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Evolutionary history of two rare endemic conifer species from the eastern Qinghai–Tibet Plateau
Annals of Botany ( IF 4.2 ) Pub Date : 2021-09-02 , DOI: 10.1093/aob/mcab114
Jibin Miao 1, 2 , Perla Farhat 1, 3 , Wentao Wang 1 , Markus Ruhsam 4 , Richard Milne 5 , Heng Yang 1 , Sonam Tso 2 , Jialiang Li 1 , Jingjing Xu 1 , Lars Opgenoorth 6 , Georg Miehe 6 , Kangshan Mao 1, 2
Affiliation  

Background and Aims Understanding the population genetics and evolutionary history of endangered species is urgently needed in an era of accelerated biodiversity loss. This knowledge is most important for regions with high endemism that are ecologically vulnerable, such as the Qinghai–Tibet Plateau (QTP). Methods The genetic variation of 84 juniper trees from six populations of Juniperus microsperma and one population of Juniperus erectopatens, two narrow-endemic junipers from the QTP that are sister to each other, was surveyed using RNA-sequencing data. Coalescent-based analyses were used to test speciation, migration and demographic scenarios. Furthermore, positively selected and climate-associated genes were identified, and the genetic load was assessed for both species. Key Results Analyses of 149 052 single nucleotide polymorphisms showed that the two species are well differentiated and monophyletic. They diverged around the late Pliocene, but interspecific gene flow continued until the Last Glacial Maximum. Demographic reconstruction by Stairway Plot detected two severe bottlenecks for J. microsperma but only one for J. erectopatens. The identified positively selected genes and climate-associated genes revealed habitat adaptation of the two species. Furthermore, although J. microsperma had a much wider geographical distribution than J. erectopatens, the former possesses lower genetic diversity and a higher genetic load than the latter. Conclusions This study sheds light on the evolution of two endemic juniper species from the QTP and their responses to Quaternary climate fluctuations. Our findings emphasize the importance of speciation and demographic history reconstructions in understanding the current distribution pattern and genetic diversity of threatened species in mountainous regions.

中文翻译:

青藏高原东部两种珍稀特有针叶树种的进化史

背景和目标在生物多样性加速丧失的时代,迫切需要了解濒危物种的种群遗传学和进化史。这些知识对于生态脆弱的高特有性地区最为重要,例如青藏高原(QTP)。方法利用RNA测序数据,对来自QTP的两株姐妹小种杜松6个种群和1个直立杜松种群的84棵杜松树进行遗传变异调查。基于聚结的分析用于测试物种形成、迁移和人口统计情景。此外,确定了积极选择的和气候相关的基因,并对这两个物种的遗传负荷进行了评估。主要结果 对 149 052 个单核苷酸多态性的分析表明,这两个物种具有良好的分化和单系性。它们在上新世晚期出现分歧,但种间基因流动一直持续到末次盛冰期。通过 Stairway Plot 进行的人口统计重建检测到 J. microsperma 的两个严重瓶颈,但 J. erectopatens 只有一个瓶颈。确定的阳性选择基因和气候相关基因揭示了这两个物种的栖息地适应。此外,虽然 J. microsperma 的地理分布比 J. erectopatens 更广泛,但前者的遗传多样性较低,遗传负荷高于后者。结论 本研究揭示了青藏高原两种地方性杜松物种的进化及其对第四纪气候波动的反应。
更新日期:2021-09-02
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