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Browsing by Author "Funk, Chris, committee member"

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    Evolution at the edge: how hibernation, heat waves, and hybridization impact a range expansion
    (Colorado State University. Libraries, 2024) Clark, Eliza, author; Hufbauer, Ruth, advisor; Bitume, Ellyn, committee member; Norton, Andrew, committee member; Funk, Chris, committee member
    Evolutionary processes shape the diversity of life on earth. Over millennia, species diverge from one another, radiating out into the tree of life. The same processes of evolution are also acting in much shorter periods of time, selecting for traits, mixing genes across populations, and generating new mutations each generation. These rapid evolutionary processes interact with ecological processes, which are happening on similar time scales. Range expansions, or expansions of a population's geographic distribution, were once considered strictly ecological processes of populations interacting with other populations and the environment, unaffected by evolution. However, modern theory understands range expansions to be crucibles of rapid evolution. Rapid evolution shapes the process of range expansion itself, and is also integral to determining the outcomes of range expansion. During range expansions, ecological and evolutionary processes intertwine, combining to shape the dynamics of a range expansion, like where a population can establish, and how quickly the expansion moves. The study of evolution during range expansions has only just begun to make it out of the theory to be tested in wild populations in nature, so we don't yet know how common evolution during range expansion is, or how large its effects might be. Here, I explore how evolution impacts range expansions that are current and ongoing in natural systems in the wild. I focus on the tamarisk beetle (Diorhabda spp.), deliberately introduced in the United States about two decades ago for biological control of a widespread invasive weed. Through its role as a biological control agent, the tamarisk beetle has expanded its range hundreds of kilometers along rivers, colonizing new areas of the invasive weed in environments very different from its original release habitat. The range expansion of the tamarisk beetle provides a unique opportunity to study evolution during an ongoing natural range expansion across an environmental gradient. Through the following four chapters, I document evolution of dispersal ability and life history traits (Chapter 1), evolution of seasonal dormancy and genetic variation of that trait (Chapter 2), evolution of phenotypic plasticity (Chapter 3), and the impacts of hybridization (Chapter 4). Throughout, I discuss the implications for biological control and the tamarisk beetle specifically, and more generally how these results improve our understanding of how evolution is caused by, enables, and alters natural range expansions over short time periods, even in natural range expansions.
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    Genomics-informed conservation units reveal spatial variation in climate vulnerability in a migratory bird
    (Colorado State University. Libraries, 2023) Miller, Caitlin Vanessa, author; Ruegg, Kristen, advisor; Funk, Chris, committee member; Horton, Kyle, committee member
    Identifying conservation units (CUs) in threatened species is critical for the preservation of adaptive capacity and evolutionary potential in the face of climate change. However, delineating CUs in highly mobile species remains a challenge due to high rates of gene flow and genetic signatures of isolation by distance. If CUs are delineated in highly mobile species, the CUs often lack key biological information about what populations have the most conservation need to guide management decisions. Here we implement a framework for rigorous CU identification in the Canada Warbler (Cardellina canadensis), a high-dispersal migratory bird species of conservation concern, and then integrate demographic modeling and genomic offset within a CU framework to guide conservation decisions. We find that whole-genome structure in this highly mobile species is primarily driven by putative adaptive variation. Identification of CUs across the breeding range revealed that Canada Warblers fall into two Evolutionary Significant Units (ESU), with three putative Adaptive Units (AUs) in the South, East and Northwest. Quantification of genomic offset within each AU reveals significant spatial variation in climate vulnerability, with the Northwestern AU being identified as the most vulnerable to future climate change. Alternatively, quantification of past population trends within each AU revealed the steepest population declines have occurred within the Eastern AU. Overall, we illustrate that genomics-informed CUs provide a strong foundation for identifying current and potential future region-specific threats that can be used to manage highly mobile species in a rapidly changing world.
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    Investigating factors influencing the probability of survival to metamorphosis of boreal toads at multiple scales
    (Colorado State University. Libraries, 2019) Crockett, John, author; Bailey, Larissa, advisor; Muths, Erin, committee member; Funk, Chris, committee member; Huyvaert, Kathryn, committee member
    To view the abstract, please see the full text of the document.
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    Investigating the direct and indirect effects of introduced greenback cutthroat trout on boreal toad recruitment
    (Colorado State University. Libraries, 2015) Lanier, Wendy Elizabeth, author; Bailey, Larissa, advisor; Bestgen, Kevin, committee member; Funk, Chris, committee member
    To view the abstract, please see the full text of the document.
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    Manipulation of resource allocation to increase fecundity in Mimulus gemmiparus
    (Colorado State University. Libraries, 2016) Chu, Kevin, author; Steingraeber, David, advisor; Funk, Chris, committee member; Hufbauer, Ruth, committee member
    Mimulus gemmiparus W. A. Weber, a Colorado endemic, is a rare species that is at risk of becoming endangered. Reproduction in M. gemmiparus is solely by vegetative propagules (bulbils), which function analogously to seeds; sexual reproduction has not been observed in the wild. Manipulation of resource allocation in this plant may shift resources allocated for sexual reproduction to vegetative growth; the investment in increased vegetative growth should result in a direct increase in fecundity. Two experiments were conducted to examine the effects of redistribution of resources and change in meristem fate. The first experiment used plants grown in greenhouse conditions; seemingly nonfunctional floral buds or floral buds and shoot apical meristems were removed to potentially increase bulbil production. The second experiment used plants grown indoors under growing lamps to produce plants that were similar in size to those found in their natural habitats; their shoot apical meristems were removed to potentially induce branching and thus increase vegetative growth to increase bulbil production. Removal of floral buds or removal of both floral buds and shoot apical meristems in a greenhouse environment doubled the number of bulbils produced per plant, increased by approximately two-thirds the total bulbil biomass per plant, increased the ratio of bulbil count to stem biomass, and increased the ratio of bulbil biomass to stem biomass; however, there was a trade-off between having greater number of bulbils and individual bulbil biomass. Solely removing the shoot apical meristem in a low-light environment had no effect on bulbil production; although branching was induced, the primary branches remained small and did not elongate. Secondary branches were formed only on plants that had their shoot apical meristem removed. The total numbers of shoot axes per plant were not significantly different between the control and treatment group; the induction of branching seemingly produces a compensatory effect, but not overcompensation for the removal of the shoot apical meristem. In both experiments, stem biomass did not differ between the control and treatment group(s). Lighting condition in the environment the plants grew in had the greatest effect on stem development, and manipulation of meristems to form new shoots did not increase plant size. Bulbil yield may be increased in greenhouse conditions by manipulation of allocation from sexual reproduction to vegetative growth.
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    Phenotype to genotype and back in emerging and established crop species
    (Colorado State University. Libraries, 2023) Woods, Patrick O'Neal David, author; McKay, John, advisor; Hufbauer, Ruth, committee member; Funk, Chris, committee member; Sloan, Dan, committee member
    Understanding the relationship between the phenotype and genotype is a fundamental goal of genetics. Through the years, two primary approaches have been developed for studying the phenotype-genotype relationship: forward genetic and reverse genetics. Forward genetics enables the potential discovery of numerous candidate genes controlling a phenotype while reverse genetics allows for the mechanistic validation of a single gene's role in controlling a phenotype. Applying these two approaches to crops enables the discovery of genetic targets that can be used for crop improvement through breeding. In this dissertation, I focused on understanding the phenotype-genotype relationship in both the emerging crop Cannabis sativa and the established crop Maize. In Chapter 1, I used both a forward a reverse genetics approach to identify and validate candidate genes controlling agriculturally important traits (agronomic and biochemical) in Cannabis sativa. In Chapter 2, I used a reverse population genetics approach to identify the genetics underlying local adaptation in feral and domesticated populations of Cannabis sativa. In Chapter 3, I used a forward genetics approach to identify candidate genes controlling variation in root system architecture in Maize. Collectively, this work demonstrates how modern genomic techniques can be applied to both new and old crop systems to identify genetic targets for use in crop innovation through breeding.