Dissertation Research: Evolution of Dendrochilum Orchids on Mt. Kinabalu Examined in a Phylogenetic Context

小行星9623638 研究生托德巴克曼在得克萨斯大学顾问贝丽尔辛普森的指导下，正在研究东南亚植物进化和分布的一个有趣问题。 该项目的重点是兰花属Dendrochilum和20 - 30种主要出现在婆罗洲大岛的Eurybrachium亚组，其中许多在Mt.只有京那巴鲁。 野外采集将增加植物标本室的材料，使植物和花卉特征的详细形态学研究;野外工作利用了John Beaman教授及其马来西亚和印度尼西亚同事的植物区系编目活动。 此外，核和叶绿体基因的分子（DNA）分析将增加新的数据，用于测量物种之间的突变差异和推断系统发育关系。 在苏门答腊岛，爪哇岛，苏拉威西岛，以及在菲律宾和马来西亚的相关群体也将进行系统发育比较研究。 一个强大的物种的进化将测试两个相互竞争的假设，这些附生兰花的起源。 一种假设声称婆罗洲的适应性辐射来自单一的祖先引入;第二种假设声称婆罗洲周围不同岛屿的多个引入。 %%% 传统的形态特征与DNA测序的新分子数据的整合，保证了一个更可靠的植物分类和物种之间的系统发育（系谱）关系的强有力的推断。 有了这个系统发生学，历史地理学的模式（迁移、适应性辐射、物种形成）就可以被分析出来。 Barkman和Simpson对Dendrochilum兰花的研究是这种再生植物系统学的另一个例子。 ***

9623638 Simpson Graduate student Todd Barkman, with direction from adviser Beryl Simpson at the University of Texas, is studying an interesting problem in plant evolution and distribution in Southeast Asia. The focus of the project is the orchid genus Dendrochilum and the 20-30 species of subsection Eurybrachium that occur mostly on the large island of Borneo, with many on Mt. Kinabalu alone. Field collections will augment herbarium materials to enable detailed morphological study of vegetative and floral characters; field work capitalizes on the floristic inventory activities of Prof. John Beaman and his Malaysian and Indonesian colleagues. In addition, molecular (DNA) analyses of nuclear and chloroplast genes will add new data for measuring mutational differences between the species and for inferring phylogenetic relationships. Related groups on the islands of Sumatra, Java, and Sulawesi, and in the Philippines and Malaysia will also be studied for phylogenetic comparisons. A robust phylogeny of the species will test two competing hypotheses for the origin of these epiphytic orchids. One hypothesis claims adaptive radiation on Borneo from a single ancestral introduction; the second hypothesis claims multiple introductions from different islands around Borneo. %%% The integration of traditional morphological characters with new molecular data from DNA sequencing promises a more reliable taxonomy of plants and the robust inference of phylogenetic (genealogical) relationships among species. With this phylogeny in place, patterns of historical biogeography (migration, adaptive radiations, speciation) can be analyzed. Barkman and Simpson's study of Dendrochilum orchids is one further example of this rejuvenated plant systematics. ***