The eastern Asian (EA)–eastern North American (ENA) floristic disjunction represents a major pattern of phytogeography of the Northern Hemisphere. Despite 20 years of studies dedicated to identification of taxa that display this disjunct pattern, its origin and evolution remain an open question, especially regarding post‐isolation evolution. The blue‐ or white‐fruited dogwoods (BW) are the most species‐rich among the four major clades of Cornus L., consisting of ~35 species divided into three subgenera (subg. Yinquania, subg. Mesomora, and subg. Kraniopsis). The BW group provides an excellent example of the EA–ENA floristic disjunction for biogeographic study due to its diversity distribution centered in eastern Asia and eastern North America, yet its species relationships and delineation have remained poorly understood. In this study, we combined genome‐wide markers from RAD‐seq, morphology, fossils, and climate data to understand species relationships, biogeographic history, and ecological niche and morphological evolution. Our phylogenomic analyses with RAxML and MrBayes recovered a strongly supported and well‐resolved phylogeny of the BW group with three intercontinental disjunct clades in EA and ENA or Eurasia and North America, of which two are newly identified within subg. Kraniopsis. These analyses also recovered a potential new species but failed to resolve relationships within the C. hemsleyi–C. schindleri complex. In an effort to develop an approach to reduce computation time, analysis of different nodal age settings in treePL suggests setting a node's minimum age constraint to the lower bound of a fossil's age range to obtain similar ages to that of BEAST. Divergence time analyses with BEAST and treePL dated the BW stem back to the very Late Cretaceous and the divergence of the three subgenera in the Paleogene. By integrating fossil ages and morphology, a total evidence‐based dating approach was used in conjunction with time‐slice probabilities of dispersal under a DEC model to resolve ancestral ranges of each disjunct in the Miocene: Eurasia and ENA (disjunct 1), EA and western North America (disjunct 2), and EA (disjunct 3). The dated biogeographic history supports dispersal via the North Atlantic Land Bridge in the late Paleogene in disjunct 1 and dispersal via the Bering Land Bridge in the Miocene for disjuncts 2 and 3. Character mapping with a stochastic model in phytools and comparison of ecological niche, morphospace, and rate of evolution indicated differential divergence patterns in morphology, ecological niche, and molecules between disjunct sisters. Although morphological stasis was observed in most of the characters, evolutionary changes in growth habit and some features of leaf, flower, and fruit morphology occurred in one or both sister clades. A significant differentiation of ecological habitats in temperature, precipitation, and elevation between disjunct sisters was observed, suggesting a role of niche divergence in morphological evolution post‐isolation. The patterns of evolutionary rate between morphology and molecules varied among disjunct clades and were not always congruent between morphology and molecules, suggesting cases of non‐neutral morphological evolution driven by ecological selection. Our phylogenetic evidence and comparisons of evolutionary rate among disjunct lineages lend new insights into the formation of the diversity anomaly between EA and ENA, with particular support of an early diversification in EA. These findings, in conjunction with previous studies, again suggest that the EA–ENA disjunct floras are an assembly of lineages descended from the Mesophytic Forests that evolved from the early Paleogene “boreotropical flora” through varied evolutionary pathways across lineages.

中文翻译：

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蓝或白果山茱萸（山茱萸）的系统基因组学、生物地理学和进化——对洲际地理隔离后形态和生态位差异的见解

东亚 (EA)-北美东部 (ENA) 植物区系分离代表了北半球植物地理学的主要模式。尽管有 20 年的研究致力于鉴定显示这种分离模式的分类群，但其起源和进化仍然是一个悬而未决的问题，尤其是在隔离后的进化方面。蓝或白果山茱萸 (BW) 是山茱萸的四个主要进化枝中物种最丰富的，由约 35 个物种组成，分为三个亚属（亚属银泉亚属、亚克系中藻属和亚属金丝藻属） . BW 组为生物地理学研究提供了 EA-ENA 区系分离的一个很好的例子，因为它的多样性分布以东亚和北美东部为中心，但其物种关系和描述仍然知之甚少。在这项研究中，我们结合了来自 RAD-seq、形态学、化石和气候数据的全基因组标记，以了解物种关系、生物地理历史、生态位和形态进化。我们使用 RAxML 和 MrBayes 进行的系统发育分析恢复了 BW 组的系统发育，该组具有 EA 和 ENA 或欧亚大陆和北美的三个洲际分离进化枝，其中两个是在 subg 中新发现的。萝卜。这些分析还发现了一个潜在的新物种，但未能解决 C. hemsleyi-C. 内部的关系。辛德勒情结。为了开发一种减少计算时间的方法，对 treePL 中不同节点年龄设置的分析建议将节点的最小年龄约束设​​置为化石年龄范围的下限，以获得与 BEAST 相似的年龄。使用 BEAST 和 treePL 进行的发散时间分析将 BW 茎追溯到白垩纪晚期和古近纪三个亚属的发散。通过整合化石年龄和形态，在 DEC 模型下结合时间片分布概率，使用基于证据的总测年方法来解析中新世中每个分离区的祖先范围：欧亚大陆和 ENA（分离区 1）、EA 和北美西部（分离 2）和 EA（分离 3）。过时的生物地理历史支持通过古近纪晚期的北大西洋陆桥在分离区 1 中进行扩散，在分离区 2 和 3 中通过中新世的白令陆桥进行扩散。 使用植物工具中的随机模型进行特征映射以及生态位、形态空间的比较, 和进化速度表明分离姐妹之间在形态、生态位和分子方面的差异差异模式。尽管在大多数性状中观察到形态停滞，但在一个或两个姐妹进化枝中发生了生长习性和叶、花和果实形态的一些特征的进化变化。观察到分离姐妹之间生态栖息地在温度、降水和海拔方面的显着差异，表明生态位差异在隔离后的形态演化中发挥了作用。形态和分子之间的进化速率模式在分离的进化枝中各不相同，并且形态和分子之间并不总是一致的，这表明生态选择驱动的非中性形态进化的情况。我们的系统发育证据和分离谱系之间进化速率的比较为 EA 和 ENA 之间多样性异常的形成提供了新的见解，特别支持 EA 的早期多样化。这些发现与之前的研究相结合，再次表明 EA-ENA 分离的植物群是来自中生森林的谱系集合，这些谱系是从古近纪早期“寒带热带植物群”通过跨谱系的不同进化途径进化而来的。