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The Evolution And Development Of Awns In The Grass Subfamily Pooideae, Erin L. Patterson
The Evolution And Development Of Awns In The Grass Subfamily Pooideae, Erin L. Patterson
Doctoral Dissertations
This research focuses on a specific example of replicated evolution: the grass awn. Awns are typically extensions of the lemma, but may also appear on glumes or paleas. The lemma is a leaf-like organ on the exterior of the grass flower, the glumes are a pair of bracts subtending the basic unit of grass inflorescences, the spikelet, and the palea is the floral organ opposite the lemma. Awns are often described as "hair-" or "bristle-" like, but appear in many different shapes. Many awns are “twisted & geniculate", in which the awn has two sections, a lower twisted column, and …
Constraints Of The Imagination: How Phenotypes Are Shaped Through Genetics, The Environment, And Development, Michelle Gilbert
Constraints Of The Imagination: How Phenotypes Are Shaped Through Genetics, The Environment, And Development, Michelle Gilbert
Doctoral Dissertations
Phenotypic constraints are ubiquitous throughout nature, being found throughout all stages of life and at multiple different biological levels including cellular, genetic, environmental, behavioral, evolutionary, and developmental. These constraints have shaped, not only the natural world, but the way that we perceive what is possible, or impossible, an observation made clear by François Jacob in his 1977 paper “Evolution and Tinkering”. This is reflected in the literature, repeatedly, by the regular occurrence of densely packed visualization of phenotypic space that seemingly always have large areas that go unoccupied. Despite constrained regions of space being observable across countless taxa, identifying the …
Ecology And Phytochemistry Of The Non-Native Plant Thlaspi Arvense (Brassicaceae) In Subalpine Meadows Of Colorado, Usa, Elsa Cousins
Ecology And Phytochemistry Of The Non-Native Plant Thlaspi Arvense (Brassicaceae) In Subalpine Meadows Of Colorado, Usa, Elsa Cousins
Doctoral Dissertations
Climate change is altering ecosystems at multiple scales. Globally, warming temperatures and increasing irregularity of precipitation will have large scale impacts on species distribution and success. Locally, understanding species response to fine scale microhabitat variation can provide key insights into population adaptation. Non-native plants represent an opportunity to investigate population level response and adaptation to relatively novel combinations of biotic and abiotic environments. Subalpine meadows are at the intersection of biotic and abiotic change, as large-scale climatic shifts alter water and temperature regimes and species range shifts become increasingly common and larger in scale. This dissertation addresses these questions of …
Functional Morphology, Biomechanics, And Evolution Of Ruminant Mammals, Abby Vander Linden
Functional Morphology, Biomechanics, And Evolution Of Ruminant Mammals, Abby Vander Linden
Doctoral Dissertations
Ruminant mammals, including the families Bovidae, Cervidae, Tragulidae, Moschidae, Antilocapridae, and Giraffidae, display incredible past and present diversity in morphology, ecology, and behavior. They inhabit an impressive range of environments across North and South America, Europe, Asia, and Africa, and compel the fascination of naturalists and researchers alike with their charismatic social behavior and conspicuous cranial appendages. I explore the drivers and consequences of this spectacular diversity through a comparative morphological framework, biomechanical modeling approaches, and semi-parametric and likelihood-based methods for estimating state-dependent diversification rates across the ruminant phylogeny. Together, these investigations provide evidence for adaptation via correlated evolution of …
Factors Influencing Primate Hair Microbiome Diversity, Catherine Kitrinos
Factors Influencing Primate Hair Microbiome Diversity, Catherine Kitrinos
Masters Theses
Primate hair is both a substrate upon which essential social interactions occur and an important host-pathogen interface. As commensal microbes provide important immune functions for their hosts, understanding the microbial diversity in primate hair could provide insight into primate immunity and disease transmission. While studies of human hair and skin microbiomes show differences in microbial communities across body regions, little is known about the nonhuman primate hair microbiome. In this study, we collected hair samples (n=159) from 8 body regions across 12 nonhuman primate species housed at 3 US institutions to examine 1) the diversity and composition of the primate …
Dynamic Evolution In The Leucine-Rich Repeat Receptor-Like Kinase (Lrr-Rlk) Family Of Receptors, Jarrett Man
Dynamic Evolution In The Leucine-Rich Repeat Receptor-Like Kinase (Lrr-Rlk) Family Of Receptors, Jarrett Man
Doctoral Dissertations
Cells in multicellular organisms must gauge their environmental conditions, including neighboring cells, during development. In plants, the Leucine-Rich Repeat Receptor-like Kinases (LRR-RLKs) encode a family of membrane-bound receptors that transduce such cell-to-cell signals and are required for many aspects of plant development. Very little is known about the function of most of these genes, and the evolutionary history of the family is difficult to infer because of its size and complexity. Several factors contribute to this difficulty, including genetic redundancy, challenging bioinformatic detection, exceptionally large family size, and high copy number variation among species. In this dissertation, I characterize some …
De-Coding The Impact Of Evolved Changes In Gene Expression And Cellular Phenotype On Primate Evolution, Trisha Zintel
De-Coding The Impact Of Evolved Changes In Gene Expression And Cellular Phenotype On Primate Evolution, Trisha Zintel
Doctoral Dissertations
The goal of the dissertation work outlined here was to investigate the influence of proximal processes contributing to evolutionary differences in phenotypes among primate species. There are numerous previous comparative analyses of gene expression between primate brain regions. However, primate brain tissue samples are relatively rare, and my results have contributed to the pre-existing data on more well-studied primates (i.e. humans, chimpanzees, macaques, marmosets) as well as produced information on more rarely-studied primates (i.e. patas monkey, siamang, spider monkey). Additionally, the primary visual cortex has not previously been as extensively studied at the level of gene expression as other brain …
Patterns Of Morphological Plasticity In Metriaclima Zebra And Danio Rerio Suggest Differently Canalized Phenotypes Due To Form-Function Relationships, Dylan Jockel
Masters Theses
In order to ascertain the degree of compatibility in developmental restructuring and behavioral plasticity between two fish species frequently made subject of laboratory research (Metriaclima zebra & Danio rerio), alternative trophic niche exposure experiments utilizing novel three-prong feeding treatments were conducted to obtain morphometric data, which demonstrated both species do bear some degree of plasticity. The results are somewhat complicated by differences in locality of detectable restructuring, which may be due to disparity in the form-function relationship for each species’ lineage. Each is notable in the manner of respective species’ jaw protrusion, as it is driven by anterior …
Impacts Of Genome And Nuclear Architecture On Molecular Evolution In Eukaryotes, Xyrus Maurer-Alcalá
Impacts Of Genome And Nuclear Architecture On Molecular Evolution In Eukaryotes, Xyrus Maurer-Alcalá
Doctoral Dissertations
The traditional view of genomes suggests that they are static entities changing slowly in sequence and structure through time (e.g. evolving over geological time-scales). This outdated view has been challenged as our understanding of the dynamic nature of genomes has increased. Changes in DNA content (i.e. polyploidy) are common to specific life-cycle stages in a variety of eukaryotes, as are changes in genome content itself. These dramatic genomic changes include chromosomal deletions (i.e. paternal chromosome deletion in insects; Goday and Esteban 2001; Ross, et al. 2010), developmentally regulated genome rearrangements (e.g. the V(D)J system in adaptive immunity in mammals; Schatz …
Aggressive Signaling In New World Warblers, David Hof
Aggressive Signaling In New World Warblers, David Hof
Doctoral Dissertations
In many animal species, communication can enable individuals to resolve conflict without the high potential costs involved in direct fighting. During contests, animals may exchange information about their aggressive motivational state. A central question throughout the study of animal communication research has been whether animal signals convey reliable information, and this question has been particularly relevant to communication during conflicts where the evolutionary interests of competitors directly oppose. Deceptive signaling of aggressive motivation would be highly favored by natural selection because it could allow individuals to gain access to resources they might not gain through direct combat. However, selection should …
Loss Of Cell Surface Agal During Catarrhine Evolution: Possible Implications For The Evolution Of Resistance To Viral Infections And For Oligocene Lineage Divergence, Idalia Aracely Rodriguez
Loss Of Cell Surface Agal During Catarrhine Evolution: Possible Implications For The Evolution Of Resistance To Viral Infections And For Oligocene Lineage Divergence, Idalia Aracely Rodriguez
Doctoral Dissertations
The divergence of the two superfamilies belonging to the Infraorder Catarrhini –Cercopithecoidea (Old World monkeys) and Hominoidea (apes, including humans) – is generally assumed to have occurred during the Oligocene, between 38 and 20 million years ago. Genetic studies indicate that this time period was one of active genetic evolution under strong purifying selection for catarrhine primates. This includes selective pressures on the glycoprotein galactosyltransferase 1 (GGTA1) gene and subsequent inactivation “clocked” at approximately 28 ma, possibly prior to the Cercopithecoidea/Hominoidea split. The GGTA1 gene codes for an a1,3 galactosyltransferase (GT) enzyme that synthesizes a terminal disaccharide, …