Historic DNA extraction: genetic potential of chiton museum specimens

Abstract DNA barcoding using the cytochrome c oxidase subunit I (COI) fragment plays an important role in taxonomy, due to its efficiency and reliability in species identification. This targeted method enables comparisons with extensive existing datasets, facilitating the identification of unknown species and the verification of known ones. While next-generation sequencing (NGS) technologies have revolutionised genetic research, they remain costly and often require extensive bioinformatics expertise. Although barcoding still requires specialised knowledge, it remains comparatively more accessible and cost-effective; however, it depends on intact DNA for the barcode region, posing a challenge for rare and historical museum specimens where DNA is often degraded. Recent molecular advances have expanded the potential for genetic studies on historic specimens, but DNA degradation and contamination remain significant hurdles. In this study, we tested a process to optimise DNA extraction from chitons, a group of marine invertebrates often preserved as whole-body dry specimens in museum collections. The study aimed to obtain short COI barcodes by designing chiton-specific COI primers to assist with species identification. We successfully sequenced mitochondrial fragments from historical specimens up to 140 years old. Comparisons indicate that age is not a reliable predictor of success or failure. This approach could be particularly valuable for genetic research on aquatic and soft-bodied invertebrates with dry-preserved specimens, where DNA degradation poses significant challenges.