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

自从150多年前博物学家约瑟夫·道尔顿·胡克探索了南部大陆以来，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。有人认为，这种南方生物地理模式与8000多万年前开始的冈瓦纳大陆的替代分裂有关，但另一种与之竞争的假设认为，同样的模式可能是在最近的远距离分散中出现的。化石证据和系统发育研究结果证实了一些木本森林类群的变异模式，但很少有研究关注南方地区高海拔草本属。有人认为，这些高山草本植物可能不是广泛分布的冈瓦纳植物群的遗迹，而是最近事件的结果。在高山类群中，这些草本植物很可能是最近的，因为这些植物生长在新西兰和南美洲高海拔山脉第四纪最后一次隆起以来才存在的栖息地。亚高山，草本属Ourisia（玄参科）由大约35种不同的物种组成，分布在南美安第斯山脉，从委内瑞拉到火地岛，新西兰山脉和塔斯马尼亚的高海拔地区。我们将利用DNA序列数据和形态学重建欧瑞西亚的进化史，以研究作为该属南方生物地理潜在解释的变异和分散假说。意义（字数：235）我们对玄参科（eurisia）的全面系统发育研究为我们扩大对南方生物地理格局的理解提供了宝贵的机会。大多数对这种南方分布的植物类群的生物地理研究都集中在木本森林类群上，如Nothofagus (Nothofagaceae), Araucaria （Araucariaceae）和Atherospermataceae中密切相关的属。虽然冈瓦南变异是这些古老类群的一个很好的模型，但它可能不适用于高海拔草本植物，如占据较晚的第四纪起源栖息地的欧瑞西亚。除了它的生物地理意义外，我们的研究还将使我们能够研究欧丽西亚的一些进化模式。由于鸢尾花在花形态、染色体数目、习性和营养性状上表现出丰富的变异，对其进行全面的形态学研究将为研究鸢尾属植物的性状进化提供新的思路。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系统发育模式与当前或历史障碍、地质和气候一致的地区的一般含义。因此，我们的研究将为我们提供一个重建史，我们可以利用它来：1)提供一个更好的物种间关系的理解，并在其最接近的亲缘关系，2)检查重建史的生物地理学和评估辐射模式在每个地理区域，3)研究重建史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.