Phylogenetic Systematics and Biogeography of Asclepias

鱼腥草是北美温带地区著名的开花植物。它们已被传粉生物学家、进化生物学家和化学生态学家广泛研究，并作为植物-昆虫共同进化研究的模式系统。它们可能最为人所知的是帝王蝶的寄主植物--发现了黄花产生的心脏糖苷的作用，并由帝王用来对抗鸟类捕食者，这是进化生态学的经典发展。然而，对马利筋物种关系的研究远远落后于马利筋种群生物学和化学研究的巨大进步。通过对马利筋物种之间的系统发育关系的调查，将对研究充分的生态和进化过程以及评估这些现象的普遍性的能力有更深的理解。密西西比州立大学的Mark Fishbein博士的研究将改进马利筋属(Asclepias)的分类，分析过去和现在的杂交，并阐明北美和非洲物种之间的生物地理联系。Asclepias的系统发育将被用作回答几个关键的进化和生物地理学问题的框架：1)所有的美洲乳草都来自单一的非洲殖民者，还是在美国物种中代表了几个非洲祖先的血统？2)乳草是通过北大西洋交叉还是经由南美洲到达北美？以及3)是否有证据表明形态上不同的不再能够杂交的物种之间过去的杂交和渗透？阐明Asclepias的进化史将给我们提供重要的洞察，了解这个群体已经产生了无处不在的杂草和北美一些最稀有的物种。这也将为未来研究黄花和它们的专业昆虫食草动物的共同进化提供重要的基础。这个项目的结果可能会影响到系统学、进化论和生态学以外的学科。马利筋越来越多地被用作园艺多年生植物和切花。增加对马利筋关系的了解，将通过确定可用既定方案种植的栽培物种的近亲，促进新园艺材料的开发。将加强以黄花为基础的植物化学研究，特别是针对农药开发的研究。由于Asclepias物种作为帝王蝶主要寄主植物的重要性，该项目将有助于保护受威胁的帝王蝶种群。与墨西哥同事扎穆迪奥·鲁伊斯和英国同事D·J·戈伊德的实地和实验室工作将加强国际合作。此外，国际生物研究所正在开发乳草作为一个模型系统，以了解物种之间如何发生杂交，这对于了解转基因生物的生态影响至关重要。这个项目将对分子系统学和进化生物学的研究生和本科生的培训产生重大影响。密西西比州立大学提供了一个极好的机会来增加生物科学中代表性不足群体的研究机会。学生将在地区和国家会议上展示他们的研究成果。

0415213Fishbein Milkweeds are well known flowering plants of temperate North America. They have been widely studied by pollination biologists, evolutionary biologists, and chemical ecologists, and have served as a model system in studies of plant-insect coevolution. They are perhaps best known as the host plant of the Monarch butterfly - the discovery of the role of cardiac glycosides produced by milkweeds and sequestered by Monarchs for use against avian predators was a classic development in evolutionary ecology. However, research on milkweed species relationships has lagged far behind the tremendous progress in studies of the population biology and chemistry of milkweeds. A much deeper understanding of well-studied ecological and evolutionary processes and the ability to assess the generality of these phenomena will be gained from this investigation of the phylogenetic relationships among milkweed species. Research by Dr. Mark Fishbein at Mississippi State University will result in an improved classification of the milkweed genus (Asclepias), analyses of past and current hybridization, and elucidation of the biogeographic link between North American and African species. The inferred phylogeny of Asclepias will be used as a framework for answering several key evolutionary and biogeographic questions: 1) Are all American milkweeds derived from a single African colonist, or are several ancestrally African lineages represented among the American species?, 2) Did milkweeds arrive in North America via a North Atlantic crossing or via South America?, and 3) Is there evidence for past hybridization and introgression between morphologically disparate species that are no longer capable of hybridization? Elucidating the evolutionary history of Asclepias will give important insights into a group that has given rise to ubiquitous weeds and some of the rarest species in North America. It also will provide a crucial basis for future studies of the coevolution of milkweeds and their specialist insect herbivores. The results of this project will likely impact disciplines beyond systematics, evolution, and ecology. Milkweeds are increasingly being used in horticulture as garden perennials and cut flowers. Increased understanding of milkweed relationships will foster development of new horticultural materials by identifying close relatives of cultivated species that can be grown using established protocols. Studies of plant chemistry based on milkweeds will be enhanced, especially research targeting pesticide development. Because of the importance of Asclepias species as the primary host plant of the Monarch butterfly, this project will contribute to the conservation of threatened Monarch butterfly populations. Field and laboratory work with Mexican colleague Zamudio Ruiz and British colleague D. J. Goyder will enhance international collaboration. In addition, the PI is developing milkweed as a model system for understanding how hybridization occurs between species, which is critical for understanding the ecological impacts of genetically modified organisms. This project will significantly impact graduate and undergraduate training in molecular systematics and evolutionary biology. Mississippi State University provides an excellent opportunity to increase the research opportunities of underrepresented groups in biological sciences. Students will present the results of their research at regional and national meetings.