Ophiuroid phylogenomics: Illuminating “dark” abyssal biodiversity

深海平原可能是单一最大的连续生态系统，它被认为是生物多样性的主要储存库。已知深海平原的大片地区有具有重要经济意义的多金属结核集中，而最大和具有重要商业意义的结核储层位于克拉里昂-克利珀顿带（CCZ）。未来深海开采这种资源将不可避免地影响地球上最偏远、最不为人所知的环境之一，并导致大规模的栖息地丧失，甚至可能导致物种灭绝。蛇尾类（海蛇尾）是这些深海平原上最显眼的大型无脊椎动物之一。由于在目内表达的生物变异，蛇蛉虫为研究独特环境（如深海平原）的进化假设和形成生物多样性分布的解结过程提供了一个极好的模型。更重要的是，最近一项对人类的研究发现了三个迄今为止未知的、起源不明的古代（距今70万年前）多分类群谱系。该项目旨在推断蛇科的进化史，并揭示深海中“黑暗”（未描述的）生物多样性。因此，将采用传统的（第一代Sanger测序，形态学）和创新的方法（下一代转录组激活外显子捕获）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可以进行更精细的规模分析。第一代Sanger测序将用于获得2个不同属性标记的DNA序列数据，为物种鉴定提供重要的资源，并补充现有的DNA条形码参考文库。此外，一个尖端的下一代过程将被用来定位和测序超过1500个外显子。通过推断高度确定的分子系统发育和估计主要谱系之间的分化日期，所产生的大型多位点数据集将允许重建一个强大的、分辨率很高的系统发育框架，这对于描述深海海蛇尾的进化史是必要的。利用多学科分类学方法（分子、形态、分布数据），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.