Theses and Dissertations
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Browsing Theses and Dissertations by Author "Angeloni, Lisa M., committee member"
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Item Open Access Immunogenicity against a vaccinia virus-vectored oral plague vaccine in black-footed ferrets (Mustela nigripes)(Colorado State University. Libraries, 2020) McCuen, Deborah Grossblat, author; Antolin, Michael F., advisor; Miller, Michael W., advisor; Angeloni, Lisa M., committee member; Schenkel, Alan R., committee member; Schountz, Tony A., committee memberBlack-footed ferrets (Mustela nigripes) are one of the most endangered mammals in North America, in part because they suffer high mortality when infected by plague, caused by the bacterium Yersinia pestis. An injectable plague vaccine is effective in black-footed ferrets but protecting wild ferrets is laborious because of the need to capture and handle these animals. In contrast, an orally delivered vaccine could be more easily distributed, as is the case with the Yersinia Pestis Vaccine that effectively protects the ferrets' main prey, prairie dogs. We evaluated in black-footed ferrets the immunogenicity of an oral vaccinia virus vectored plague vaccine, previously shown to be protective in laboratory mice. We compared antibody response of the oral vaccine to the injectable plague vaccine. Although the oral vaccine appears to be safe in ferrets, lateral flow results indicated an absence of measurable antibody response to plague antigens. Furthermore, a plaque reduction neutralization test revealed that black-footed ferrets have some ability to neutralize vaccinia virus, even without delivery of the oral vaccine or any known exposure to orthopoxvirus. We also investigated if maternal antibody to plague antigens could be detected in ferret kits aged between 39 and 50 days, but results were largely negative. Blood samples of sufficient volume were difficult to obtain from kits and may have contributed to negative results. Based on our findings, it is unlikely that orthopoxvirus-based vaccines will protect captive black-footed ferrets, and other oral plague vaccines should be considered in future research.Item Open Access Testing the effects of gene flow on adaptation, fitness, and demography in wild populations(Colorado State University. Libraries, 2015) Fitzpatrick, Sarah Warner, author; Funk, W. Chris, advisor; Angeloni, Lisa M., committee member; Angert, Amy L., committee member; Bailey, Larissa L., committee member; Ghalambor, Cameron K., committee memberGene flow should reduce differences among populations, potentially limiting adaptation and population growth. But small populations stand to benefit from gene flow through genetic and demographic factors such as heterosis, added genetic variation, and the contribution of immigrants. Understanding the consequences of gene flow is a longstanding and unresolved challenge in evolutionary biology with important implications for conservation of biodiversity. My dissertation research addresses the importance of gene flow from evolutionary and conservation perspectives. In the first study of my dissertation I characterized natural patterns of gene flow and genetic diversity among remaining populations of Arkansas darters (Etheostoma cragini) in Colorado, an endemic to drying streams of the Great Plains, and a candidate for listing under the US Endangered Species Act. I found low diversity and high isolation, especially among sites with low water availability, highlighting this as a species that might eventually benefit from a well-managed manipulation of gene flow. I then turned to the Trinidadian guppy system to test the effects of gene flow using a model species for studying evolution in natural populations. My work capitalized on a series of introduction experiments that led to gene flow from an originally divergent population into native recipient populations. I was able to characterize neutral genetic variation, phenotypic variation, and population size in two native populations before the onset of gene flow. The goal of my first study using this system was to evaluate the level of gene flow and phenotypic divergence at multiple sites downstream from six introduction sites. I found that traits generally matched expectations for local adaptation despite extensive homogenization by gene flow at neutral loci, suggesting that high gene flow does not necessarily overwhelm selection. I followed up on this study by measuring many of the same traits in a common garden environment before and after gene flow to test whether gene flow caused genetically based changes in traits, and to evaluate the commonly held 'gene flow constrains divergence' hypothesis versus the 'divergence in the face of gene flow' hypothesis. I found that gene flow caused most traits to evolve, but whether those changes constrained adaptation depended on initial conditions of the recipient population. Finally, to link gene flow to changes in fitness and demography I conducted a large-scale capture-mark-recapture survey of two native populations beginning three months prior and following 26 months after upstream introductions took place. I genotyped all individuals from the first 17 months of this study to compare the relative fitness (survival and population growth rate) of native, immigrant, and hybrid guppies. In total this survey spanned 8-10 guppy generations and documented substantial increases in genetic variation and population size that could be attributed to gene flow from the introduction site. As a whole, the results from my research suggest that gene flow, even from a divergent population, can provide major demographic benefits to small populations, without necessarily diminishing locally important traits.