**4. Conclusions**

In nearly two decades since DNA barcodes were first proposed, a remarkable increase has taken place in the representation, use, and integration of DNA barcodes across the biological sciences. Although sequence variation in traditional DNA barcodes is often insufficient for species-level discrimination in many large clades, the advances in computational and sequencing technology are changing the concept of DNA barcodes, from just a few loci to large, genome-scale sequences from organelles or genome-skim data. As technology expands and genome sequence representation increases across the Tree of Life, we envision a future in which the concept of DNA barcodes extends to a much larger interpretation of genome space. DNA barcoding continues to evolve with methodological and technological advances in conjunction with the increasing accessibility to high-throughput sequencing and the growing database of whole genome sequences fostered through international consortia, such as the Earth BioGenome Project [37,38]. A diversity of genetic tools is especially needed in clades, such as green plants, with highly complex genomes that require significant resources to assemble [205]. Until there is a corresponding breakthrough in computational capacity for the comparative analysis of large and highly complex genomes, DNA barcode sequences will play a vital role for species identification in community ecology, evolutionary biology, and conservation. DNA barcodes are a powerful resource

and the databases that maintain them continue to grow as they complement and benefit from the rapidly expanding frontiers of computational science and high-throughput sequencing technology.

**Author Contributions:** Both authors contributed equally to this publication. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Institutional Review Board Statement:** Not applicable.

**Data Availability Statement:** Not applicable.

**Acknowledgments:** The authors acknowledge the diversity of contributions made by the hundreds of scientists from around the world to the field of DNA barcoding over the last decades. We are especially grateful to the Smithsonian Institution Barcode Network, the Global Genome Initiative, and the Consortium for the Barcode of Life which have supported our own research.

**Conflicts of Interest:** The authors declare no conflict of interest.
