Graduate Degree Program in Ecology

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These digital collections include theses, dissertations, faculty publications, photographs, and datasets from the Graduate Degree Program in Ecology.

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Open Access
Culture, water, livelihoods and adaptation in the complex socio-ecological systems of Colorado, U.S.A.
(Colorado State University. Libraries, 2020) Even, Trevor Lee, author; Galvin, Kathleen, advisor; Ojima, Dennis, advisor; Waskom, Reagan, committee member; Boone, Randall, committee member
This dissertation comprises the results of several years of mixed-methods qualitative research on the socio-ecological systems of the U.S. state of Colorado, with a particular focus on their ability to effectively manage natural resource and ecosystem-related challenges amid intensifying social, environmental, and climatic change. Located at the interface of the Great Plains and the Semi-Arid Western U.S., Colorado faces numerous significant challenges from current escalations of climate variability, future trends towards warming temperatures, intensified urban population growth trends, and growing demand for limited water resources. This work, comprised of the results of two distinct but interrelated projects, therefore asks, in the broadest terms, How are key livelihood and cultural systems in the state engaging with critical natural resource and climate-related risks? Taken to a more granular level, it investigates, 1) What are the most vulnerable components of the socio-ecological systems of Colorado in terms of local expressions of climate change and resource management; 2) How are these systems currently engaging with those vulnerabilities on a cultural level, and 3) How can the interdisciplinary scientific community and policy-makers better align themselves to serve their needs for adaptation? In Part I, titled "Changing Weather and Livelihoods in Rural Colorado," I attempt to answer these questions at a state-wide level. Here, I rely upon interviews with ranchers, farmers, recreational sector experts, and extensive secondary data gathering on the varied ways in which sensitive land-based livelihoods in the state have been impacted by drought, wildfire, flooding, extreme precipitation events, and related phenomena over the last two decades, doing so in order to chart out how leaders in these sectors are adapting to changing weather-related risk profiles. In this, I identify significant vulnerabilities within livelihoods central to rural economics and identity, as well as barriers to current and future adaptation efforts in the form of economic, policy, information access, and cross-cultural communication challenges. As part of this, water – both as a resource and as a site of cultural values – emerges as critical to nearly every future-oriented line of inquiry, as the state's physical and socially constructed patterns of water scarcity weave through nearly every aspect of both its vulnerabilities and its capacity to adapt to climate- and ecologically-driven challenges. In Part II, then, I ask, "How can the state's human-altered hydrological systems – i.e., socio-hydrological systems – approach a level of self-understanding that takes into account the wide range of diverse perspectives and livelihoods associated with water systems at the basin scale?" Titled "Conceptualizations and Valuations of Water in the South Platte Basin," it takes a more zoomed-in approach, examining cultures of water commodification, use, interaction, cultural connection, and risk management across six key viewpoints within the Colorado South Platte Basin's complex and multi-layered water management systems. In this, it attempts to bridge existing gaps within the varied literatures related to water resources management and the social-science investigation of human-water system interactions, aiming to advance understanding of how cultural systems within hydrological basins heavily influenced by human intervention influence contemporary and future dynamics of water management and socially-constructed water scarcity. Based on in-depth interviews with water managers, users, advocates, and consultants from around the region as well as a variety of secondary data, it attempts to sketch out a typology of water valuation and understand across four distinct levels of value and across six distinct viewpoints with implications for the water system's current operation and future capacity to adapt to increasing variability and extreme event risk. It finds significant diversity among different types of actor groups involved in the water decision-making systems of the region, as well as numerous innovative avenues toward bridging these gaps in the form of "hybridized" or "nexus" approaches to water infrastructure development, environmental protection, and flood risk mitigation that capitalize upon multiple value orientations as they enact manipulations of the region's water systems. Finally, I discuss several important gaps identified in the region's cultures of water, including the lack of a meaningful system-wide identity, and the lack of affirmative spaces for creatively imagining the future at the basin scale.
Open Access
Factors contributing to the adaptive capacity of South Platte River Basin water providers and implications for regional vulnerability
(Colorado State University. Libraries, 2019) Runyon, Amber N., author; Ojima, Dennis, advisor; Arabi, Mazdak, committee member; Betsill, Michele M., committee member; Boone, Randall B., committee member; McNeeley, Shannon, committee member
To view the abstract, please see the full text of the document.
Open Access
The eco-evolutionary consequences of multiple introductions for colonizing individuals
(Colorado State University. Libraries, 2014) Koontz, Michael, author; Hufbauer, Ruth, advisor; Hobbs, Tom, committee member; Melbourne, Brett, committee member
Predicting the fate of individuals colonizing novel habitats is an elusive but critical goal in fields as diverse as invasion biology, biological control, climate change-induced species range shifts, and reintroductions of rare species. Propagule pressure, which comprises the number of introduction events (propagule number) and the number of individuals per introduction event (propagule size), consistently correlates with a greater probability of population establishment. It is unclear which component, propagule number or propagule size, is more important for establishment, or under what environmental conditions their relative importance may shift. We used 917 independent Tribolium flour beetle populations in a microcosm experiment to disentangle the importance of the different components of propagule pressure. In a factorial design, we held the total number of introduced individuals constant (20) and varied the number of introductions used to distribute them (1, 2, 4, or 5 events) into stable or randomly fluctuating novel environments. Counter to expectations, we found no effect of environmental stability on extinction probability or time to extinction. We also found that several, small introduction events resulted in the lowest extinction probability and the longest time to extinction. We propose that continuing introductions provided low amounts of gene flow that were critical to alleviating inbreeding depression and/or reducing allelic loss by drift in the incipient populations. Our results speak to the importance of preventing future introductions of invasive species (even those that are already established), and using sustained efforts to establish biological control agents or reintroduce desirable organisms to their former range.
Open Access
The potential for adaptation in the model plant, Arabidopsis, and its close relative, Boechera
(Colorado State University. Libraries, 2014) Lovell, John Thomson, author; McKay, John K., advisor; Ghalambor, Cameron K., committee member; Bauerle, William L., committee member; Angert, Amy L., committee member
Populations of a species are found across diverse environments. Frequently, evolutionary responses to varying natural selection pressures across environments cause adaptive differentiation among populations. For plants with limited dispersal capability, adaptation is the primary way populations can persist through changing environments and climates. Therefore, factors that constrain adaptation can directly affect the conservation status and future distributions of species and populations. Contemporary adaptations, via either selection on standing genetic variation or new beneficial mutations that sweep to fixation, have been observed across many taxonomic groups. However, these events of fast, streamlined adaptive evolution may be rare. Instead, adaptation is often constrained by both ecological and genetic forces. Determining the mechanisms and ecological manifestations of adaptive constraint remains a major challenge for evolutionary biologists, conservation biologists and crop breeders. The primary goal of my dissertation research is to address this challenge. The research projects described herein documented the extent and causes of evolutionary constraint by accomplishing three separate goals: (1) to document genes underlying drought adaptation in the model plant, Arabidopsis thaliana, to infer the adaptive effects of pleiotropy, (2) to determine the mechanisms constraining adaptation in rare species relative to widespread congeners, and (3) to assess the degree of adaptive differentiation across the genomic loci and populations. By measuring quantitative and molecular diversity across several species, I determined the relative potential of adaptation at the gene, population, and species levels of organization. In chapter 2 I studied adaptation at the gene-level and demonstrated that the Arabidopsis thaliana gene FRI (FRIGIDA) exhibits adaptive pleiotropy. Through simultaneous genetic effects on many traits, variation at the single gene FRI produces trait correlations along an axis that is in line with the vector of selection. In this case, sequence polymorphism at FRI caused phenotypic co-variance of water-use-efficiency (WUE), relative growth rate and timing of flowering. This genetic correlation coincided with a well-described adaptive correlation found in natural and agricultural systems. In chapter 3, I studied the processes that cause range size diversity across species, by comparing population ecology and genetics of species with broadly divergent range sizes. I assayed the heritability of potentially adaptive traits and other quantitative genetic statistics from multiple rare and widespread species and found that rare species lack heritable genetic variation and physiological plasticity. Combined, these factors place rare species at increased risk of extinction across changing environmental conditions. In chapter 4, I studied adaptation at the population level. I examined how environmental variation impacted genomic structure, selection pressures and local adaptation in Boechera spatifolia (Brassicaceae), a species that contains both sexual and asexual (apomictic) individuals. I found that, despite occupying sympatric sites, apomictic lineages are both phenotypically and genetically distinct from sexuals. Additionally, while sexual populations formed strong clines (both genomic and physiological) along latitude and elevation gradients, apomicts showed no such signature of local adaptation.

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