Application of DNA barcodes for the discovery of marine animal diversity.

Abstract

DNA barcoding is a useful tool for the correct identification of species. The most commonly usedsequence is a 350 to 800 bp-long fragment of the mitochondrial gene Cytochrome Oxidase I (COI). This fragment has been successfully used to identify cryptic species and has contributed to an increased understanding of animal diversity. However, its use in plants and fungi has been unsuccessful and results have been inconsistent when used in other groups such as marine sponges. This work analyses current data available in the BOLD System V3 database. It compares how the BOLD system has evolved and complements this with an analysis of current literature. This analysis reveals several important facts, among which is the notable increase in sequences submitted between 2009 and 2013 and an increase in the rate of sequence submission since 2013. The analysis also reveals a clear bias in the phyla that are being sequenced for barcoding. Of the 52525 species of marine molluscs only 9.2% have their barcode available. This percentage is even lower (7.6%) for arthropods. This contrasts with marine chordates in which 33.6% of the 21515 known species have their barcodes available. This data suggests a bias towards charismatic and commercially important species. Finally, the general analysis of BOLD database reveals 70% ofbarcodes are assigned to clearly identified species and near 30% to interim species (those for which a name cannot be definitively assigned to), which highlights the inaccuracies of the identification system.