Dissertation Research: Austral Biogeography: The Evolution of Subalpine Ourisia (Scrophulariaceae) in a Phylogenetic Context

摘要(字数：223)自从150多年前博物学家约瑟夫·道尔顿·胡克探索南部大陆以来，生物学家一直对了解南美洲南部、澳大拉西亚和/或非洲相关生物的当前分布感兴趣。有人争辩说，这种南半球的生物地理格局与8000万年前冈瓦那的替代分裂有关，但另一个相互竞争的假说表明，同样的格局可能是最近通过长距离扩散而出现的。化石证据和系统发育研究的结果证实了一些木本林类群的替代模式，但很少有研究集中在南部地区海拔较高的草本植物属上。有人提出，这些高山草本植物可能不是广布的冈瓦那植物区系的遗迹，而是最近事件的结果。高山群可能是最近的，因为这些草本植物生长在只有在新西兰和南美洲的高海拔山脉最后一次第四纪隆起后才存在的生境中。亚高山草本植物Ourisia(玄参科)由大约35种不同的物种组成，分布在从委内瑞拉到火地岛、新西兰山脉和塔斯马尼亚高海拔地区的南美安第斯山脉。我们将使用DNA序列数据和形态来重建Ourisia的进化史，以研究替代和扩散假说，作为对该属南端生物地理的潜在解释。意义(字数：235)我们对玄参属(玄参科)的全面系统发育研究为我们提供了一个宝贵的机会来扩大我们对南侧生物地理格局的理解。大多数表现出这种南方分布的植物群的生物地理研究集中在木本森林群，如Nothofagus(Nothofagaceae)，Araucaria(Araucariaceae)，以及与Atherospermataceae密切相关的属。虽然贡德瓦南替代是这些古老群体的一个很好的模式，但它可能不适用于高海拔草本植物，如Ourisia，它们占据的栖息地是较新的第四纪起源的。除了它的生物地理意义外，我们的研究还将允许我们检查Ourisia内的一些进化模式。由于Ourisia在花形态、染色体数目、习性和营养性状上表现出丰富的多样性，因此，全面的形态研究将为该属的特征进化提供新的见解。我们还将研究新西兰和南美洲山区物种的辐射模式，并讨论Ourisia的系统发育模式与当前或历史障碍、地质和气候相一致的地区的一般影响。因此，我们的研究将为我们提供一个可以用于：1)更好地了解该属内物种之间的关系，以及该属与其近亲之间的关系；2)研究该属的生物地理和评估每个地理区域内的辐射模式；以及3)调查该属的染色体数目和形态特征的进化。

Summary (word count: 223) Ever since naturalist Joseph Dalton Hooker explored the southern continents over 150 years ago, biologists have been interested in understanding the current distributions of related organisms in southern South America, Australasia, and/or Africa. It has been argued that this austral biogeographic pattern is associated with the vicariant breakup of Gondwana that began over 80 million years ago, but a competing hypothesis suggests that the same pattern might have arisen more recently via long-distance dispersal. Fossil evidence and results from phylogenetic studies corroborate the vicariance paradigm for some woody forest groups, but few studies have focused on higher elevation herbaceous genera in southern regions. It has been suggested that these alpine herbs may not be relics of a widespread Gondwana flora, but rather the result of more recent events. Recentness is likely in alpine groups because these herbs occur in habitats that have existed only since the final Quaternary uplift of high-elevation mountains in New Zealand and South America. The subalpine, herbaceous genus Ourisia (Scrophulariaceae) comprises about 35 different species that are distributed throughout the South American Andes from Venezuela to Tierra del Fuego, the mountains of New Zealand, and high-elevation regions of Tasmania. We will reconstruct the evolutionary history of Ourisia using DNA sequence data and morphology to investigate vicariance and dispersal hypotheses as potential explanations for the austral biogeography of the genus. Significance (word count: 235) Our comprehensive phylogenetic study of Ourisia (Scrophulariaceae) presents a valuable opportunity to expand our understanding of the austral biogeographic pattern. Most biogeographic studies of plant groups that exhibit this southern distribution have focused on woody forest groups such as Nothofagus (Nothofagaceae), Araucaria (Araucariaceae), and closely related genera in Atherospermataceae. Although Gondwanan vicariance is a good model for these ancient groups, it may not apply to high-elevation herbaceous plants such as Ourisia that occupy habitats that are of more recent Quaternary origin. In addition to its biogeographical significance, our study will also allow us to examine some evolutionary patterns within Ourisia. Because Ourisia exhibits ample variation in floral morphology, chromosome number, habit, and vegetative characters, a comprehensive morphological study will provide new insights into character evolution in the genus. We will also examine radiation patterns of species in the mountains of New Zealand and South America, and discuss the general implications of areas where the phylogenetic pattern of Ourisia is congruent with current or historical barriers, geology, and climate. Our study will thus provide a reconstruction of the evolutionary history of Ourisia that we can use to: 1) provide a better understanding of the relationships of species within the genus, and between Ourisia and its closest relatives, 2) examine the biogeography of Ourisia and assess patterns of radiation within each geographical region, and 3) investigate evolution of chromosome number and morphological characters in the genus.