Interlaboratory study to assess the practical utility of OSAC proposed standard 2021-S-0006: Standard for the use of GenBank for taxonomic assignment of wildlife

Abstract

Wildlife forensic laboratories are frequently asked to confirm the taxonomic identity of material submitted as evidence. When taxonomic assignment based on morphology is not possible, DNA-based approaches are typically employed and practitioners often rely on comparing unknown evidence sequences to public sequence databases such as GenBank. To address the use of GenBank in casework, the Organization of Scientific Area Committees for Forensic Science (OSAC) Wildlife Forensic Biology Subcommittee developed 2021-S-0006 Standard for the Use of GenBank for Taxonomic Assignment of Wildlife (currently an OSAC proposed standard). An interlaboratory study was conducted to assess the practical utility of 2021-S-0006. Sanger sequence data for taxonomically informative mitochondrial loci from forty diverse wildlife species were generated. Eleven wildlife forensic laboratories across the globe were recruited, and were sent ten unknowns to analyze using 2021-S-0006. Taxonomic assignments generated by each laboratory were compared a) to the true identity to determine correctness, and b) across laboratories to assess congruence. When following 2021-S-0006, laboratories that reported to the species level were correct in 98.3% of cases and 100% congruence was observed among laboratories. Additionally, criteria selected by laboratories for interpreting GenBank accession(s) (section 4.3 of 2021-S-0006) were independently evaluated, given they form the backbone for determining the appropriate level for taxonomic reporting. Criteria were correctly selected in 84% of cases and laboratories reported to an appropriate taxonomic level in the majority of cases. Overall, this interlaboratory study demonstrated that the OSAC proposed standard 2021-S-0006 provides an excellent framework for using GenBank for taxonomic assignment in wildlife forensic casework.