Graduate School of Human and Environmental Studies, Kyoto University, Kyoto, 606-8501, Japan.
Faculty of Integrated Human Studies, Kyoto University, Kyoto, 606-8501, Japan.
Heredity (Edinb). 2021 Apr;126(4):615-629. doi: 10.1038/s41437-020-00396-4. Epub 2021 Jan 28.
Climate relicts hold considerable importance because they have resulted from numerous historical changes. However, there are major interspecific variations among the ways by which they survived climate changes. Therefore, investigating the factors and timing that affected population demographics can expand our understanding of how climate relicts responded to historical environmental changes. Here, we examined herbaceous hydrangeas of genus Deinanthe in East Asia, which show limited distributions and a remarkable disjunction between Japan and central China. Chloroplast genome and restriction site-associated DNA sequencing revealed that speciation event occurred in the late Miocene (ca. 7-9 Mya) in response to global climate change. Two lineages apparently remained not branched until the middle Quaternary, and afterwards started to diverge to regional population groups. The narrow endemic species in central China showed lower genetic diversity (He = 0.082), as its population size rapidly decreased during the Holocene due to isolation in montane refugia. Insular populations in the three Japanese islands (He = 0.137-0.160) showed a genetic structure that was inconsistent with sea barriers, indicating that it was shaped in the glacial period when its range retreated to coastal refugia on the exposed sea floor. Demographic modelling by stairway-plot analysis reconstructed variable responses of Japanese populations: some experienced glacial bottlenecks in refugial isolation, while post-glacial range expansion seemingly exerted founder effects on other populations. Overall, this study demonstrated the involvement of not just one, but multiple factors, such as the interplay between climate changes, geography, and other population-specific factors, that determine the demographics of climate relicts.
气候遗留种具有重要意义，因为它们是历史变化的结果。然而，它们在应对气候变化的方式上存在很大的种间差异。因此，研究影响种群动态的因素和时间可以帮助我们更好地理解气候遗留种是如何应对历史环境变化的。在这里，我们研究了东亚的草本绣球属（Deinanthe）植物，它们的分布范围有限，在日本和中国中部之间存在显著的间断。叶绿体基因组和限制性位点相关 DNA 测序表明，物种形成事件发生在中新世晚期（约 7-9 百万年前），是对全球气候变化的响应。两个谱系显然在第四纪中期之前没有分支，之后开始向区域性种群分化。中国中部狭窄的特有种表现出较低的遗传多样性（He=0.082），因为其种群数量在全新世期间由于山地避难所的隔离而迅速减少。三个日本岛屿上的岛屿种群（He=0.137-0.160）表现出与海障不一致的遗传结构，表明这是在冰川期形成的，当时其分布范围退缩到暴露的海底沿海避难所。阶梯图分析的种群动态模拟重建了日本种群的可变响应：一些种群在避难所隔离中经历了冰川瓶颈，而冰后期的范围扩张似乎对其他种群产生了奠基者效应。总体而言，这项研究表明，不仅有一个因素，而是多个因素，如气候变化、地理和其他种群特定因素的相互作用，决定了气候遗留种的种群动态。
