Doctoral Dissertation Research: Identification of Glacial Refugia by Phylogeographic Analyses of the Forest Understory Plant Species, Trillium Cuneatum

遗传变异的地理模式的描述和解释在植物进化生物学中占有中心地位。 然而，历史、古生态学和地理学的观点往往没有包括在这些解释中。 随着分子遗传标记阵列与先进的分析方法相结合的可用性，现在有可能将地理学和古生态学观点与种群遗传和系统发育分析相结合。 这种方法体现在地理学的学科中（地理学的一个分支学科）。 本博士论文研究项目的目标是联合收割机分析母系传递的叶绿体DNA和双亲遗传的等位酶标记，调查森林林下物种，延龄草（Melanthiaceae）的冰川地理和冰川避难所的历史。 这项研究将展示种群如何在物种的地理范围内相互关联，从而推断过去的避难所和冰川后的殖民模式。 本计画的目标是：（1）确定冰河避难所的数量与位置;（2）推断冰河期后殖民路线的模式;（3）描述重叠程度和内部-避难所谱系的种群多态性。确定过去的范围收缩和避难所扩张对于理解塑造当代的地理和进化过程具有重要意义。生物多样性的分布。 通过同时检查遗传多样性的空间和时间分布，该项目将证明在最后一次冰期最大的避难所的位置，并将确定这一时期之后的古代迁移模式。 因此，这项研究将提供一个历史地理背景的解释当代遗传分化。 该项目还补充了南阿巴拉契亚生物多样性的研究（由国家公园管理局进行）通过提供对美国东南部植被历史和生物多样性的见解。例如，广泛分布的物种是否在末次盛冰期后扩散到阿巴拉契亚山脉南部，或者这些物种是否起源于小的原地避难所，这一问题对有效管理丰富的物种具有重要意义。东南部植物群。 此外，通过深入了解塑造当代遗传变异的过程，这项研究应该有助于预测生物对未来全球气候变化的反应。 从第四纪和全新世早期化石记录中推断出的气候变化的区域和全球模式，加上详细的遗传分析，将确定物种对气候变化反应的相似性和差异。 这种资料的积累可能产生未来气候变化的类似物，从而有助于评估预期的变化。 作为博士论文研究改进奖，该奖项还将提供支持，使有前途的学生建立一个强大的独立的研究生涯。

The description and interpretation of geographic patterns of genetic variation have occupied a central position in plant evolutionary biology. Historical, paleoecological, and biogeographical perspectives often have not been included in these interpretations, however. With the availability of arrays of molecular genetic markers combined with advanced analytical procedures, it is now possible to couple biogeographical and paleoecological perspectives with population genetic and phylogenetic analyses. This approach is embodied in the discipline of phylogeography (a subdiscipline of biogeography). The goal of this doctoral dissertation research project is to combine analyses of maternally transmitted chloroplast DNA and bi-parentally inherited allozyme markers to investigate the phylogeography and glacial refugial history of the forest understory species, Trillium cuneatum (Melanthiaceae). This study will demonstrate how populations are related across the species' geographic range, allowing inference of past refugia and post-glacial colonization patterns. Objectives of this project are: (1) to identify the number and locations of glacial refugia; (2) to infer patterns of post-glacial colonization routes; and (3) to describe the degree of overlap and intra-population polymorphism of refugial lineages.Determination of past range contractions and refugial expansions has important implications for understanding the biogeographical and evolutionary processes that have shaped the contemporary distribution of biodiversity. By simultaneously examining the spatial and temporal distribution of genetic diversity, this project will testify to refugial locations during the last glacial maximum and will identify ancient migration patterns following this period. The research therefore will provide a historical biogeographical context for the interpretation of contemporary genetic divergence. This project also complements studies of Southern Appalachian biodiversity (conducted by the National Park Service) by providing insights into the vegetation history and biodiversity of the southeastern U.S. For example, the question of whether widespread species spread into the Southern Appalachians after the last glacial maximum or whether these species originated from small in situ refugia has important implications for the effective management of the rich southeastern flora. Furthermore, by developing insights into the processes that have shaped contemporary genetic variation, this study should prove useful in predicting biotic responses to future global climatic changes. Regional and global patterns of climatic change inferred from the Quaternary and early Holocene fossil records coupled with detailed genetic analyses will identify similarities and differences between species in their response to climate change. The accumulation of such information may yield analogues for future climatic change, and, thus assist the evaluation of the anticipated changes. As a Doctoral Dissertation Research Improvement award, this award also will provide support to enable a promising student to establish a strong independent research career.