Abstract：
Abyssal (3501-6500 m) and hadal (>6500 m) fauna evolve under harsh abiotic stresses, characterized by high hydrostatic pressure, darkness and food shortage, providing unique opportunities to investigate mechanisms underlying environmental adaptation. Genomes of several hadal species have recently been reported. However, the genetic adaptation of deep sea species across a broad spectrum of ocean depths has yet to be thoroughly investigated, due to the challenges imposed by collecting the deep sea species. To elucidate the correlation between genetic innovation and vertical distribution, we generated a chromosome-level genome assembly of the macrourids Coryphaenoides yaquinae, which is widely distributed in the abyssal/hadal zone ranging from 3655 to 7259 m in depth. Genomic comparisons among shallow, abyssal and hadal-living species identified idiosyncratic and convergent genetic alterations underlying the extraordinary adaptations of deep-sea species including light perception, circadian regulation, hydrostatic pressure and hunger tolerance. The deep-sea fishes (Coryphaenoides Sp. and Pseudoliparis swirei) venturing into various ocean depths independently have undergone convergent amino acid substitutions in multiple proteins such as rhodopsin 1, pancreatic and duodenal homeobox 1 and melanocortin 4 receptor which are known or verified in zebrafish to be related with vision adaptation and energy expenditure. Convergent evolution events were also identified in heat shock protein 90 beta family member 1 and valosin-containing protein genes known to be related to hydrostatic pressure adaptation specifically in fishes found around the hadal range. The uncovering of the molecular convergence among the deep-sea species shed new light on the common genetic innovations required for deep-sea adaptation by the fishes.
摘要：
深渊（3501-6500m）和强达（>6500m）动物区系在恶劣的非生物胁迫下进化，具有高静水压力的特点，黑暗和食物短缺，提供独特的机会来调查潜在的环境适应机制。最近已经报道了几种hadal物种的基因组。然而,深海物种在广泛海洋深处的遗传适应性尚未得到彻底研究，由于收集深海物种带来的挑战。为了阐明遗传创新与垂直分布之间的相关性，我们产生了一个染色体水平的基因组组装体，广泛分布在深3655~7259m的深海/hadal带。浅层之间的基因组比较，深海和有生命的物种确定了特殊和趋同的遗传改变，这些改变是深海物种异常适应的基础，包括光感知，昼夜节律调节，静水压力和饥饿的耐受性。深海鱼类（CoryphaenoidesSp。和Pseudoliparisswirei）独立地冒险进入不同的海洋深度，在多种蛋白质中经历了趋同的氨基酸取代，例如视紫红质1，胰腺和十二指肠同源盒1以及黑皮质素4受体，这些蛋白质在斑马鱼中已知或证实与视觉适应和能量消耗有关。在热休克蛋白90β家族成员1和含谷蛋白酶的蛋白质基因中也发现了趋同进化事件，这些基因已知与静水压力适应有关，特别是在hadal范围内的鱼类中。深海物种之间分子趋同的发现为鱼类深海适应所需的共同遗传创新提供了新的思路。
