Molecular systematics and historical biogeography of Maianthemum s.s.
Molecular systematics and historical biogeography of Maianthemum s.s.
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DOI：
10.3732/ajb.1600454
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发表时间：
2017-06-01
影响因子：
3
通讯作者：
Kim, Joo-Hwan
中科院分区：
文献类型：
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作者：
Kim, Changkyun;Cameron, Kenneth M.;Kim, Joo-Hwan
研究前提：了解洲际分离模式进化的潜在机制一直吸引着植物学家。本文以分布于欧亚大陆和北美之间的菊属植物为研究对象，对其分子系统发育进行了重建。方法：利用PAUP*、RAxML、MrBayes、BEAST和RASP等软件对来自2个核区和5个叶绿体DNA区域的数据进行分析。关键结果：我们的分子系统发育支持菊花属单系植物。双叶菊和加拿大菊按其分类学种类划分，而长叶菊则分为两个明确的类群，即一个由北美西部的类群组成，另一个由东北亚的类群组成。分子定年和生物地理重建表明，菊花起源于东北亚，大约在中新世晚期开始了一种复杂的分化进化模式。在上新世期间，北半球的菊花（Maianthemum s.s.）的洲际分离似乎发生过两次。结论：基于本研究结果，可以设想两种可能的处理方法：(1)将亚洲大菊种群提升到特定等级；或者(2)将三个菊种合并为一个广义的单一种。我们建议将菊作为单一种处理。菊花的生物地理格局和分子定年表明，变异和长距离传播是其进化的关键机制。
PREMISE OF THE STUDY: Understanding the underlying mechanisms for the evolution of intercontinental disjunct patterns has long fascinated botanists. We present a molecular phylogenetic reconstruction of Maianthemum s.l. (including Smilacina) with a focus on Maianthemum s.s. species, which have a disjunct distribution between Eurasia and North America. Within this evolutionary framework, we clarify the systematic classification and biogeographical history of Maianthemum s.s.METHOD: Data from two nuclear and five chloroplast DNA regions were analyzed using the programs PAUP*, RAxML, MrBayes, BEAST, and RASP.KEY RESULTS: Our molecular phylogeny supports M aianthemum s.s. as monophyletic. M aianthemum bifolium and M. canadense are grouped according to their taxonomic species, but the accessions of M. dilatatum are divided into two well-defined groups, i.e., one comprising western North American accessions, and the other composed of northeast Asian accessions. Molecular dating and biogeographic reconstructions suggest a northeast Asian origin for Maianthemum s.s. and that a complicated pattern of divergent evolution began approximately in the late Miocene. Intercontinental disjunctions of Maianthemum s.s. in the Northern Hemisphere appear to have occurred two times during the Pliocene.CONCLUSIONS: Based on our results, two possible ways to treat Maianthemum s.s. species can be envisioned: (1) elevate Asian populations of M. dilatatum to specific rank; or (2) combine the three Maianthemum s.s. species into a broadly defined single species. We recommend treatment of Maianthemum s.s. as a single species. The biogeographic patterns of Maianthemum s.s. coupled with molecular dating suggest both vicariance and long-distance dispersal events as key mechanisms for diversification of the clade.