in molecular ecology of fungi[5] and has been recommended as the universal fungal barcode sequence.[6] It has typically been most useful for molecular systematics at the species level, and even within species (e.g., to identify geographic races). Because of its higher degree of variation than other genic regions of rDNA (for small- and large-subunit rRNA), variation among individual rDNA repeats can sometimes be observed within both the ITS and IGS regions. In addition to the standard ITS1+ITS4 primers[7] used by most labs, several taxon-specific primers have been described that allow selective amplification of fungal sequences (e.g., see Gardes & Bruns 1993 paper describing amplification of basidiomycete ITS sequences from mycorrhiza samples).[8]