EAR-PF Ancient DNA meets modern genomes: An exploration of diatom evolution, ecology, and environmental change in the Yellowstone Basin

Trisha L Spanbauer博士获得了美国国家科学基金会EAR博士后奖学金，在德克萨斯大学奥斯汀分校开展研究和教育计划。该项目旨在通过使用现代和化石遗传物质来评估微生物的进化和分化。与此同时，本研究还将利用古DNA （aDNA）分析来研究隐藏的浮游植物多样性，并测试大型淡水湖中aDNA的保存情况。这个跨学科的项目结合古生物学的方法来研究形态变化和下一代分子遗传学工具来探索一个最近分化的硅藻物种过去的进化变化。为了让公众参与到该项目的成果中来，德克萨斯大学奥斯汀分校的德克萨斯纪念博物馆将在全年的特殊活动中提供外展服务。该项目的教育目标包括为中学教师提供免费讲习班，为本科生提供学习模块，吸引本科生参与研究，并为高年级本科生提供古生态学和古气候学讲座。黄石湖上的“尼加拉瓜Stephanodiscus niagarae”的前身“Stephanodiscus yellowstonensis”的进化是硅藻物种形成的一个极好的记录案例。本项目将通过对“Stephanodiscus yellowstonensis”瓣膜形态随时间的最大似然建模，并通过aDNA探索遗传进化。同时，这些分析将详细阐述硅藻形态和分子进化的模式和速度。此外，本项目将利用aDNA探索黄石湖中隐藏的浮游植物多样性，并确定aDNA保存和降解的任何问题。前者将有助于扩大对全新世古生态淡水群落的理解，后者将有助于描述aDNA作为环境变化的紧急代理的好处和局限性。这种方法的转换组合允许将微观进化变化与宏观进化结果联系起来。形态进化提供的历史框架将丰富解释新近分化微生物的aDNA的能力。此外，该项目还具有进一步开发aDNA作为古湖泊代用物和分子进化工具的潜力。

Dr. Trisha L Spanbauer has been granted an NSF EAR Postdoctoral Fellowship to carry out research and education plans at the University of Texas at Austin. This project seeks to assess the evolution and differentiation of microorganisms by using modern and fossil genetic material. While doing so, this study will also investigate hidden phytoplankton diversity with ancient DNA (aDNA) analysis and test the preservation of aDNA in large freshwater lakes. This interdisciplinary project combines paleontological methodology to investigate morphological changes with next-generation molecular genetics tools to explore past evolutionary changes in a recently diverged species of diatom. To engage the public in the outcomes of this project, outreach will be provided through the University of Texas at Austin's Texas Memorial Museum at special events throughout the year. The projects educational goals include free workshops for middle school teachers, learning modules for undergraduate classes, engaging undergraduates in the research, and lectures on paleoecology and paleoclimatology for upper-level undergraduate classes.The evolution of "Stephanodiscus yellowstonensis" from a "Stephanodiscus niagarae" predecessor in Yellowstone Lake is an excellent documented case of diatom speciation. This project will investigate the evolution of "Stephanodiscus yellowstonensis" through maximum likelihood modeling of the valve morphology through time, and exploring the genetic evolution through aDNA. In tandem, these analyses will elaborate on the mode and pace of both morphological and molecular evolution in diatoms. In addition, this project will use aDNA to explore hidden phytoplankton diversity in Yellowstone Lake and to determine any issues with the preservation and degradation of aDNA. The former will allow for expanded understanding of the paleoecological freshwater community during the Holocene and the latter will help to delineate the benefits and limitations of aDNA as an emergent proxy of environmental change. This transformational combination of approaches allows for the linking of microevolutionary changes to macroevolutionary outcomes. The historical framework provided by the morphological evolution will enrich the ability to interpret the aDNA of a recently diverged microorganism. Additionally, the proposed project has the potential further develop aDNA as a paleolimnological proxy and molecular evolutionary tool.