Genome and population evolution and environmental adaptation of <i>Glyptosternon maculatum</i> on the Qinghai-Tibet Plateau
Shijun Xiao, 西藏自治区农牧科学院水产科学研究所，西藏 拉萨 81000，中国, Zen-Bo Mou, Ruibin Yang, Dingding Fan, Jiaqi Liu, Yu Zou, Shilin Zhu, Ming Zou, Chaowei Zhou, Haiping Liu, 武汉理工大学计算机科学与技术学院，湖北 武汉 430070，中国, 华中农业大学水产学院，湖北 武汉 430070，中国, 西南大学水产学院淡水鱼类资源与生殖发育教育部重点实验室（教育部），重庆 402400，中国, 吉林农业大学植物保护学院，吉林 长春 130118，中国, 嘉兴市经济菌物新种质资源创制重点实验室，浙江 嘉兴 314000，中国
Abstract
Persistent uplift means the Qinghai-Tibet Plateau (QTP) is an ideal natural laboratory to investigate genome evolution and adaptation within highland environments. However, how paleogeographic and paleoclimatic events influence the genome and population of endemic fish species remains unclear. <i>Glyptosternon maculatum</i> is an ancient endemic fish found on the QTP and the only critically endangered species in the Sisoridae family. Here, we found that major transposons in the <i>G. maculatum</i> genome showed episodic bursts, consistent with contemporaneous geological and climatic events during the QTP formation. Notably, histone genes showed significant expansion in the <i>G. maculatum</i> genome, which may be mediated by long interspersed nuclear elements (LINE) repetitive element duplications. Population analysis showed that ancestral <i>G. maculatum</i> populations experienced two significant depressions 2.6 million years ago (Mya) and 10 000 years ago, exhibiting excellent synchronization with Quaternary glaciation and the Younger Dryas, respectively. Thus, we propose that paleogeography and paleoclimate were dominating driving forces for population dynamics in endemic fish on the QTP. Tectonic movements and temperature fluctuation likely destroyed the habitat and disrupted the drainage connectivity among populations. These factors may have caused severe bottlenecks and limited migration among ancestral <i>G. maculatum</i> populations, resulting in the low genetic diversity and endangered status of the species today.