Doctoral Dissertation Research: Multi-Scale Analysis of Gene Flow in the Emergent Aquatic Macrophyte Hymenocallis coronaria

博士论文研究：挺水水生植物 Hymenocallis coronaria 基因流的多尺度分析

• 批准号: 0401799
• 负责人: Kathleen Parker
• 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: 2004
• 资助国家: 美国
• 起止时间: 2004-05-01 至 2007-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0401799&HistoricalAwards=false
• 关键词: Doctoral; Dissertation; Research; Multi; Scale

Water movement, which is the primary seed dispersal agent for many aquatic plants, is unidirectional throughout an upland drainage basin. Models of gene flow based on terrestrial environments, where seed dispersal is often multidirectional, are likely inadequate for representing patterns of gene flow in aquatic plants. Few studies have investigated the influence of unidirectional stream flow on patterns of genetic variation in aquatic plants, however, and these studies have reported contradictory results. Furthermore, gene flow both within and among populations has rarely been examined in stream environments, and many questions remain concerning how these processes function at different scales of analysis. This Doctoral Dissertation Research Improvement project will use molecular techniques to examine gene flow in Hymenocallis coronaria (shoals spider lily), an aquatic plant that occurs in shoal habitats in piedmont streams from Alabama to South Carolina but is absent from several watersheds in the middle of its range. The project's first broad objective is to examine the effects of unidirectional stream flow on genetic structure and gene flow within and among populations of Hymenocallis coronaria. Specifically, a combination of nuclear DNA and chloroplast DNA markers will be used to (1) determine whether genetic variability increases progressively downstream both within and among populations, (2) examine the influence of pollen flow vs. seed flow in stream environments, and (3) test which of three gene flow models best represents the patterns of gene flow among populations. The second broad objective is to examine the effects of habitat characteristics and land-use history on population distribution, genetic structure, and gene flow, and how these factors, in turn, affect microevolutionary processes in an aquatic macrophyte. In concert with molecular techniques, stream discharge, water temperature, turbidity, dissolved oxygen, sediment depth in the channel, shoals lithology, and strike and dip of the shoals rock units will be measured to determine (1) which factors are associated with the absence of Hymenocallis coronaria populations from the middle of the species range, (2) whether the exclusion of populations from the uninhabited drainage basins is of prehistoric origin or result from more recent human-related disturbance, and (3) whether populations in isolated drainages are at a greater risk for extinction with ongoing land-use changes.Hymenocallis coronaria is a rare plant that has a relatively restricted range in the southeastern United States. The plant is protected as a threatened or endangered species by the states of Alabama and Georgia. It is listed as imperiled by the state of South Carolina; and protection has been sought under the Endangered Species Act. Documented population extinctions have occurred due to reservoir impoundment, and populations continue to be threatened by further water resource development. In addition to providing information about gene flow in aquatic environments, this research will further basic understanding of the response of this relatively rare species to changing environmental conditions within its range. The results also will inform resource managers as they formulate policy that affects not only this particular state-level endangered botanical resource but potentially other aquatic plants throughout the region affected by the same set of disturbances. 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.

水流动是许多水生植物的主要种子分散剂，在高地排水盆地中是单向的。 基于陆生环境的基因流量模型，种子散布通常是多向的，可能不足以代表水生植物中基因流的模式。 然而，很少有研究研究单向流流对水生植物遗传变异模式的影响，但是这些研究报告了矛盾的结果。 此外，在流环境中很少研究基因在种群内部和人群中的流动，并且关于这些过程如何在不同的分析范围内运作的许多问题仍然存在。 该博士论文研究改进项目将使用分子技术来检查雌性炎的基因流动（浅滩蜘蛛百合），这是一种在阿拉巴马州到南卡罗来纳州的浅滩栖息地中发生的水生植物，但在其范围的几个流水中都没有。 该项目的第一个广泛目标是检查单向流动流对雌性脑炎的遗传结构和基因流的影响。 具体而言，将使用核DNA和叶绿体DNA标记的组合来（1）确定遗传变异性是否在种群内部和种群之间逐渐下游逐渐增加，（2）检查了流媒体环境中花粉流动与种子流的影响，（3）三种基因流量中的哪个基因流量中的哪些最能代表群体中的基因流量模型。 第二个广泛的目标是检查栖息地特征和土地利用历史对种群分布，遗传结构和基因流的影响，以及这些因素如何影响水生大植物中的微进化过程。 将衡量与分子技术，流排水，水温，浊度，溶解的氧气，河流中的沉积物深度，浅滩的岩性以及浅滩岩石单位的罢工和倾角和倾斜从最近与人类相关的干扰以及（3）孤立排水中的种群是否在持续的土地利用变化中面临更大的灭绝风险。Hymenocalliscoronaria是一种罕见的植物，在美国东南部具有相对受限的范围。 该植物受到阿拉巴马州和佐治亚州的威胁或濒危物种的保护。 它被南卡罗来纳州列为危机；并根据《濒危物种法》寻求保护。 由于水库的蓄水，已经发生了有记录的人口灭绝，并且人口继续受到进一步的水资源开发的威胁。 除了提供有关水生环境中基因流动的信息外，这项研究还将进一步理解这种相对罕见的物种对在其范围内改变环境条件的反应。 结果还将在资源经理制定政策时向不仅影响这种特定州级濒危植物资源的政策，而且会影响整个地区受相同干扰影响的其他水生植物。 作为博士学位论文研究改进奖，该奖项还将提供支持，使有前途的学生能够建立强大的独立研究职业。