Tibetan Plateau imposes extremely inhospitable environment on most wildlife. Besides the harsh aquatic environment including hypoxia and chronic cold, high salinity and alkalinity is an increasing threat to Tibetan endemic fishes. Previous genome-wide studies identified key genes contributed to highland fish adaptation to hypoxia and long-term cold, while our understanding of saline and alkaline adaptation in Tibetan fish remains limited. In this study, we performed a comparative genomics analysis in a saline lake-dwelling highland fish Gymnocypris przewalskii, aimed to identify candidate genes that contributed to saline and alkaline adaptation. We found elevated genome-wide rate of molecular evolution in G. przewalskii relative to lowland teleost fish species. In addition, we found nine genes encoding biological macromolecules associated with ion transport functions underwent accelerated evolution in G. przewalskii, which broadly expressed across kidney, gill, liver, spleen, brain and muscle tissues. Moreover, we found putative evidence of ion transport under selection was interacted by co-expression in G. przewalskii adaptation to high salinity and alkalinity environment of Lake Qinghai. Taken together, our comparative genomics study identified a set of rapidly evolving ion transport genes and transcriptomic signatures in Schizothoracine fish adaptation to saline and alkaline environment on the Tibetan Plateau.

青藏高原给大多数野生生物带来了极其荒凉的环境。除了低氧和慢性寒冷等恶劣的水生环境外，高盐度和碱度对藏族特有鱼类的威胁也越来越大。先前的全基因组研究确定了关键基因有助于高原鱼类适应缺氧和长期感冒，而我们对藏族鱼类盐分和碱性适应的了解仍然有限。在这项研究中，我们在居住在盐湖中的高地鱼类Gymnocypris przewalskii中进行了比较基因组学分析，旨在鉴定有助于盐和碱适应的候选基因。我们发现G. przewalskii的全基因组分子进化速率升高相对于低地硬骨鱼类种类。此外，我们发现9个编码与离子转运功能相关的生物大分子的基因在G. przewalskii中经历了加速的进化，而该基因在肾脏，腮，肝脏，脾脏，大脑和肌肉组织中广泛表达。此外，我们发现，在选择离子传输的假定证据由在共同表达相互作用G.圆柏适应高盐度和青海湖的碱性环境。综上所述，我们的比较基因组学研究确定了裂殖壶鱼鱼类适应青藏高原盐碱环境的一组快速发展的离子转运基因和转录组特征。