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

博士论文研究：通过森林林下植物延龄草的系统发育地理学分析识别冰川保护区

• 批准号: 0327147
• 负责人: James Hamrick
• 金额: $ 1.2万
• 依托单位: University of Georgia Research Foundation Inc
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-09-01 至 2005-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0327147&HistoricalAwards=false
• 关键词: Doctoral; Dissertation; Research; Identification; Glacial

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.

遗传变异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，历史的、古生态的和生物地理的观点往往没有被包括在这些解释中。随着分子遗传标记阵列的可用性与先进的分析方法相结合，现在有可能将生物地理学和古生态学的观点与群体遗传和系统发育分析结合起来。这种方法体现在系统地理学（生物地理学的一个分支学科）中。本博士论文的研究目的是结合母系遗传的叶绿体DNA和双亲本遗传的同工酶标记，研究森林林下植物万里草（Trillium cuneatum, Melanthiaceae）的系统地理学和冰川避难史。这项研究将证明种群是如何在物种的地理范围内相互关联的，从而可以推断过去的避难所和冰川后的殖民模式。本项目的目标是：(1)确定冰川避难所的数量和位置；(2)推断冰期后殖民路线模式；(3)描述避难世系的重叠程度和种群内多态性。确定过去的范围收缩和避难所扩张对于理解塑造当代生物多样性分布的生物地理和进化过程具有重要意义。通过同时研究遗传多样性的空间和时间分布，该项目将证明最后一次冰川高峰时期的避难地点，并将确定这一时期之后的古代迁徙模式。因此，这项研究将为当代遗传分化的解释提供一个历史的生物地理背景。该项目还补充了对南阿巴拉契亚生物多样性的研究（由国家公园管理局进行），提供了对美国东南部植被历史和生物多样性的见解。例如，广泛的物种是否在最后一次冰川高峰后传播到南阿巴拉契亚，或者这些物种是否起源于小型的原位避难所的问题，对有效管理丰富的东南部植物群具有重要意义。此外，通过深入了解形成当代遗传变异的过程，这项研究将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区域和全球气候变化模式，加上详细的遗传分析，将确定物种对气候变化响应的相似性和差异性。这些信息的积累可以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研究生涯。