Ophiuroid phylogenomics: Illuminating “dark” abyssal biodiversity

深海平原可能是最大的毗连生态系统，据信是生物多样性的主要储藏地。众所周知，大面积深海平原集中了具有重要经济意义的多金属结核，而最大和具有重要商业意义的结核储层位于克拉里昂-克利珀顿区。未来对这种资源的深海开采将不可避免地影响地球上最偏远和最不为人所知的环境之一，并导致大规模的栖息地丧失和可能的物种灭绝。蛇类（蛇尾）是这些深海平原上最引人注目的大型动物群无脊椎动物之一。由于在该目中表达的生物变异，蛇类为研究独特环境中的进化假说提供了一个很好的模型，例如深海平原和塑造生物多样性分布的解开过程。更重要的是，作为最近的一项研究，我们发现了三个迄今未知的，古老的（>70 Mya）起源不明的多分类单元谱系。该项目旨在推断蛇类的进化历史，并揭示深海中的“黑暗”（未描述的）生物多样性。因此，将采用传统（第一代桑格测序、形态学）和创新方法（下一代转录组激活的外显子捕获）相结合的综合研究。博物馆和新收集的标本将在形态学检查后进行鉴定，使用扫描电子显微镜进行更精细的分析。将应用第一代桑格测序，以获得具有不同属性的2个标记物的DNA序列数据，这将为种属鉴定提供必要的资源，并补充现有的DNA条形码参考文库。此外，将采用尖端的下一代工艺来靶向和测序超过1500个外显子。产生的大型多位点数据集将允许重建一个强大的，良好的解决，系统发育框架所需的描述深海脆性恒星的进化历史，推断一个高分辨率的分子系统发育和估计主要谱系之间的分歧日期。利用多学科分类方法（分子、形态、分布数据），将确定物种边界并描述新物种。

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.