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

9623638辛普森研究生托德·巴克曼在德克萨斯大学贝丽尔·辛普森的指导下，正在研究东南亚植物进化和分布中的一个有趣问题。该项目的重点是兰花属DendroChilum和20-30种Eurybrachium亚种，它们主要出现在婆罗洲的大岛上，其中许多种在Mt.一个人在基纳巴鲁。实地采集将补充植物标本，以便能够对植物和花卉特征进行详细的形态研究；实地工作利用了John Beaman教授及其马来西亚和印度尼西亚同事的植物区系调查活动。此外，核基因和叶绿体基因的分子(DNA)分析将为测量物种之间的突变差异和推断系统发育关系提供新的数据。苏门答腊岛、爪哇岛和苏拉威西岛以及菲律宾和马来西亚的相关群体也将被研究进行系统发育比较。一个强大的物种系统发展将检验关于这些附生兰花起源的两个相互竞争的假说。一种假说声称婆罗洲的适应性辐射来自单一祖先的引入；第二种假说声称来自婆罗洲周围不同岛屿的多次引入。传统的形态特征与来自DNA测序的新的分子数据的结合保证了更可靠的植物分类和对物种之间的系统发育(系谱)关系的强有力的推断。有了这一系统发展史，就可以分析历史生物地理的模式(迁徙、适应性辐射、物种形成)。巴克曼和辛普森对石竹兰的研究是这种重新焕发活力的植物系统学的又一个例子。***

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. ***