Dissertation Research: Molecular Systematics of Artemisia Sect. Tridentatae

9311086 Watson Artemesia (sensu lato) L.由约400种组成，分布在世界北温带地区。它是菊花科（菊科）中最大和生态最重要的属。该属一直是众多比较生物系统调查的主题，但仍然知之甚少。三叉戟科原产于北美西部，在山艾树群落中起着重要的生态作用。三叉戟科由11种旱生灌木组成，通过同质花头的存在与其他北美物种区分开来。三叉戟科植物的迅速扩张和分化，加上风媒传粉，导致了广泛的趋同和平行进化。这使得解释系统发育关系变得困难。本研究的主要目的是阐明三叉戟科的种间系统发育关系，并确定三叉戟科与蒿属其他亚属分类群和分离属Seriphidium的亲缘关系。将使用几种分子技术，包括叶绿体DNA和核糖体DNA限制性位点图的系统发育分析以及cpDNA基因组ORFk（开放阅读框k）区域的序列数据分析。先前提出的三齿动物进化关系的假设将使用分子数据的分支分析进行测试。对基于细胞质和核标记的种间关系系统发育之间的一致性的检查将用于测试提出的物种形成模式和检查特征进化模式。推断出的系统发生将有助于理解北美西部寒冷沙漠中三叉戟动物的进化和生态成功。本项目将获得蒿属三叉戟科11种荞属植物的叶绿体和细胞核基因组数据。这些数据将被用来确定这些物种之间的关系，当形态学特征被用来建立关系时，这些物种之间的关系一直是一些混乱的主题。这些木本灌木是寒冷荒漠生态系统中非常明显的重要组成部分，了解物种关系将促进这些植物在生态学和生物地理学方面的其他研究。＊＊＊

9311086 Watson Artemesia ( sensu lato ) L. is composed of approximately 400 species distributed throughout the north temperate regions of the world. It is the largest and ecologically most important genus in the Tribe Anthemideae (Asteraceae). The genus has been the subject of numerous comparative biosystematic investigations, but remains poorly understood. Section Tridentatae is native to western North America and plays an important ecological role in the sagebrush communities. Tridentatae is composed of 11 species of xerophytic shrubs, separated from the other North American species by the presence of homogamous flower heads. The rapid expansion and divergence of Tridentatae , coupled with wind pollination has resulted in extensive convergence and parallel evolution. This has made interpretation of phylogenetic relationships difficult. The main objectives of this study are to elucidate interspecific phylogenetic relationships within Tridentatae , and to determine the affinity of Tridentatae to other subgeneric taxa of Artemesia and to the segregate genus Seriphidium . Several molecular techniques will be utilized including phylogenetic analysis of chloroplast DNA and nuclear ribosomal DNA restriction site maps and analysis of sequence data from the ORFk (Open Reading Frame k) region of the cpDNA genome. Previously proposed hypotheses of evolutionary relationships of Tridentatae will be tested using cladistic analyses of molecular data. An examination of concordance between cytoplasmic and nuclear marker based phylogenies of interspecific relationships will be used to test proposed modes of speciation and to examine patterns of character evolution. The inferred phylogenies will be useful in understanding the evolutionary and ecological success of Tridentatae in the cold deserts of western North America. %%% This project will obtain molecular data (both from the chloroplast and nuclear genomes) for 11 species of sagebrush in the Section Tridentatae of the genus Artemesia . These data will be used to decide relationships among these species that have been the subject of some confusion when morphological characters have been used to establish relationships. These woody shrubs are a highly visible and important component of the cold desert ecosystem and understanding species relationships will enhance other research efforts in ecology and biogeography of these plants. ***