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You searched for +publisher:"Colorado State University" +contributor:("Hoke, Kim L."). Showing records 1 – 3 of 3 total matches.

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1. Womack, Molly Corinne. Evolution of 'earlessness' in the true Toad family (Bufonidae), The.

Degree: PhD, Biology, 2016, Colorado State University

Anurans (frogs and toads) have a tympanic middle ear to transmit airborne sound from the environment to their inner ear sensory cells. Yet, many bufonid (true toad) species have independently evolved earlessness, the lack of a tympanic middle ear, despite the importance of acoustic communication in most toad mating systems. My thesis aims to determine why middle ear structures are so evolutionarily labile in the Bufonidae family by comparing development, sensory, and morphological data of eared and earless toads within a phylogenetic context. I show that the middle ear forms very late in the development of toads and takes many months past metamorphosis to become fully functional. Adult earless species are typically less sensitive to high frequency sound and more sensitive to low frequency vibrations compared to eared toads. I also find the skulls of eared and earless are very similar, indicating the middle ear is lost without change to other developmentally or genetically linked skull features. I conclude that alternative hearing pathways allow earless species to retain some hearing sensitivity, and discuss roles for development and behavior in shaping the evolutionary lability of ear structures. Advisors/Committee Members: Hoke, Kim L. (advisor), Davies, Patricia L. (committee member), Mueller, Rachel L. (committee member), Naug, Dhurba (committee member).

Subjects/Keywords: comparative morphology; earless; sensory loss; developmental constraint; anurans; evolutionary development

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APA (6th Edition):

Womack, M. C. (2016). Evolution of 'earlessness' in the true Toad family (Bufonidae), The. (Doctoral Dissertation). Colorado State University. Retrieved from http://hdl.handle.net/10217/178880

Chicago Manual of Style (16th Edition):

Womack, Molly Corinne. “Evolution of 'earlessness' in the true Toad family (Bufonidae), The.” 2016. Doctoral Dissertation, Colorado State University. Accessed January 23, 2021. http://hdl.handle.net/10217/178880.

MLA Handbook (7th Edition):

Womack, Molly Corinne. “Evolution of 'earlessness' in the true Toad family (Bufonidae), The.” 2016. Web. 23 Jan 2021.

Vancouver:

Womack MC. Evolution of 'earlessness' in the true Toad family (Bufonidae), The. [Internet] [Doctoral dissertation]. Colorado State University; 2016. [cited 2021 Jan 23]. Available from: http://hdl.handle.net/10217/178880.

Council of Science Editors:

Womack MC. Evolution of 'earlessness' in the true Toad family (Bufonidae), The. [Doctoral Dissertation]. Colorado State University; 2016. Available from: http://hdl.handle.net/10217/178880


Colorado State University

2. Fischer, Eva Kristin. Flexibility and constraint in the evolution of gene expression and behavior.

Degree: PhD, Biology, 2015, Colorado State University

Our understanding of how underlying molecular, neural, and physiological mechanisms contribute to phenotypic evolvability remains limited. Central to understanding the evolutionary potential of phenotypes is an understanding of the extent to which the mechanisms underlying phenotypic differences are flexible versus constrained. My dissertation takes advantage of the unique evolutionary history of Trinidadian guppies (Poecilia reticulata) to explore patterns of flexibility and constraint at three levels. In the first study of my dissertation, I examined genetic and developmental influences on variation and covariation in a suite of behavioral traits to understand whether correlations among traits constrain adaptation to novel environments. I reared guppies from high- and low-predation source populations in environments with and without predators to mimic native and novel environmental conditions and characterized differences in a suite of 21 behaviors measured in four behavioral assays. I found that behavioral variance and covariance structure were altered in novel environments in a manner that likely shaped subsequent selection. My findings suggest that divergence in a novel environment was not constrained by trait correlations in the native environment, and that plastic changes in covariance structure may in fact influence the form of adaptation. In the second study of my dissertation I examined associations between gene expression (transcriptomic) differences and behavior to understand how underlying transcriptional mechanisms mediate behavioral flexibility across developmental and evolutionary timescales. I reared guppies and assayed behavior as before, and quantified whole-brain gene expression from each individual. My dataset allowed me to relate changes in the expression of single genes and gene networks to behavior across genetic backgrounds and rearing environments. I found that conserved gene networks had flexible relationships with behavior, suggesting that alternative transcriptional solutions may give rise to similar behavioral phenotypes across timescales. I propose that this combination of conservation and flexibility balances phenotypic robustness and evolvability in novel environments. Recent studies have considered whether similar phenotypes also share underlying mechanisms, but data are conflicting. In the third study of my dissertation, I compared gene expression signatures associated with adaptation in two distinct evolutionary lineages to ask whether parallel, independent evolutionary events rely on shared mechanisms. I used transcriptomic approaches to quantify genetic and developmental differences in brain gene expression in two high- and low-predation guppy population pairs that represent distinct evolutionary lineages. I found evidence for both shared and distinct transcriptional mechanisms associated with adaptation. Moreover, I demonstrated that expression differences are more likely to evolve in genes that were highly connected to other genes in a gene network.… Advisors/Committee Members: Hoke, Kim L. (advisor), Ghalambor, Cameron K. (committee member), Hentges, Shane T. (committee member), Mueller, Rachel L. (committee member).

Subjects/Keywords: flexibility; behavior; transcriptomics; neuroethology; Poecilia reticulata

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APA (6th Edition):

Fischer, E. K. (2015). Flexibility and constraint in the evolution of gene expression and behavior. (Doctoral Dissertation). Colorado State University. Retrieved from http://hdl.handle.net/10217/167165

Chicago Manual of Style (16th Edition):

Fischer, Eva Kristin. “Flexibility and constraint in the evolution of gene expression and behavior.” 2015. Doctoral Dissertation, Colorado State University. Accessed January 23, 2021. http://hdl.handle.net/10217/167165.

MLA Handbook (7th Edition):

Fischer, Eva Kristin. “Flexibility and constraint in the evolution of gene expression and behavior.” 2015. Web. 23 Jan 2021.

Vancouver:

Fischer EK. Flexibility and constraint in the evolution of gene expression and behavior. [Internet] [Doctoral dissertation]. Colorado State University; 2015. [cited 2021 Jan 23]. Available from: http://hdl.handle.net/10217/167165.

Council of Science Editors:

Fischer EK. Flexibility and constraint in the evolution of gene expression and behavior. [Doctoral Dissertation]. Colorado State University; 2015. Available from: http://hdl.handle.net/10217/167165

3. Broder, Emily Dale. Evolution and plasticity of Trinidadian guppies in the field, the laboratory, and the classroom.

Degree: PhD, Ecology, 2016, Colorado State University

A fundamental question in evolutionary biology is how organisms respond to new and changing environments. This question also has conservation implications in the face of human induced rapid environmental change, including invasive species, habitat loss, and climate change. In response to new or changing environments, populations may evolve genetic changes across generations, and individuals may also respond via phenotypic plasticity within a generation. We can use experimental methods and model systems to increase our understanding of the way that genes and the environment interact to shape phenotypes. The Trinidadian guppy is a small freshwater fish that exhibits phenotypic plasticity as well as rapid evolution in response to changes in the environment, namely changes in the predator community. We utilized experimental introductions and common garden experiments to investigate plasticity and evolution of cerebral laterality, genitalia, and mating behavior in guppies. Predation pressure is thought to select for a higher degree of cerebral laterality, or consistency in the partitioning of tasks between hemispheres of the brain. However, we found no difference in laterality between populations that evolved with high versus low levels of predation in the wild (Chapter 1). Instead, brothers reared with chemical predator cues were more highly lateralized than their brothers reared without cues, which is likely adaptive plasticity since a higher degree of laterality is associated with enhanced antipredator behavior. This study revealed the important but largely overlooked role of developmental plasticity in shaping cerebral laterality. Next, we took advantage of an experimental introduction of guppies from an environment with many predators to four replicate streams that contained few predators. In only 4-8 guppy generations, males in the introduced populations evolved shorter gonopodia for a given body size compared to the source population with high predation risk (Chapter 2). This suggests that longer gonopodia are advantageous in environments with predators, consistent with the hypothesis that longer genitalia facilitate forced copulations and allow males to circumvent female choice. We also measured male mating behavior using the same experimental introduction. In approximately 8-12 generations, we documented evolutionary changes in several mating behaviors, but these patterns were not consistent across populations (Chapter 3). We also found that low food levels during development reduced mating effort, but we found no evidence of developmental plasticity in response to predator cues in the rearing environment. Instead, we found an important role for contextual plasticity, a reversible and rapid response to the current situation, evident in behavioral changes with acute chemical cues of predation. Contextual plasticity is though to be especially important for behavioral traits allowing flexibility in response to rapidly changing conditions. This represents one of the few empirical studies designed to explore… Advisors/Committee Members: Angeloni, Lisa M. (advisor), Ghalambor, Cameron K. (committee member), Hoke, Kim L. (committee member), Whittemyer, George (committee member).

Subjects/Keywords: guppy; evolution; plasticity

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Broder, E. D. (2016). Evolution and plasticity of Trinidadian guppies in the field, the laboratory, and the classroom. (Doctoral Dissertation). Colorado State University. Retrieved from http://hdl.handle.net/10217/178923

Chicago Manual of Style (16th Edition):

Broder, Emily Dale. “Evolution and plasticity of Trinidadian guppies in the field, the laboratory, and the classroom.” 2016. Doctoral Dissertation, Colorado State University. Accessed January 23, 2021. http://hdl.handle.net/10217/178923.

MLA Handbook (7th Edition):

Broder, Emily Dale. “Evolution and plasticity of Trinidadian guppies in the field, the laboratory, and the classroom.” 2016. Web. 23 Jan 2021.

Vancouver:

Broder ED. Evolution and plasticity of Trinidadian guppies in the field, the laboratory, and the classroom. [Internet] [Doctoral dissertation]. Colorado State University; 2016. [cited 2021 Jan 23]. Available from: http://hdl.handle.net/10217/178923.

Council of Science Editors:

Broder ED. Evolution and plasticity of Trinidadian guppies in the field, the laboratory, and the classroom. [Doctoral Dissertation]. Colorado State University; 2016. Available from: http://hdl.handle.net/10217/178923

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