Dissertation Research: Systematics and Evolution of the Genus Waltheria (Sterculiaceae)

学院顾问Beryl Simpson博士和研究生Jan 桑德斯将研究热带树属Waltheria和相关的 物种，利用植物标本馆标本和新的实地收集， 在巴西. 由于该属知之甚少，工作将集中在 改进的物种描述，地理分布图， 识别键，以及关于进化的推论 估计有50个物种的关系，其中25个发生在 巴西 由此产生的分类学专著也将解决 120个科学名称的命名，目前适用于 这些植物遍布世界各地。 此外，不寻常的繁殖系统 两种不同的花型（两种不同的花型，在不同的植物上）， 研究了 针形植物的花有长花柱和短花柱， 雄蕊，而thrum植物承担短风格的花朵， 长雄蕊。 花的二型性通常是由一个 双等位孢子体不亲和系统表基因， 减少了植物内部可能发生的近亲繁殖 人口 在这项研究中， 针和thrum形式在几个物种将进行分析 广泛地，尤其是花粉。 可分阶段进行 在研究过程中，还将研究distyly的演变。 对中国的Waltheria和近缘属的比较分析 梧桐科

Faculty adviser Dr. Beryl Simpson and graduate student Jan Saunders will study the tropical tree genus Waltheria and related species, using herbarium specimens and new field collections made in Brazil. Because the genus is poorly known, work will focus on improved species descriptions, maps of geographic distribution, identification keys, and inferences about evolutionary relationships of the estimated 50 species, 25 of which occur in Brazil. The resultant taxonomic monograph will also resolve the nomenclature of the 120 scientific names currently applied to these plants worldwide. In addition, the unusual breeding system of distyly (two floral forms, on separate plants) will be studied. Pin plants bear flowers with long styles and short stamens, whereas thrum plants bear flowers with short styles and long stamens. The floral dimorphism typically is linked by a supergene to a diallelic sporophytic incompatibility system which reduces the amount of inbreeding that can occur within a plant population. In this study, the morphological differences between pin and thrum forms in several species will be analyzed extensively, especially the pollen. Possible stages in the evolution of distyly will also be studied, in the course of comparative analyses of Waltheria and related genera of the Sterculiaceae family.