Historical climate oscillations and tectonic events have influenced the speciation and evolutionary history of many organisms. In this study, we chose Fokienia hodginsii (Dunn) A. Henry & H. H. Thomas (Cupressaceae s.l.), a Tertiary relict conifer, for the inference of the demographic history since the Neogene. Five chloroplast regions and two single-copy nuclear genes were amplified and sequenced in 497 individuals from 28 populations. The chloroplast data showed that F. hodginsii presented a high level of genetic diversity (H _T  = 0.860 ± 0.0279) and significant phylogeographic structure (N _ST  > G _ST , P < 0.05). According tobeast analysis, the divergence time of the two major lineages indicated by the phylogenetic construction produced from chloroplast and nuclear data could be dated to the early Miocene (ca. 19.34–19.95 Ma), which coincided with the onset and intensification of the Asian monsoon. During this time, environmental adaption under the different climatic conditions on either side of the Tanaka Line could have played important roles in maintaining and/or reinforcing the divergence of the two major lineages. The ecological niche modeling results showed that F. hodginsii experienced habitat fragmentation and strengthening of genetic barriers during the Last Glacial Maximum, followed by local expansion during postglacial periods. Our findings show that paleoclimate changes since the Neogene might have triggered the extinction of all but one Fokienia species and its intraspecific lineage differentiation. This study also suggests that Tertiary relicts in subtropical and tropical areas might have had a complex evolutionary history and their intraspecific differentiation time might have been earlier than expected.

中文翻译：

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新近纪和第四纪气候变化塑造了东亚第三纪遗存福建柏（柏科 sl）的谱系分化和人口历史

历史气候振荡和构造事件影响了许多生物的物种形成和进化史。在本研究中，我们选择了第三纪残余针叶树Fokienia hodginsii (Dunn) A. Henry & HH Thomas (Cupressaceae sl) 来推断新近纪以来的人口统计历史。在来自 28 个种群的 497 个个体中扩增和测序了五个叶绿体区域和两个单拷贝核基因。叶绿体数据显示F. hodginsii呈现高水平的遗传多样性 ( H _T  = 0.860 ± 0.0279) 和显着的系统地理学结构 ( N _ST  >  G _ST , P  < 0.05)。根据兽 分析表明，由叶绿体和核数据产生的系统发育构建表明的两个主要谱系的分歧时间可以追溯到中新世早期（约 19.34-19.95 Ma），这与亚洲季风的开始和加强相吻合。在此期间，田中线两侧不同气候条件下的环境适应可能在维持和/或加强两大世系的分化方面发挥了重要作用。生态位建模结果表明F. hodginsii在末次盛冰期经历了栖息地破碎和遗传障碍的加强，随后在冰后时期局部扩张。我们的研究结果表明，自新近纪以来的古气候变化可能引发了除一种Fokienia物种及其种内谱系分化之外的所有物种的灭绝。这项研究还表明，亚热带和热带地区的第三纪遗迹可能具有复杂的进化历史，它们的种内分化时间可能比预期的要早。