A Plea for Standardized Nuclear Markers in Metazoan DNA Taxonomy. Trends in Ecology & Evolution.

The ease of sequencing DNA barcodes promoted a species identification system
universally applicable across animal phyla. However, relying on a single mitochondrial
DNA fragment has a number of drawbacks that can mislead species
delimitation and identification. Implementation of multiple nuclear markers
would mitigate the limits of the current barcoding system if these markers are
universally applicable across species, carry sufficient information to discriminate
between closely related species, and if sequencing and analyzing these markers
can be automatized. As sequencing costs continue to fall, we believe that the
time is right to extend DNA barcoding. Here we argue that nearly universal
single-copy nuclear protein-coding genes deliver the desired characteristics
and could be used to reliably delimit and identify animal species.