The enormous repetitive Antarctic krill genome reveals environmental adaptations and population insights

Chunli Shao ,Jiang Hu,He Zhang,Inge Seim,Guangyi Fan,Kailong Ma,Shanshan Liu,Xin Liu,Shuai Sun,Bettina Meyer,Alberto Biscontin,Yue Wang,Cristiano De Pittà,Kaiqiang Liu,Qian Wang,Bo Feng,Simon Jarman,Jiahao Wang,Jiancheng Zhu,Yalin Liu,Xinliang Wang,Tao Sun,Jue Ruan,Yaolei Zhang,Jiakun Xu,Bruce E Deagle,Rui Wang,Jun Wang,Shanshan Pan,Guojie Zhang,Xun Xu,Mengyang Xu,Shuo Li,Bowen Yue,Shufang Liu,Huanming Yang,Yiping Ying,Xiaodong Jia,Yuyan Liu,Xiancai Hao,Guodong Huang,So Kawaguchi,Yan Wang ,Qun Li ,Gabrielle Bezerra Sales ,Yi‐Fang Zhao ,Xiaolan Zhao ,Yijing Sun ,Hongyan Wang

doi:10.1016/j.cell.2023.02.005

Abstract

Antarctic krill (Euphausia superba) is Earth's most abundant wild animal, and its enormous biomass is vital to the Southern Ocean ecosystem. Here, we report a 48.01-Gb chromosome-level Antarctic krill genome, whose large genome size appears to have resulted from inter-genic transposable element expansions. Our assembly reveals the molecular architecture of the Antarctic krill circadian clock and uncovers expanded gene families associated with molting and energy metabolism, providing insights into adaptations to the cold and highly seasonal Antarctic environment. Population-level genome re-sequencing from four geographical sites around the Antarctic continent reveals no clear population structure but highlights natural selection associated with environmental variables. An apparent drastic reduction in krill population size 10 mya and a subsequent rebound 100 thousand years ago coincides with climate change events. Our findings uncover the genomic basis of Antarctic krill adaptations to the Southern Ocean and provide valuable resources for future Antarctic research.

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