Department of Plant Biology, University of Illinois, Urbana, IL 61801, USA.
Mol Phylogenet Evol. 2012 Sep;64(3):471-90. doi: 10.1016/j.ympev.2012.05.003. Epub 2012 May 11.
Artemisia is the largest genus (ca. 350-500+ spp.) in the tribe Anthemideae and is composed of ecologically, morphologically, and chemically diverse species that are found primarily throughout the Northern Hemisphere. Two major centers of diversity for the genus are located in Eurasia and western North America, but phytogeographic links connecting these two regions are observed all across the North Pacific Rim and adjacent areas in the Arctic, including many islands and archipelagos. Previous phylogenetic studies have helped to clarify major lineages and identify likely sister relationships, but many questions remain unanswered regarding the relationships and migration history of New and Old World species. Here we investigate the phylogenetics of Artemisia within a biogeographic context centered in the Beringian Region and offer new hypotheses concerning species relationships, migration history, and the likely role of reticulate evolution in the genus. Our sampling included many new taxa and emphasized multiple accessions of widespread species, species from proposed refugia, and species with disjunct/vicariant distributions. The ITS phylogeny contained 173 accessions (94 new and 79 from GenBank) and indicated that Artemisia is paraphyletic by the exclusion of several small Asian genera and the North American genus Sphaeromeria. Following a survey of thirteen chloroplast loci, phylogenies based on two plastid markers (psbA-trnH and rpl32-trnL spacers) were constructed with a reduced data set, and though largely consistent with the ITS topology, revealed several cases of possible introgression among New World and Beringian species. Our analysis reveals that North American Artemisia species have multiple origins, and that western North America has served as a source for some colonizing elements in eastern Asia and South America.
蒿属（Artemisia）是春黄菊族（Anthemideae）中最大的属（约 350-500+种），由生态、形态和化学多样性的物种组成，主要分布于北半球。该属的两个主要多样性中心位于欧亚大陆和北美西部，但在北太平洋沿岸及其北极地区的相邻地区观察到连接这两个地区的植物地理联系，包括许多岛屿和群岛。先前的系统发育研究有助于阐明主要谱系并确定可能的姐妹关系，但关于新旧世界物种的关系和迁移历史仍有许多问题尚未得到解答。在这里，我们在以白令地区为中心的生物地理背景下研究了蒿属的系统发育，并提出了有关物种关系、迁移历史以及物种形成在该属中的可能作用的新假设。我们的采样包括许多新的分类群，并强调了广泛分布物种的多个样本、来自提议避难所的物种以及具有间断/分化分布的物种。ITS 系统发育树包含 173 个样本（94 个新样本和 79 个来自 GenBank），表明蒿属由于排除了几个亚洲小属和北美属 Sphaeromeria 而成为并系群。在对 13 个叶绿体基因座进行调查后，根据两个质体标记（psbA-trnH 和 rpl32-trnL 间隔区）构建了系统发育树，用一个简化数据集，尽管与 ITS 拓扑基本一致，但揭示了一些新的可能在新世界和白令地区物种之间发生基因渗透的情况。我们的分析表明，北美蒿属物种具有多个起源，并且北美西部是一些在东亚和南美洲进行殖民的元素的来源。
