Dissertation Research: Systematics and Biogeography of Mentzelia (Loasaceae): A North and South American Desert Disjunct

Mentzelia是新大陆为数不多的两栖植物之一 被认为起源于北美的间断词， 将检查遗传差异， 系统发育关系研究生爱丽丝 亨佩尔，在顾问罗伯特詹森的监督下， 在德克萨斯大学。 审查这些新的 使用DNA限制性位点的世界分离 信息以前没有做过。 使用 叶绿体DNA、核核糖体DNA和 形态数据将生成三个独立的数据 研究可能导致 电流分布，如长距离 扩散，vicariance事件，残余分布和 趋同进化 间断种和属 在干旱和半干旱地区 北美和南美的土地，但没有强大的 这些分类群存在着解释 地理过程。 该项目旨在 回答系统学问题，如关系 在Loasaceae三个亚科之间， 在Mentzelia和sect.Mentzelia内的物种， 包含了大多数南美物种。 一 修订组。Mentzelia，包括分子， 需要染色体和SEM种皮数据， 完成对该属的现代修订。 形态 和分子数据将分别进行分析， 整合，使用简约的方法。 所得 系统发育树和遗传分化的测量 将被用来评估有关的假设 Mentzelia的分布

Mentzelia, one of the few New World amphitropical plant disjuncts proposed to have originated in North America, will be examined for genetic divergence and phylogenetic relationships by graduate student Alice Hempel, under the supervision of adviser Robert Jansen at the University of Texas. Examination of such New World disjunctions using DNA restriction site information has not been done previously. The use of chloroplast DNA, nuclear ribosomal DNA and morphological data will generate three independent data sets to investigate the potential processes leading to the current distribution such as long distance dispersal, vicariance events, relict distributions and convergent evolution. Disjunct species and genera have been comparatively well documented between the arid lands of North America and South America, but no robust phylogenies exist for these taxa to interpret the biogeographical processes. This project is designed to answer systematics questions such as the relationships between the three Loasaceae subfamilies, the sections in Mentzelia and species within sect. Mentzelia, which contains the majority of South American species. A revision of sect. Mentzelia, including molecular, chromosomal and SEM seed coat data is needed to complete a modern revision of the genus. Morphological and molecular data will be analyzed both separately and integrated, using parsimony methods. The resulting phylogenetic trees and measures of genetic divergence will be used to evaluate the hypotheses regarding the present distribution of Mentzelia.