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

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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.