Ophiuroid phylogenomics: Illuminating “dark” abyssal biodiversity

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The abyssal plains represent perhaps the single largest contiguous ecosystem and it is believed to be major reservoirs of biodiversity. Large areas of abyssal plains are known to have economically important concentrations of polymetallic nodules, while the largest and commercially important reservoir of nodules occurs in the Clarion-Clipperton Zone (CCZ). Future deep-sea mining of this resource will inevitably impact one of the most remote and least known environments on Earth and result in massive habitat loss and probably species extinctions. Ophiuroids (brittle stars) are amongst the most conspicuous mega-faunal invertebrates on these abyssal plain. Because of the biological variation expressed within the order, ophiuroids provide an excellent model for studying evolutionary hypotheses in unique environments such as the abyssal plains and disentangle processes that shape the distribution of biodiversity. Even more so, as a recent study of us, resulted in the discovery of three hitherto unknown, ancient (>70 Mya) multi-taxon lineages of uncertain origin. The project aims to infer the evolutionary history of Ophiuroidea and uncover the "dark" (undescribed) biodiversity in the abyssal deep-sea. For this reason a comprehensive study by combining traditional (first-generation Sanger sequencing, morphology) and innovative approaches (Next Generation transcriptome-enabled exon capture) will be employed. Museum and newly collected specimens will be identified after morphological examination for which the use of Scanning Electron Microscope will allow finer scale analysis. First-generation Sanger sequencing will be applied in order to obtain DNA sequence data of 2 markers with different attributes that will provide an essential resource for the identification of species, as well as complement existing DNA barcode reference libraries. Furthermore, a cutting edge next-generation process will be employed to target and sequence over 1500 exons. The large multi-locus dataset produced will allow the reconstruction of a robust, well resolved, phylogenetic framework necessary for describing the evolutionary history of deep-sea brittle stars by inferring a highly resolved molecular phylogeny and estimating divergence dates between major lineages. Using a multidisciplinary taxonomical approach (molecular, morphological, distributional data), species boundaries will be determined and new species described.