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Dimensions of diversity in dominant prairie grasses

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dc.contributor.authorHoffman, Ava Marie, author
dc.contributor.authorSmith, Melinda D., advisor
dc.contributor.authorArgueso, Cristiana T., committee member
dc.contributor.authorMcKay, John K., committee member
dc.contributor.authorOcheltree, Troy W., committee member
dc.date.accessioned2019-06-14T17:05:26Z
dc.date.available2020-06-10T17:05:25Z
dc.date.issued2019
dc.description.abstractAs anthropogenic influences cause climate change to worsen, extreme events such as droughts and heat waves are expected to become more frequent. The native prairies of the Central United States have historically experienced drought, yet continue to support highly productive grassland communities. Dominant species in these grasslands, such as Andropogon gerardii in the tallgrass prairie and Bouteloua gracilis in the shortgrass steppe, are drivers of productivity in these ecosystems. Thus, it is necessary to quantify diversity within these key species in order to determine how these important grasses have been historically shaped as well as how they will respond to future climate change. This dissertation seeks to answer (1) How do functionally similar coexisting dominant grasses differ at the molecular level?, (2) How does plasticity contribute to intraspecific diversity?, and (3) how does intraspecific diversity vary across the range of one of these less studied grasses? To determine transcriptional differences between codominant species A. gerardii and Sorghastrum nutans, I performed RNA-seq on watered and droughted tissues, building both species' transcriptomes using Trinity. These codominant grasses responded differently; specifically, A. gerardii had greater regulation of stress alleviation transcripts while S. nutans tended to be more sensitive within 10 key gene-groups related to stress and abscisic acid. These results support previous work on the physiological level, and demonstrate functional diversity at the gene level within dominant species in the tallgrass prairie. To explore this community further, I documented variation in plastic traits across a gradient of water availability in three A. gerardii genotypes. I found that plasticity, in particular nonlinear plasticity, in morphological and physiological traits was widespread and differed across genotypes, highlighting the influence of relatively small changes in water availability on intraspecific diversity. These genotypes also differed in reproductive strategy (flowering versus clonal tillering), but all recovered from drought similarly. These results demonstrated that variation in plasticity patterns may help explain intraspecific diversity and patterns of selection within a population. Differences in drought response strategy, particularly in terms of transcription and plasticity diversity, could provide further niche space by which the tallgrass prairie community can mitigate the effects of future drought. Lastly, I applied an understanding of dominant species diversity in A. gerardii to the relatively understudied dominant dry steppe species B. gracilis. I performed 2b-RAD genome se- quencing and a common garden trait and plasticity analysis across both regionally and locally distributed sites to broadly assess intraspecific diversity in this ecologically and economically important species. I found substantial intraspecific diversity among sites, specifically showing that New Mexico sites were distinct in terms of biomass trait distributions and plasticity. While New Mexico sites were clearly different, all sites were at least somewhat distinct genetically, indicating some limitations to gene flow. As has been shown in A. gerardii, comprehensive analysis of intraspecific diversity in this dominant grass will help clarify mechanisms of ecosystem function as well as conservation and management of the shortgrass steppe ecosystem. Overall, these three projects highlight dimensions of diversity in dominant prairie grasses, providing useful information for predicting how these species and their associated communities are likely to respond to changing climate.
dc.format.mediumborn digital
dc.format.mediumdoctoral dissertations
dc.identifierHoffman_colostate_0053A_15303.pdf
dc.identifier.urihttps://hdl.handle.net/10217/195268
dc.languageEnglish
dc.language.isoeng
dc.publisherColorado State University. Libraries
dc.relation.ispartof2000-2019
dc.rightsCopyright and other restrictions may apply. User is responsible for compliance with all applicable laws. For information about copyright law, please see https://libguides.colostate.edu/copyright.
dc.titleDimensions of diversity in dominant prairie grasses
dc.typeText
dcterms.embargo.expires2020-06-10
dcterms.embargo.terms2020-06-10
dcterms.rights.dplaThis Item is protected by copyright and/or related rights (https://rightsstatements.org/vocab/InC/1.0/). You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s).
thesis.degree.disciplineEcology
thesis.degree.grantorColorado State University
thesis.degree.levelDoctoral
thesis.degree.nameDoctor of Philosophy (Ph.D.)

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