School of Ecology and Environment, Northwestern Polytechnical University, Xi'an, China
Honghui Zeng
Key Laboratory of Aquatic Biodiversity and Conservation, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
Xiaoni Gan
Key Laboratory of Aquatic Biodiversity and Conservation, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
Chenguang Feng
School of Ecology and Environment, Northwestern Polytechnical University, Xi'an, China
Jiangmin Zheng
School of Ecology and Environment, Northwestern Polytechnical University, Xi'an, China
Jing Bo
Institute of Deep-Sea Science and Engineering, Chinese Academy of Sciences, Sanya, China
Li-Sheng He
Institute of Deep-Sea Science and Engineering, Chinese Academy of Sciences, Sanya, China
Qiang Qiu
School of Ecology and Environment, Northwestern Polytechnical University, Xi'an, China
Wen Wang
School of Ecology and Environment, Northwestern Polytechnical University, Xi'an, China
Shunping He
School of Ecology and Environment, Northwestern Polytechnical University, Xi'an, China; Institute of Deep-Sea Science and Engineering, Chinese Academy of Sciences, Sanya, China; Key Laboratory of Aquatic Biodiversity and Conservation, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
As the deepest vertebrate in the ocean, the hadal snailfish (Pseudoliparis swirei), which lives at a depth of 6,000–8,000 m, is a representative case for studying adaptation to extreme environments. Despite some preliminary studies on this species in recent years, including their loss of pigmentation, visual and skeletal calcification genes, and the role of trimethylamine N-oxide in adaptation to high-hydrostatic pressure, it is still unknown how they evolved and why they are among the few vertebrate species that have successfully adapted to the deep-sea environment. Using genomic data from different trenches, we found that the hadal snailfish may have entered and fully adapted to such extreme environments only in the last few million years. Meanwhile, phylogenetic relationships show that they spread into different trenches in the Pacific Ocean within a million years. Comparative genomic analysis has also revealed that the genes associated with perception, circadian rhythms, and metabolism have been extensively modified in the hadal snailfish to adapt to its unique environment. More importantly, the tandem duplication of a gene encoding ferritin significantly increased their tolerance to reactive oxygen species, which may be one of the important factors in their adaptation to high-hydrostatic pressure.
