Dissertation Research: Systematics and Flower Development in the Milkweed Tribe Gonolobeae (Asclepiadaceae)

在华盛顿大学的Barbara Schaal博士和密苏里州植物园的Peter Raven博士的指导下，Schaal、Raven和Prince zie的研究生Thomas impzie正在研究一组新热带马利筋藤本植物(Asclepiadaceae中的Gonolobeae部落)的进化关系和花形态。由于花部分之间的复杂融合和独特的冠状结构的存在，乳草花高度专门化。在德克萨斯州和墨西哥南部的田野工作期间，普林齐收集了大约60个品种的鲜花，这让他能够使用标准的解剖切片技术和扫描电子显微镜非常详细地研究它们的结构。通过在发育的多个阶段收集信息，还将有可能追踪各种日冕结构的起源，其多样性在过去曾令分类学家感到困惑。这项研究的第二个组成部分是根据两个独立的核基因和叶绿体基因的DNA序列数据重建这一米草部落的进化史。由此产生的系统发育信息将补充在该科和密切相关科的更高分类水平上进行的其他研究。通过在独立建立的系统发育的框架内研究花的结构和发育，将有可能阐明导致其巨大多样性的进化变化，并阐明发育变化作为多样化机制的作用。

Schaal, Raven, and Prinzie Graduate student Thomas Prinzie, under the direction of Dr. Barbara Schaal at Washington University and Dr. Peter Raven at the Missouri Botanical Garden, is studying the evolutionary relationships and flower morphology of a neotropical group of milkweed vines (tribe Gonolobeae in the family Asclepiadaceae). Milkweed flowers are highly specialized as a result of complex fusion between floral parts and the presence of unique corona structures. During field work in Texas and Southern Mexico, Mr. Prinzie has collected fresh flowers of some 60 species, allowing him to study their structure in great detail using both standard anatomical sectioning techniques and scanning electron microscopy. By collecting information at many stages of development, it will also be possible to trace the origin of the various corona structures, whose diversity has confused taxonomists in the past. A second component of the research consists in reconstructing the evolutionary history of this tribe of milkweeds, on the basis of DNA sequence data from two separate nuclear and chloroplast genes. The resulting phylogenetic information will complement other studies being performed at higher taxonomic levels in this and closely related families. By studying the structure and development of Gonolobeae flowers in the framework of an independently established phylogeny, it will be possible to clarify the evolutionary modifications that gave rise to their great diversity, and to illustrate the role of developmental changes as a mechanism of diversification.