Phylogenetic Systematics and Biogeography of Asclepias

0415213 Fishbein Milkweeds是众所周知的北美温带开花植物。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，并已成为植物-昆虫协同进化研究的模型系统。它们可能是最有名的帝王蝶的宿主植物--乳草产生的强心苷的作用被帝王蝶隔离，用于对抗鸟类捕食者，这是进化生态学的一个经典发展。然而，对马利筋种间关系的研究却远远落后于马利筋种群生物学和化学研究的巨大进展。一个更深入的了解研究生态和进化过程，并能够评估这些现象的一般性将获得从本调查的马利筋物种之间的系统发育关系。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地理联系。马利筋的进化史将被用来回答几个关键的进化和地理学问题：1）所有的美洲乳草都来自一个单一的非洲殖民者，还是几个祖先非洲血统在美洲物种中代表？2)马利筋是通过北大西洋还是通过南美洲到达北美的？，是否有证据表明，在形态上不同的物种之间，过去的杂交和渐渗不再能够杂交？阐明Asclepias的进化历史将对一个引起北美无处不在的杂草和一些最稀有物种的群体提供重要的见解。这也将为今后研究乳草及其专业食草昆虫的共同进化提供重要的基础。 该项目的结果可能会影响系统学，进化和生态学之外的学科。马利筋越来越多地被用于园艺作为花园多年生植物和切花。对马利筋关系的进一步了解将通过确定可以使用既定协议种植的栽培物种的近亲来促进新园艺材料的开发。将加强以马利筋为基础的植物化学研究，特别是针对农药开发的研究。由于马利筋属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Zamudio Ruiz和英国同事D. J. Goyder将加强国际合作。此外，PI正在开发乳草作为了解物种间杂交如何发生的模型系统，这对于了解转基因生物的生态影响至关重要。该项目将对分子系统学和进化生物学的研究生和本科生培训产生重大影响。密西西比州立大学提供了一个极好的机会，以增加生物科学中代表性不足的群体的研究机会。学生将在区域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.