Beyond DNA barcodes: an open-source workflow for recovering and organizing barcoded vouchers for ecological and evolutionary research

Abstract

1. Most species are neither discovered nor named, let alone included in analyses that require biological information such as trait measurements, images, ecological information and genome-scale data. Specimen-level DNA barcoding can help discover many of these species rapidly, but everything beyond discovery requires vouchers organized into putative species. Yet, existing barcoding workflows lack efficient techniques for voucher recovery, creating a post-barcoding bottleneck that limits the ability of converting barcoded specimens into biological knowledge. 2. Here we present a low-cost, open-source workflow consisting of two stages. The first safeguards barcoded specimens by separating them from DNA extracts and transferring them from microplates into ethanol-filled glass vials. The second converts the resulting voucher collection into a searchable physical resource by linking barcode-derived molecular Operational Taxonomic Unit (mOTU) assignments to vial positions and enabling specimens to be sorted into putative species either manually or automatically using a newly developed open-access robot (SORTER). 3. We evaluated the workflow using 2,024 insect specimens distributed across 21 96-well plates. For the first stage, DNA separation and specimen transfer required approximately 15 minutes per plate. For the second stage, MOTUmapper generated retrieval coordinates in a few seconds, after which the 2,024 vouchers belonging to the 452 putative species could be recovered manually in 5 days or with SORTER in 5 hours. Throughout both stages, specimen identities remained linked to barcode sequences, metadata and storage positions. 4. Vouchers are the Rosetta stones of biology because they connect different kinds of data to the same specimens. By safeguarding these vouchers and making them searchable, the workflow converts barcode projects from one-time molecular surveys into reusable resources for ecological and evolutionary research.