THE GOOD, THE BAD AND THE UGLY: INSIGHTS FROM ODONATA BARCODING
Sónia Ferreira (CIBIO-InBIO, Portugal) | November 22nd, 2017 | 7th International Barcode of Life Conference, Kruger National Park, South Africa
DNA barcoding is currently an essential tool in a vast array of ecological and conservation studies (e.g. biodiversity monitoring, diet assessments). However, its applicability is still hampered by the lack of comprehensive reference collections. This knowledge gap becomes greater in invertebrates, especially from biodiversity hotspots like the Mediterranean Basin. Surprisingly, while dragonflies and damselflies are one of the best studied insect groups, no comprehensive barcoding of the European species has been made. These predatory insects are intimately connected to freshwater habitats, as their larval phase is completed in the water, being particularly sensitive to changes in the aquatic environment and constituting important bioindicators of ecosystem health.
Within InBIO Barcoding Initiative we barcoded more than 70 species of odonates, focusing mostly on species from Iberian Peninsula. Genomic DNA was extracted and the barcoding mitochondrial COI gene fragment (658 bp) was amplified. DNA barcodes were sequenced using either Sanger or high-throughput sequencing (Illumina).
Our results exhibited a scenario that illustrates some of the challenges posed by insect identification using DNA barcoding. While many species can be easily identified using the mitochondrial COI gene fragment, this is not truth to all. Not all species possess a specific DNA barcode that allows the correct assignment of taxonomic names to unidentified specimens. For instance, two groups of Coenagrionids species share mtDNA haplotypes. Other species possess multiple copies of COI in the genome, impeding successful Sanger sequencing, which can be overcome using Next Generation Sequencing. These sequences are also likely to be detected in eDNA metabarcoding studies, and should therefore be documented and databased for more accurate estimation of taxa diversity and species identification. This data provides important insights into the diversity and taxonomy of odonates and guidelines to achieve a more reliable and useful Barcode reference database.