RUI: Phylogeography of Hawaiian Schiedea: A Multigene Coalescent Approach

Drs。南达科他州大学的Nepokroeff和Wallace计划研究夏威夷特有植物属Schiedea的系统发育和系统地理（“系谱”）关系。Schiedea代表了一个很好的模型系统，用于研究岛屿上的物种多样化，因为该属包括来自单一假定祖先的最大的植物物种辐射之一（30种左右），并且在生长形式，繁殖系统和栖息地偏好方面是最多样化的。对斯切迪亚传粉系统生态学的研究已成为岛屿上主要进化转变的经典例子。Schiedea谱系特别有趣，因为它包含了许多表现出花的二态性（雄性和雌性植物分开）的物种，这在人类和大多数动物中是正常的，但在开花植物中却很少见。然而，在种间的关系，从而过渡到花二态的数量和顺序仍然很不清楚。研究人员计划使用来自几个核和质体基因组来源的6个DNA标记来检查现存的33个Schiedea物种之间的关系。此外，研究人员计划通过对谱系中几个密切相关的成员进行抽样，并在一个聚结框架内分析这些关系，来检查种内谱系，这是一种新描述的检查种群内基因历史的方法。研究人员使用的方法将允许增加，如果不是完整的，系统发育和系谱之间的物种的决议。此外，所使用的方法将使研究人员能够评估一些微观进化过程，如种间基因流动和杂交，这些过程可能有助于物种多样化和花二态性的进化。由于植物系统地理学的研究不如动物系统地理学深入，本研究将为植物系统地理学的发展做出贡献。该项目将在统计系统地理学这一新兴领域培养一名女性博士后。将为10名学生提供本科生参与的机会，他们将接受实验室技能、数据分析、研究报告和手稿准备方面的培训。南达科他州大学主要服务于一个农村社区，有许多第一代大学生和很高比例的美国印第安人学生，包括一名目前攻读荣誉生物学专业的学生，他将对Schiedea进行独立研究。为了促进这些研究和教育目标，国家科学基金会EPSCoR项目的共同资助有助于支持该项目。最后，在33种Schiedea谱系中，超过一半的物种处于联邦濒危或稀有状态，其中一些已经在野外灭绝；事实上，与夏威夷的任何其他谱系相比，希迪亚可能包含更多受到高度威胁的植物物种。这些研究将导致14种濒危物种的栖息地适宜性模型的公开开发，这些模型与夏威夷植物区系的几个现有网站相连。除了综合遗传信息和景观水平信息外，这些模型还有可能被国家机构用于恢复计划，并将为本科生提供景观建模方面的额外培训。

Drs. Nepokroeff and Wallace at the University of South Dakota plan to examine both phylogenetic and phylogeographic ("genealogical") relationships in the endemic Hawaiian plant genus Schiedea. Schiedea represents an excellent model system for examining species diversification on islands as the genus comprises one of the largest radiations of plant species (30 or so species) from a single presumed ancestor, and is one of the most diverse in terms of growth form, breeding systems, and habitat preferences. Studies of the ecology of pollination systems in Schiedea have become classic examples of major evolutionary transitions on islands. The Schiedea lineage is particularly interesting because it contains many species which exhibit floral dimorphism (separate male and female plants), the norm in humans and most animals, but rare in flowering plants. However, relationships among species of Schiedea, and thus number and order of transitions to floral dimorphism remain poorly resolved. The investigators plan to examine relationships among the 33 extant species of Schiedea using six DNA markers from several nuclear and plastid-genome sources. Additionally, the investigators plan to examine intraspecific genealogies by sampling populations of several closely related members of the lineage and analyzing these relationships within a coalescent framework, a newly described method for examining the history of genes within populations. The approach used by the investigators will allow for increased, if not complete, phylogenetic and genealogical resolution among species of Schiedea. Moreover, the approach used will enable the investigators to assess a number of microevolutionary processes, such as interspecific gene flow and hybridization, that may have contributed to species diversification and evolution of floral dimorphism.Because plant phylogeography is less well-studied than that of animals, this study will contribute to the developing field of plant phylogeography. The project will involve training for one female postdoctoral associate in the emerging field of statistical phylogeography. Opportunity for undergraduate involvement will be provided for ten students, who will receive training in laboratory skills, data analysis, research presentation and manuscript preparation. The University of South Dakota serves a predominantly rural community, with many first-generation college students and a high proportion of American Indian students, including one current Honors Biology major who will be pursuing independent research on Schiedea. In furtherance of these research and educational goals, co-funding from the NSF program for EPSCoR helps support this project. Lastly, over half of the 33 species in the Schiedea lineage are federally endangered or rare and several have already gone extinct in the wild; indeed Schiedea may contain more highly threatened plant species that any other lineage in Hawaii. These studies will result in development of publicly available, online graphical habitat-suitability models of 14 endangered species of Schiedea, linked to several existing websites of the Hawaiian flora. In addition to synthesizing genetic information with landscape level information, such models have the potential to be used in recovery plans by state agencies, and will provide additional training to undergraduates in landscape modeling.