Abstract

We present the first national DNA barcode resource for Wales that includes native conifers and blooming plants (1143 species). We have assembled 97.7% coverage for rbcL, 90.2% coverage for matK, and a dual-locus barcode for 89.7% of the native Welsh flora using the plant DNA barcode markers rbcL and matK. For each species, weM sampled several individuals, yielding 3304 rbcL and 2419 matK sequences. 85% of our samples come from DNA that was taken from herbarium specimens. Herbarium specimens exhibit lower DNA barcode recoverability than recently obtained material, mostly because of lower amplification success. However, this is offset by the greater sampling effectiveness of species that have already been gathered, identified, and certified by taxonomists. Four methods are used to evaluate the usefulness of DNA barcodes for identification (degree of discrimination), including pairwise and multiple alignments, Neighbour-Joining trees, sequence similarity in BLASTn searches, and the presence of a barcode gap [1]. These methods produce comparable outcomes, with relative discrimination values of 98.6 to 99.8% of genera and 69.4 to 74.9% of all species utilising both markers. Spatially explicit sampling can further enhance species discrimination. Within 1010 km squares, the mean species discrimination using barcode gap analysis (with a multiple alignment) is 81.6%, and within 22 km squares, it is 93.3%. Our library of DNA barcodes for native Welsh conifers and flowering plants gives the most thorough coverage of any national flora and provides a useful framework for a variety of applications that call for precise species identification.