The arctic biome is a relatively young ecosystem with ∼2300 species of vascular plants. We studied the genus Ranunculus as an example of the origin and evolution of the arctic flora. For this purpose we used molecular phylogenetic and clock analyses based on evaluation of nuclear ITS and chloroplast matK‐trnK DNA sequences in 194 taxa of Ranunculus and closely related genera. Taxa occurring in the Arctic arose from seven phylogenetic lineages of Ranunculus and also in the genera Coptidium and Halerpestes. Two clades of Ranunculus are species‐rich in the Arctic, i.e., Ranunculus sect. Ranunculus and R. sect. Auricomus (both from R. subg. Ranunculus), but this is due to a number of arctic “microtaxa” morphologically barely separate from R. acris in the former clade and the widely agamospermic species complex of R. auricomus in the latter. Lineages with species adapted to wetlands or aquatic habitats are significant groups represented in the arctic flora (R. subg. Ranunculus sectt. Flammula and Hecatonia/Xanthobatrachium, R. subg. Batrachium, genus Coptidium) but show no clear signs of radiation in the Arctic or the northern boreal zone, except for sectt. Hecatonia/Xanthobatrachium, with R. hyperboreus and R. sceleratus subsp. reptabundus. Astonishingly few of the otherwise numerous lineages of Ranunculus with distributions in the higher mountain systems of Eurasia and North America have acted as “founding sources” for the arctic flora. The only clear example is that of the arctic‐alpine R. glacialis and the Beringian R. chamissonis from the lineage of subg. R. sectt. Aconitifolii/Crymodes, although there might be others in sect. Auricomus not recovered in the current molecular data. Lineages that gave rise to arctic taxa diverged from each other from the early Miocene (R. glacialis/R. chamissonis, Coptidium, lineages in Halerpestes) and continued at an even rate throughout the Tertiary. There are no signs that the intense climate changes of the late Pliocene and the Quaternary substantially accelerated or impeded diversification in Ranunculus. Only the crown group split of R. acris and its relatives is clearly of Quaternary age. A detailed comparison concerning morphology, karyology, and life form excludes fundamental differences between taxa of Ranunculus in the Arctic and their respective closest relatives in regions south of it. Ecological traits, e.g., preferences for dry or moist soils or growth in open and sheltered conditions, also do not differ between arctic and nonarctic taxa. Migration into the Arctic thus started from different phylogenetic lineages and at different times, without development of obvious special traits in the adaptation to arctic environments. This recurrent pattern in Ranunculus differs from that seen in other arctic genera, e.g., Artemisia, in which special traits of adaptation to arctic environments are found. In Ranunculus, the origin of the open arctic biome primarily favored range expansions of taxa/species already adapted to wet habitats in cold areas and depending on rapid dispersal.

中文翻译：

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北极植物群的来源：毛茛属和相关属中北极物种的起源

北极生物群落是一个相对年轻的生态系统，拥有约 2300 种维管植物。我们研究毛茛属作为北极植物群起源和进化的一个例子。为此，我们基于对毛茛属和密切相关属的 194 个分类群中核 ITS 和叶绿体 matK-trnK DNA 序列的评估，使用了分子系统发育和时钟分析。出现在北极的分类群来自毛茛属的七个系统发育谱系，也出现在黄芪属和哈勒佩斯特属中。毛茛属的两个分支在北极物种丰富，即毛茛科。毛茛和R. sect。Auricomus（均来自 R. subg. Ranunculus），但这是由于许多北极“微分类群”在形态上几乎与前者进化枝中的 R. acris 和后者中的 R. auricomus 广泛的无精子物种复合体分开。具有适应湿地或水生栖息地的物种的谱系是北极植物群中的重要群体（R. subg. Ranunculus sectt. Flammula and Hecatonia/Xanthobatrachium, R. subg. Batrachium, 属 Coptidium）但在北极没有明显的辐射迹象或北寒带地区，教派除外。Hecatonia/Xanthobatrachium，与 R. hyperboreus 和 R. sceleratus subsp。爬行。令人惊讶的是，分布在欧亚大陆和北美洲高山系统的毛茛属的众多谱系中，很少有作为北极植物群的“创始来源”。唯一明显的例子是来自 subg 谱系的北极-高山 R. glacialis 和白令 R. chamissonis。R. 教派。Aconitifolii/Crymodes，虽然在 sect. Auricomus 在当前的分子数据中没有恢复。产生北极分类群的谱系从早中新世（R. glacialis/R. chamissonis、Coptidium、Halerpestes 的谱系）开始彼此分化，并在整个第三纪以均匀的速度延续。没有迹象表明晚上新世和第四纪的剧烈气候变化大大加速或阻碍了毛茛属植物的多样化。只有 R. acris 及其亲属的冠群分裂明显属于第四纪。对形态、核学和生命形式的详细比较排除了北极毛茛属分类群与其在其以南地区各自最亲近的亲属之间的根本差异。生态特性，例如对干燥或潮湿土壤的偏好或在开放和遮蔽条件下的生长，北极和非北极分类群之间也没有区别。因此，迁徙到北极是从不同的系统谱系和不同时间开始的，在适应北极环境方面没有发展出明显的特殊性状。毛茛属的这种反复出现的模式与其他北极属（例如蒿属）中所见的模式不同，在这些属中发现了适应北极环境的特殊特征。在毛茛属中，开放的北极生物群落的起源主要有利于已经适应寒冷地区潮湿栖息地并依赖于快速扩散的分类群/物种的范围扩展。毛茛属的这种反复出现的模式与其他北极属（例如蒿属）中所见的模式不同，在这些属中发现了适应北极环境的特殊特征。在毛茛属中，开放的北极生物群落的起源主要有利于已经适应寒冷地区潮湿栖息地并依赖于快速扩散的分类群/物种的范围扩展。毛茛属的这种反复出现的模式与其他北极属（例如蒿属）中所见的模式不同，在这些属中发现了适应北极环境的特殊特征。在毛茛属中，开放的北极生物群落的起源主要有利于已经适应寒冷地区潮湿栖息地并依赖于快速扩散的分类群/物种的范围扩展。