Doctoral Dissertation Research: Reconstructing How Ecosystems Develop in High Northern Latitudes Using Genetic Markers and Temperature Signals in Lake Sediments

博士论文研究：利用湖泊沉积物中的遗传标记和温度信号重建北部高纬度地区生态系统的发展方式

• 批准号: 1657743
• 负责人: Gifford Miller
• 金额: $ 1.6万
• 依托单位: University of Colorado at Boulder
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-03-01 至 2018-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1657743&HistoricalAwards=false
• 关键词: Doctoral; Dissertation; Research; Reconstructing; How

This doctoral dissertation research project will reconstruct the plant community of a lake catchment over the last 7,000 years in order to better understand how tundra ecosystems respond to changing environmental conditions. As the Arctic warms and vegetation ranges are expected to expand northward; the increase in woody vegetation at high latitudes has important implications for both global and northern latitude ecosystems. By identifying how past plant community shifted and by reconstructing temperatures using two new techniques that analyze lake sediments, the doctoral student will enhance understanding about the complexities of the interplay between climate and biogeography at high latitudes both in the past and in a potentially warmer future. The project will provide research education and training opportunities for undergraduate students. As a Doctoral Dissertation Research Improvement award, this award also will provide support to enable a promising doctoral student to establish a strong independent research career.The doctoral student will use a combination of relatively new techniques to analyze past environments. One is the analysis of previously dated lake sediments for sedimentary ancient DNA, the complex mixture of degraded DNA found within bulk sediment, in order to identify the plants that lived within the lake catchment during the Holocene Epoch. The second technique the student will employ is a recently developed biochemical tool, the use of a distribution of a class of bacterial cell membrane lipids called "branched glycerol dialkyl glycerol tetraethers" (brGDGTs) which is able to estimate past temperature. Using these techniques, the student will seek answers to the following sets of research questions: 1) Following the retreat of glaciers, how long did it take for dwarf shrubs to become established in the lake catchment? 2) How did plant diversity respond to the warmth of the early Holocene and cooling during the Late Holocene? 3) When did Betula (dwarf birch), a shrub that likes warmer temperatures currently near its northern limit in this field area, become established, and did it remain present through Holocene temperature fluctuations? Through the use of these new techniques in combination, the project's results will offer new perspectives about the climatic and temporal factors influencing northward plant migration in high northern latitudes.

该博士学位论文研究项目将在过去7000年中重建湖水集水区的植物社区，以更好地了解苔原生态系统如何应对不断变化的环境状况。 随着北极的温暖和植被范围的范围将向北扩展；高纬度的木质植被的增加对全球和北纬生态系统都具有重要意义。 通过确定过去的植物社区的变化以及使用两种分析湖泊沉积物的新技术重建温度，博士生将增强对过去以及过去和潜在温暖的未来的高纬度地区气候和生物地理学之间相互作用的复杂性的理解。 该项目将为本科生提供研究教育和培训机会。 作为博士学位论文研究改进奖，该奖项还将提供支持，使有前途的博士生能够建立强大的独立研究职业。博士生将使用相对较新的技术来分析过去的环境。 一种是对先前约会的湖泊沉积物的分析，用于沉积古代DNA，这是在散装沉积物中发现的降解DNA的复杂混合物，以鉴定在全新世时期内居住在湖水中的植物。 该学生将采用的第二种技术是最近开发的生化工具，即使用一类细菌细胞膜脂质的分布，称为“分支甘油二甲基甘油四核酸酯”（BRGDGTS），能够估算过去的温度。 使用这些技术，学生将寻求以下一组研究问题的答案：1）冰川撤退后，矮灌木在湖水集水区建立需要多长时间？ 2）植物多样性如何应对全新世早期早期和冷却的温暖？ 3）何时betula（矮桦树）是一种喜欢当前在该野外区域北部极限附近温度较高的灌木，建立了，并且是否通过全新世温度的波动仍然存在？ 通过将这些新技术结合起来，该项目的结果将提供有关影响北纬度高纬度北部植物迁移的气候和时间因素的新观点。