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Theses/Dissertations

2013

Evolution

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Full-Text Articles in Life Sciences

The Genetic Architecture And Evolution Of Brain Cortical Folding In A Pedigreed Primate Population, Elizabeth Grace Atkinson Dec 2013

The Genetic Architecture And Evolution Of Brain Cortical Folding In A Pedigreed Primate Population, Elizabeth Grace Atkinson

Arts & Sciences Electronic Theses and Dissertations

Elevated neurological faculty, related to the dramatic increase in brain volume, is a hallmark of the primates. Cognitive capacity, the processing power and speed of the brain, is directly related to the number of neurons in the cerebral cortex and the connectivity network underlying information processing in the brain. Increased cortical folding (gyrification) allows for more neurons to be contained within the volume of the braincase and the arrangement of folds and ridges across the cerebral cortex is an indication of the underlying neural network connecting regions. The goal of this dissertation is to develop a better understanding of the ...


The Evolution And Expression Of Drosophila Meiosis Genes, Danielle Jeanine Beekman Dec 2013

The Evolution And Expression Of Drosophila Meiosis Genes, Danielle Jeanine Beekman

Theses and Dissertations

Drosophila melanogaster is unique amongst model organisms in that males utilize achiasmatic meiosis, where formation of the synaptonemal complex (SC) and recombination are absent. Most organisms require the SC and chiasmata for the successful completion of meiosis and production of viable gametes, making D. melanogaster an ideal system for the study of meiotic variation. The goal of my research was to examine in detail the origin and evolution of male achiasmatic meiosis in Diptera. This was done in three parts: 1) assessing the presence and absence of meiosis genes across dipteran species, 2) analyzing the rate of evolution of Drosophila ...


Microrna Regulation Of Central Nervous System Development And Their Species-Specific Role In Evolution, Hayley Sarah Mcloughlin Dec 2013

Microrna Regulation Of Central Nervous System Development And Their Species-Specific Role In Evolution, Hayley Sarah Mcloughlin

Theses and Dissertations

Genetic dissection of loci important in the control of neurogenesis has improved our understanding of both the evolutionarily conserved and divergent processes in neurodevelopment. These loci include not only protein coding genes [1, 2], but also noncoding RNAs [3-5]. One important family of non-coding RNAs is miRNAs, which control gene expression fundamental in developmental regulation and mature cell maintenance [3, 5-9].

Here, we will first focus our efforts by surveying miRNA regulation in the developing brain. We hypothesize a strong regulatory role of miRNAs during proliferation, cell death, migration and differentiation in the developing mammalian forebrain that has yet to ...


The City In Mind: Environmental Literacy And Adaptation In Nineteenth-Century British Literature, Adam Edward Watkins Oct 2013

The City In Mind: Environmental Literacy And Adaptation In Nineteenth-Century British Literature, Adam Edward Watkins

Open Access Dissertations

This dissertation argues that a new paradigm of selfhood emerged in nineteenth-century British literature, one that recognized the individual will and environmental influence not as antithetical but as dialectical forces in the formation of the self. The concept of an externally negotiated subject challenges both the inward and socially determined conceptions of self that have dominated the relevant criticism. Informed by empiricist, associationist, and evolutionary theories of the mind, the portrayals of subject-formation in this study highlight the radical changes occurring in the human environment in nineteenth-century, which catalyzed the conception of a malleable yet self-forming subject. Along with the ...


Functional Analysis Of Corazonin And Its Receptor In Drosophila Melanogaster, Kai Sha Aug 2013

Functional Analysis Of Corazonin And Its Receptor In Drosophila Melanogaster, Kai Sha

Doctoral Dissertations

Corazonin (Crz) is an amidated undecapeptide originally isolated from the American cockroach. It has been shown to affect diverse physiological functions in a species-specific manner. However, the functionality of Crz in Drosophila melanogaster has not yet been determined. To gain insight into the role of Crz signaling in vivo, Crz and CrzR null alleles were obtained by transposable element mobilization. Flies carrying a deficiency uncovering Crz and pr-set7 loci were generated via P-element excision, and the latter was rescued by wild-type pr-set7 transgene. A mutation of Crz receptor (CrzR) was generated by Minos-element mobilization from GRHRIIMB00583 ...


Characterization Of Phycoerythrin Physiology In Low-Light Adapted Prochlorococcus Ecotypes, Kathryn H. Roache-Johnson Aug 2013

Characterization Of Phycoerythrin Physiology In Low-Light Adapted Prochlorococcus Ecotypes, Kathryn H. Roache-Johnson

Electronic Theses and Dissertations

The marine cyanobacteria Prochlorococcus and Synechococcus are the most abundant phototrophs in the oceans. They cohabit the oligotrophic ocean and thus have coevolved together, yet they have distinctly different methods for harvesting light. Synechococcus, like other cyanobacteria, possess phycobilisomes with various combinations of phycobiliproteins to capture wavelengths of light not otherwise available to chlorophyll. Prochlorococcus lack phycobilisomes and use divinyl chlorophyll b (Chl b2) as their primary accessory pigment to divinyl chlorophyll a (Chl a2) to capture light energy. In addition to the divinyl chlorophylls, Prochlorococcus has genes associated with the phycobiliprotein phycoerythrin (PE), the role of which is still ...


Impact Of Self-Fertilization On Fecundity, The Timing Of First Reproduction, And Population Genetic Structure: Is A Mate Worth The Wait?, Serena Caplins Jun 2013

Impact Of Self-Fertilization On Fecundity, The Timing Of First Reproduction, And Population Genetic Structure: Is A Mate Worth The Wait?, Serena Caplins

Theses and Dissertations

Organisms capable of self-fertilization typically exhibit two evolutionary syndromes uniting high inbreeding depression with low levels of selfing, or low inbreeding depression and high levels of selfing. This study tests for inbreeding depression in an apparent self-compatible, hermaphroditic marine nemertean worm, Prosorhochmus americanus. Fecundity and timing to first reproduction were assessed in isolated and paired worms. Isolated worms produced significantly more offspring than paired worms and did not show inbreeding avoidance. The selfing rate of natural populations was evaluated using species-specific microsatellites and is consistent with preferential selfing (mean: 0.801), though some outcrossing appears to take place. Population genetic ...


The Effects Of Starvation Selection On Drosophila Melanogaster Life History And Development, Lauren A. Reynolds May 2013

The Effects Of Starvation Selection On Drosophila Melanogaster Life History And Development, Lauren A. Reynolds

UNLV Theses, Dissertations, Professional Papers, and Capstones

In nature, animals may endure periods of famine to complete their life cycles. Starvation stress will increase in populations as climates around the world change. To predict how populations may respond to such a stress, laboratory experimentation becomes essential. The evolutionary process of adaptation, its innovations and their trade-offs, can be studied in populations experiencing starvation stress. For this purpose outbred populations ofDrosophila melanogasterwere selected for starvation resistance in the laboratory.

After 60+ generations of starvation selection the starvation-selected flies have gone from surviving 2-3 days without food to 12-14 days without food. How this amazing feat of resistance is ...


Integrating, Developing, And Testing Methods To Generate More Cohesive Approaches To Biogeographic Inference, Mallory Elizabeth Eckstut May 2013

Integrating, Developing, And Testing Methods To Generate More Cohesive Approaches To Biogeographic Inference, Mallory Elizabeth Eckstut

UNLV Theses, Dissertations, Professional Papers, and Capstones

As a fundamental component of the developing discipline of conservation biogeography, broadscale analyses of biotic assembly and disassembly across multiple temporal and spatial scales provide an enhanced understanding of how geologic transformations and climate oscillations have shaped extant patterns of biodiversity. As with any scientific field, there are limitations in the case of biogeographic historical reconstructions. Historical reconstructions are only as robust as the theoretical underpinnings of the methods of reconstruction (including data collection, quality, analysis, and interpretation). Nevertheless, historical reconstructions of species distributions can help inform our understanding of how species respond to environmental change.

My dissertation takes a ...


Understanding Biodiversity: The Importance Of Sexual Dimorphism In The Micro- And Macroevolution Of Hummingbirds, Chelsea Marie Berns Jan 2013

Understanding Biodiversity: The Importance Of Sexual Dimorphism In The Micro- And Macroevolution Of Hummingbirds, Chelsea Marie Berns

Graduate Theses and Dissertations

ABSTRACT

For centuries, biologists have asked "why are there so many species, and why do we see such magnificent biological diversity?" This dissertation addresses this question by examining sexual size and shape dimorphism hummingbird bills at both a micro and macroevolutionary scale. Specifically, I quantify sexual size and shape dimorphism of bill morphology of 269 species of hummingbirds and begin with a species-level study to find that community structure might be a driving factor in the evolution of sexual size dimorphism in 2 sister species of hummingbirds, and the presence of sexual shape dimorphism in one of those species.

I ...


Structure, Dynamics, And Evolution Of The Intrinsically Disordered P53 Transactivation Domain, Wade Michael Borcherds Jan 2013

Structure, Dynamics, And Evolution Of The Intrinsically Disordered P53 Transactivation Domain, Wade Michael Borcherds

Graduate Theses and Dissertations

in numerous disease states, including cancers and neurodegenerative diseases. All proteins are dynamic in nature, occupying a range of conformational flexibilities. This inherent flexibility is required for their function, with ordered proteins and IDPs representing the least flexible, and most flexible, respectively. As such IDPs possess little to no stable tertiary or secondary structure, they instead form broad ensembles of heterogeneous structures, which fluctuate over multiple time scales. Although IDPs often lack stable secondary structure they can assume a more stable structure in the presence of their binding partners in a coupled folding binding reaction.

The phenomenon of the dynamic ...


Complete Genome Sequences And Phylogeny Of West Nile Virus Isolates From Southeastern United States, 2003-2012, Crystal Wedin Jan 2013

Complete Genome Sequences And Phylogeny Of West Nile Virus Isolates From Southeastern United States, 2003-2012, Crystal Wedin

Graduate Theses and Dissertations

The study of the evolution and phylogeny of West Nile virus (WNV) has been an important area of research since the introduction of WNV in 1999. However, genome sequencing of isolates from the Southeastern part of the United States has been somewhat limited. To determine how WNV has evolved at a more localized level, ten isolates from Florida and Georgia from 2003-2012 were completely sequenced using Illumina's next-generation technology. In addition, a phylogenetic comparison of both the complete genome and select partial genomes was completed to ensure consistency among the results. This study further demonstrated the dominance of the ...


The Molecular Basis For Amino-Terminal Acetylation By Nat Proteins, Glen Liszczak Jan 2013

The Molecular Basis For Amino-Terminal Acetylation By Nat Proteins, Glen Liszczak

Publicly Accessible Penn Dissertations

Amino-terminal acetylation is a co-translational process that occurs on a majority of all eukaryotic proteins. This modification mediates a wide range of biological processes including but not limited to cellular apoptosis, enzyme regulation, protein localization and the N-end rule for protein degradation. The amino-terminal acetyltransferase (NAT) enzymes that catalyze this reaction are distinguished from one another on the basis of substrate specificity, which is dictated by the identity of the amino-terminal sequence of the substrate protein. The NatA complex harbors the greatest diversity for substrate selection and is responsible for acetylating a majority of all proteins that undergo this modification ...


Investigating The Evolution Of Cytochromes P450 Involved In Ga Biosynthesis, Sibongile Mafu Jan 2013

Investigating The Evolution Of Cytochromes P450 Involved In Ga Biosynthesis, Sibongile Mafu

Graduate Theses and Dissertations

Vascular plants invariably contain a class II diterpene cyclase (EC 5.5.1.x), as an ent-copalyl diphosphate synthase is required for gibberellin phytohormone biosynthesis. This has provided the basis for evolution of a functionally diverse enzymatic family. A bifunctional diterpene synthase was characterized from the lycophyte Selaginella moellendorffii . The structure of its product, labda-7,13E-dien-15-ol, demonstrates that this enzyme catalyzes a novel class II diterpene cyclization reaction, and clarifies the biosynthetic origins of the family of derived natural products.

All higher plants contain kaurene oxidases (KO), which are multifunctional cytochromes P450 that catalyze oxidation at the C4α methyl, converting ...


The Phylogenetics Of Tachinidae (Insecta: Diptera) With An Emphasis On Subfamily Structure, Daniel J. Davis Jan 2013

The Phylogenetics Of Tachinidae (Insecta: Diptera) With An Emphasis On Subfamily Structure, Daniel J. Davis

Browse all Theses and Dissertations

The parasitoid flies of the Tachinidae family are an important and diverse (>10,000 species) lineage of insects. However, tachinids are not well studied partially due to their confusing classification and taxonomy. DNA sequences were obtained from twenty tribal representatives of Tachinidae, along with eight outgroups in order to phylogenetically reconstruct the superfamilial, subfamilial and tribal relationships of Tachinidae. Seven gene regions of six genes (18S, 28S, COI, CAD, Ef1a, and TPI) were sequenced for each taxon (6214 bp total). Both maximum likelihood and Bayesian methods were used to infer phylogenies. The Sarcophagidae and Oestridae were usually reconstructed as monophyletic ...