CBOL protist working group: barcoding eukaryotic richness beyond the animal, plant, and fungal kingdoms

Abstract

A group of protist experts proposes a two-step DNA barcoding approach, comprising a universal eukaryotic pre-barcode followed by group-specific barcodes, to unveil the hidden biodiversity of microbial eukaryotes.

Figure 1. Morphological versus genetic views of total eukaryotic diversity.

(A) Relative numbers of described species per eukaryotic supergroup—see Table S1 for a detailed count per division/class. (B) Relative number of V4 18S rDNA Operational Taxonomic Units (97%) per eukaryotic supergroup, based on 59 rDNA clone library surveys of marine, fresh-water, and terrestrial total eukaryotic biodiversity (as listed in [55]).

Figure 2. Current state-of-the art phylogeny and barcode markers for the main protistan lineages.

(A) A recent phylogeny of eukaryotic life, after . (B) Mean V4 18S rDNA genetic similarity between all congeneric species within each lineage, available in GenBank. (C) Currently used group-specific barcodes. The dashed line indicates the incertitude concerning the position of the root in the tree of eukaryotic life. The unresolved relationships between eukaryotic groups are indicated by polytomies. The names of the three multicellular classical “kingdoms” are highlighted.

Figure 3. Two-step protist barcoding pipeline.

Protistan species, spanning four orders of cell-size magnitude (from <1 µm to >10,000 µm), are individually sorted from the environment, phenotyped either directly or after culture growth, DNA extracted, and barcoded using a two-step, nested strategy.