Abstract
Because of Canada’s large size, it is impractical to obtain a comprehensive perspective on biotic change through morphological approaches. DNA metabarcoding offers a potential path, but its application requires access to a well-parameterized DNA barcode reference library. This study presents the current state of DNA barcode coverage for Canadian animals, highlighting progress, identifying gaps, and providing recommendations for future research. Our analysis indicates that many of the known species (100 000 terrestrial and 6000 marine) in the Canadian fauna possess DNA barcode coverage, but there are important gaps geographically and taxonomically. We summarize DNA barcode coverage for the species in freshwater, marine, and terrestrial environments by ecoregion, finding that 95.6% of the 2.3 million Canadian barcode records derive from terrestrial ecosystems. Although the density of barcode records per 100 km² is 13x higher for terrestrial than aquatic environments (22.4 vs. 1.7), coverage for 58% of marine species is available (54% for annelids, 52% for arthropods, 88% for chordates, 39% for echinoderms, and 46% for molluscs). By revealing data-deficient areas and taxonomic groups, this study offers a roadmap for expanding the DNA barcode library for the Canadian fauna as an essential foundation for the scalable biosurveillance initiatives that inform biodiversity conservation efforts.
Graphical Abstract
Introduction
To protect species and the ecosystem services which they provide, comprehensive monitoring is critical to understand the trends, risks, and drivers of biodiversity loss (Pimm et al. 2014; Hochkirch et al. 2021). However, biodiversity monitoring in Canada is challenging because of its status as the world’s second-largest nation and the difficulty in accessing remote areas (Archambault et al. 2010). This is particularly true for marine habitats because sampling requires expensive ship support (Archambault et al. 2010). With the world’s longest coastline bordering three oceans and an estimated 71%–91% of marine taxa undescribed (Costello et al. 2010; Mora et al. 2011; Appeltans et al. 2012; Luypaert et al. 2020; Bouchet et al. 2023; Rogers et al. 2023), there are substantial gaps in knowledge of the Canadian marine fauna.
By differentiating species based on standardized DNA regions (Hebert et al. 2003; Hebert et al. 2003), DNA barcoding makes it possible to map species distributions at scale. It not only enables estimates of species diversity, but also aids the recognition of unknown species and tracking biodiversity changes over time (Deiner et al. 2017). DNA barcoding also makes it possible to monitor diversity in lineages whose taxonomy is weakly developed, providing the spatially explicit and taxonomically comprehensive data needed to evaluate changes in species distributions in response to environmental change (Archambault et al. 2010; Hochkirch et al. 2021; Borgelt et al. 2022). Building on the capabilities provided by the Barcode of Life Data System (BOLD) (Ratnasingham and Hebert 2007, 2013), Canada has been the global leader in this approach, significantly advancing the understanding and conservation of its biodiversity. However, gaps in the sequence database hinder scalable, high-resolution biosurveillance (Leray and Knowlton 2016; Sinniger et al. 2016; Weigand et al. 2019).
