Belgian Network for DNA Barcoding

Molecular systematic studies provide biologists, and particularly taxonomists, with a wealth of data that enable a far better assessment and understanding of Earth's biodiversity, than hitherto was possible with traditional, morphology-based approaches. As such, molecular systematics plays a pivotal role in (1) the recognition, identification and classification of taxonomic units, (2) the assessment of patterns of inter- and intraspecific biodiversity, and (3) the reconstruction of the historical and spatial relationships among taxonomic entities. In short: molecular systematics has become a research discipline that is essential to study the evolution of the biodiversity on Earth.

Since the Convention on Biological Diversity, the international community has the ambition to describe the world's biodiversity as soon as possible, e.g. within the next 25 years. This daunting task requires an enormous speed-up in species discovery and description. One of the most promising methods to help achieving this goal is DNA barcoding. With this technique species level taxa are characterized by a short and standard DNA sequence used as a molecular identifier. As such, DNA barcode sequences can be obtained reasonably quick and cheap. The first half of the cytochrome c oxidase subunit I mitochondrial DNA region (COI) is the standard barcode region for animals and the chloroplast matK and rbcL genes for plants. However, there is still much debate on the validity, reliability and universal applicability of these consensus standard barcode regions because of conceptual and practical problems. Among others, frequent hybridisation between taxonomic units, incomplete lineage sorting, nuclear-mitochondrial pseudogenes (numts), cytoplasmic endosymbionts (e.g. Wolbachia), chimeric organisms, and lateral gene transfers (in prokaryotes) may make their use complicated. Moreover, also several technical and/or theoretical issues still need to be addressed, such as the optimal sequence length of DNA barcodes, the number of individuals to be surveyed, the size and reliability of the threshold distinguishing between intra- and interspecific differentiation, the vouchering of (difficult) specimens, the respective species concepts in different lineages of the Tree of Life, and many more. Finally, DNA barcoding as a taxonomic endeavour needs to account for the growing shortage of taxonomists who can provide a biological (e.g. in terms of species concepts) and nomenclatural interpretation of the new taxa uncovered through DNA barcodes (the so-called ‘taxonomic impediment’). All these problems make that molecular taxonomy and DNA barcoding strongly benefit from integrative approaches in which these problems are tackled in an integrated and multidisciplinary way.

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