Date of Award
Open Access Dissertation
Doctor of Philosophy in Biological Sciences (PhD)
Administrative Home Department
Department of Biological Sciences
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Committee Member 2
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Polyploidy (whole genome duplication) is large-scale mutation that increases genome size and alters the genomic expression patterns, thus influencing morphological and physiological traits. Given that polyploids and progenitor diploids can be geographically segregated, and that polyploidy is prevalent in invasive plant taxa, polyploidy might affect the ability to tolerate and adapt to variable and/or novel environments. Responsiveness to soil nitrogen (N) and phosphorus (P) availability are of particular interest because 1) nucleic acids (DNA and RNA) require large amounts of N and P for their biosynthesis, potentially disadvantaging polyploids in nutrient-poor environments; and 2) biological invasions usually begin in urbanized areas with abundant N and P availability. The overall goal of this dissertation was to evaluate how the genomic attributes of genome size and polyploidy independently and concurrently influence tolerance to nutrient availability as a means of better understanding the ecological and evolutionary role of genome size and the preponderance of polyploidy in invasive plants. Throughout a series of greenhouse, potted-field, and RNA sequencing studies using diploid, native-tetraploid, invasive-tetraploid, and hexaploid Solidago gigantea we found that: 1) differences in morphology and physiology between tetraploids and diploids might equate to tetraploids being better competitors, regardless of the abiotic environment; 2) material costs increase with genome size and ploidy level; 3) polyploids exhibit strategies to reduce these material costs; 4) polyploids tended to show more phenotypic plasticity than diploids in the most NP enhanced environments, but plasticity did not differ much between native- and invasive-tetraploids; and 5) tetraploids down-regulate more genes associated with costly traits relative to diploids in low NP conditions, and differences in gene expression between native- and invasive tetraploids was marginal. These studies show that material costs associated with genome size might limit the ecological success of polyploids in nutrient poor conditions, but mechanisms selectively favored to reduce these costs could lessen the selective pressures favoring small genomes. Furthermore, the soil nutrient environment might influence the invasive success of S. gigantea and other polyploid invaders, as anthropogenic-caused nutrient enrichment may create environments that release polyploid invaders from nutrient constraints and allow for enhanced investment into fitness and competitive traits.
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Walczyk, Angela M., "INVESTIGATING THE ROLE OF GENOMIC MATERIAL COSTS IN ECOLOGICAL, EVOLUTIONARY, AND INVASION DYNAMICS USING THE SOLIDAGO GIGANTEA (GIANT GOLDENROD) POLYPLOID COMPLEX", Open Access Dissertation, Michigan Technological University, 2022.