A DNA-Based Registry for All Animal Species: The Barcode Index Number (BIN) System

TLDR

Many animal species remain undescribed and species identification is difficult, so biodiversity studies rely on operational taxonomic units (OTUs) that can be defined morphologically or, increasingly, by DNA, offering faster and more reliable species delineation. The study aims to create a persistent, species‑level registry for all animals by analyzing COI barcode variation. The authors compare COI‑based OTU assignments from RESL and four other algorithms to traditional species identifications, then implement the Barcode Index Number (BIN) system, which automates OTU designation, archives data, and facilitates cross‑study comparisons. BINs support biodiversity assessment and taxonomic revision by flagging synonymy and aggregating specimen metadata, and the system already hosts over 274,000 web pages, poised for rapid expansion.

Abstract

Because many animal species are undescribed, and because the identification of known species is often difficult, interim taxonomic nomenclature has often been used in biodiversity analysis. By assigning individuals to presumptive species, called operational taxonomic units (OTUs), these systems speed investigations into the patterning of biodiversity and enable studies that would otherwise be impossible. Although OTUs have conventionally been separated through their morphological divergence, DNA-based delineations are not only feasible, but have important advantages. OTU designation can be automated, data can be readily archived, and results can be easily compared among investigations. This study exploits these attributes to develop a persistent, species-level taxonomic registry for the animal kingdom based on the analysis of patterns of nucleotide variation in the barcode region of the cytochrome c oxidase I (COI) gene. It begins by examining the correspondence between groups of specimens identified to a species through prior taxonomic work and those inferred from the analysis of COI sequence variation using one new (RESL) and four established (ABGD, CROP, GMYC, jMOTU) algorithms. It subsequently describes the implementation, and structural attributes of the Barcode Index Number (BIN) system. Aside from a pragmatic role in biodiversity assessments, BINs will aid revisionary taxonomy by flagging possible cases of synonymy, and by collating geographical information, descriptive metadata, and images for specimens that are likely to belong to the same species, even if it is undescribed. More than 274,000 BIN web pages are now available, creating a biodiversity resource that is positioned for rapid growth.