Does One Size Fit All? Variations in the DNA Barcode Gaps of Macrofungal Genera

Area of Science:

• Mycology
• Molecular Biology
• Genetics

Background:

• The nuclear ribosomal internal transcribed spacer (nrITS) region is a key DNA barcode for fungal diversity and distribution studies.
• Environmental metabarcoding highlights the need for robust fungal DNA barcoding practices.
• Limited understanding of the DNA barcode gap in macrofungi hinders accurate species delineation.

Purpose of the Study:

• To examine the DNA barcode gap within the nrITS region of macrofungi.
• To investigate factors influencing barcode gap size, including sequence variance and taxonomic approaches.
• To assess the implications for quantifying fungal species richness and taxonomic studies.

Main Methods:

• Analysis of 5146 nrITS sequences from 717 macrofungi species.
• Measurement of intra- and inter-specific pairwise distances using sequence and phylogenetic data.
• Comparison of barcode gap variations between ITS1, ITS2, and combined nrITS regions.

Main Results:

• Barcode gap size is influenced by intra- and inter-specific variance.
• The ITS2 region exhibits greater barcode gaps than ITS1 due to higher variance.
• Taxonomic 'splitting' yields larger barcode gaps compared to 'lumping'.

Conclusions:

• Variability in nrITS barcode gaps necessitates careful consideration for species richness estimation.
• Understanding barcode gap behavior is essential for accurate fungal DNA barcoding.
• Multiple molecular markers are recommended to corroborate species delineation in taxonomic studies.