Browsing by Subject "morphology"

Now showing 1 - 10 of 10
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    Contulma paluguillensis (Trichoptera:Anomalopsychidae), a new caddisfly from the high Andes of Ecuador, and its natural history
    (University of Chicago Press, 2012) Holzenthal, Ralph W.; Rios-Touma, Blanca
    Adults and larvae of a new species of Contulma Flint (Trichoptera:Anomalopsychidae) are described from Ecuador. The new species is similar to Contulma papallacta Holzenthal and Flint, but differs in having shorter, less spatulate dorsolateral processes and shorter setose lateral processes of segment IX in the male genitalia. Monthly Hess, sticky trap, and emergence-trap collections indicated that the new species is uncommon, probably univoltine, but with continuous larval growth and extended adult emergence, and has algivorous larvae.
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    From individuals to species: how natural selection and phenotypic plasticity shape ecomorphological evolution in freshwater mussels
    (2023-05) Keogh, Sean
    Adaptation is the hallmark of evolutionary biology, explaining how species achieve ecological success through natural selection. However, adaptation is challenging to identify leading to frequent ‘just-so stories’ to explain the adaptive features of organisms. At the core of adaptive studies is the motivation to find the fit between morphological and functional diversity. Here I used the freshwater mussels of North America as a study system to investigate the fit between morphological and ecological traits both within and across species. I used comparative and experimental inferences to identify the evolutionary mechanisms driving ecomorphological patterns. My first chapter identified ecomorphological patterns within and across species between shell thickness, shell anterior thickening, and flow rate. Across species, I found widespread convergence in these traits showing that natural selection produces the following adaptations to riverine flow rates: thick and anteriorly thickened shells in high flow rates (likely for stability in the substratum) and thin and uniformly thickened shells in low flow rates (likely for burrowing efficiency). Additionally, within species, I found a creditably positive relationship between shell thickness and flow rate, effectively mirroring interspecific relationships albeit at different scales. Intraspecific processes may therefore be partially responsible for the evolvability and ecological diversification of the clade. Although I identified this intraspecific ecomorphological pattern, I could not identify the mechanism producing this pattern. To address this, in my second chapter I conducted a common garden experiment on a morphologically variable species, Pyganodon grandis. The morphology of this species varies predictably between lake and stream environments and I investigated if this relationship was due to phenotypic plasticity or genetic differentiation. By rearing siblings from a single female’s broodstock, I minimized genetic variation, and released ~6,000 marked individuals into nine sites (four streams, five lakes). Two years after release, I recaptured a total of 70 individuals from both stream and lake sites showing significant shell shape differences between habitats and no shell shape differences between recaptured siblings and wild P. grandis reared at the same site, showing definitively that phenotypic plasticity rather than genetic differentiation is driving ecomorphological patterns. In my third and final chapter I ran a fluvial experiment investigating the function of mussel posterior ‘ribbed’ sculpture. I measured water velocity magnitude, direction, and streambed erosion surrounding mussel models with sculpture and with their sculpture manually removed. In opposition to previous studies, I found more streambed erosion associated with sculptured models. However, mussel orientation to streamflow was the more significant driver to variations in water velocity magnitude, direction, and streambed erosion. This body of work illustrates the complementary nature of phylogenetic comparative methods and experiments to finding the evolutionary mechanisms of phenotypic variation. Lastly, the role of phenotypic plasticity in macroevolutionary outcomes has seldom been investigated but the widespread convergence of ecomorphological traits in chapter 1 and common garden experiment in chapter 2 suggest plasticity may be a key mechanism to macroevolutionary diversification.
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    Microglial morphology as a factor of sex and SNCA gene status
    (2022) Boes, Samuel A; Kim, Minwoo; Brown, Jennifer L; Lesné, Sylvain E
    Microglia comprise the immune system of the central nervous system. Microglia vary in morphology and in transcriptional and translational profiles. These factors are indicative of function and activation state. The role of the protein alpha-synuclein in neurons is established but remains unclear in microglia. Austin et al. (2006) found that cultured SNCA-knockout microglia display morphologically and translationally distinct profiles as compared to cultured wildtype neurons, but little work has been done to characterize microglial morphology in SNCA-knockout and wildtype mice in vivo. Because Brown et al. (unpublished) found changes in the expression of several genes associated with microglial activation in the hippocampi of SNCA-knockout mice compared to wildtype, the aim of this work was to determine the morphology of microglia in the CA1 of SNCA-knockout and wild-type mice. Confocal microscopy was used to capture high magnification and high resolution images of single microglia from SNCA-knockout and wildtype mice of both sexes (n = 40). Cell morphology was then characterized using Imaris Filament Tracer. SNCA-knockout exhibits a sex-dependent effect on microglial morphology. Microglia from SNCA-knockout female possess significantly more segments, branch points, and terminal points than do cells from wildtype females. These results are suggestive of a hypersurveillant microglial phenotype in SNCA-knockout females. More studies are warranted that compare the phagocytic activity and response to inflammation of microglia in SNCA-knockout and wildtype mice.
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    Morphology is a Link to the Past: examining formative and secular galactic evolution through morphology
    (2017-12) Galloway, Melanie
    Galaxy morphology is one of the primary keys to understanding a galaxy's evolutionary history. External mechanisms (environment/clustering, mergers) have a strong impact on the formative evolution of the major galactic components (disk, bulge, Hubble type), while internal instabilities created by bars, spiral arms, or other substructures drive secular evolution via the rearrangement of material within the disk. This thesis will explore several ways in which morphology impacts the dynamics and evolution of a galaxy using visual classifications from several Galaxy Zoo projects. The first half of this work will detail the motivations of using morphology to study galaxy evolution, and describe how morphology is measured, debiased, and interpreted using crowdsourced classification data via Galaxy Zoo. The second half will present scientific studies which make use of these classifications; first by focusing on the morphology of galaxies in the local Universe ($z<0.2$) using data from Galaxy Zoo 2 and Galaxy Zoo UKIDSS. Last, the high-redshift Universe will be explored by examining populations of morphologies at various lookback times, from $z=0$ out to $z=1$ using data from Galaxy Zoo Hubble. The investigation of the physical implications of morphology in the local Universe will first be presented in Chapter 4, in a study of the impact of bars on the fueling of an active galactic nucleus (AGN). Using a sample of 19,756 disk galaxies at $0.01 < z < 0.05$ imaged by the Sloan Digital Sky Survey and morphologically classified by Galaxy Zoo 2 (GZ2), the difference in AGN fraction in barred and unbarred disks was measured. A weak, but statistically significant, effect was found in that the population of AGN hosts exhibited a 16.0\% increase in bar fraction as compared to their unbarred counterparts at fixed mass and color. These results are consistent with a cosmological model in which bar-driven fueling contributes to the growth of black holes, but other dynamical mechanisms must also play a significant role. Next, the morphological dependence on wavelength is studied in Chapter 5 by comparing the optical morphological classifications from GZ2 to classifications done on infrared images in GZ:UKIDSS. Consistent morphologies were found in both sets and similar bar fractions, which confirms that for most galaxies, both old and young stellar populations follow similar spatial distributions. Last, the morphological changes in galaxy populations are computed as a function of their age using classifications from Galaxy Zoo: Hubble (Chapter 6). The evolution of the passive disc population from $z=1$ to $z=0.3$ was studied in a sample of 20,000 galaxies from the COSMOS field and morphologically classified by the Galaxy Zoo: Hubble project. It was found that the fraction of disc galaxies that are red, as well as the fraction of red sequence galaxies that are discs, decreases for the most massive galaxies ($\rm log(M/M_{\odot})>11$) but increases for lower masses. The observations are consistent with a physical scenario in which more massive galaxies are more likely to enter a red disc phase, and more massive red discs are more likely to morphologically transform into ellipticals than their less massive counterparts. Additionally, the challenges of visual classification that are particular to galaxies at high redshift were investigated. To address these biases, a new correction technique is presented using simulated images of nearby SDSS galaxies which were artificially redshifted using the FERENGI code and classified in GZH.
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    Order Trichoptera Kirby, 1813 (Insecta), Caddisflies
    (Magnolia Press, 2007) Holzenthal, Ralph W.; Blahnik, Roger J.; Prather, Aysha L.; Kjer, Karl M.
    The taxonomy, diversity, and distribution of the aquatic insect order Trichoptera, caddisflies, are reviewed. The order is among the most important and diverse of all aquatic taxa. Larvae are vital participants in aquatic food webs and their presence and relative abundance are used in the biological assessment and monitoring of water quality. The species described by Linnaeus are listed. The morphology of all life history stages (adults, larvae, and pupae) is diagnosed and major features of the anatomy are illustrated. Major components of life history and biology are summarized. A discussion of phylogenetic studies within the order is presented, including higher classification of the suborders and superfamilies, based on recent literature. Synopses of each of 45 families are presented, including the taxonomic history of the family, a list of all known genera in each family, their general distribution and relative species diversity, and a short overview of family-level biological features. The order contains 600 genera, and approximately 13,000 species.
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    Quantification of Intervertebral Disc Morphology: Alterations Associated with Age, Idiopathic Scoliosis, & Corrective Fusion Surgery
    (2022-08) Foltz, Mary
    Background: The intervertebral disc is altered naturally with aging, abnormally due to deformity, and mechanically due to surgery. Specifically, the structural integrity of the disc is altered, which may relate to the position of the nucleus pulposus (NP) with respect to the annulus fibrosus (AF). A typical, healthy disc has a centralized NP with a distinct transition to the AF (surrounds the NP). However, uncovering the altered morphology is not well understood. Objectives: The aims of this dissertation are: 1) characterize changes in disc morphology associated with age and degeneration in a back healthy cohort; 2) identify altered disc morphology and health in scoliotic discs compared to healthy controls; and 3) evaluate disc health and morphological alterations following corrective spinal fusion surgery. Methods: Following IRB approval, participants were enrolled (back healthy individuals and individuals diagnosed with adolescent idiopathic scoliosis). MRI (3T, Siemens, MAGNETOM) scans were then acquired. From sagittal images, qualitative degeneration of each disc was graded (based on the Pfirrmann scale). From axial images, quantitative degeneration of each disc was assessed via the NP signal intensity and signal volume. Additionally, the transition zone slopes (quantifying the distinction between the NP and AF) as well as the NP location were extracted from axial images, referred to as the disc morphology metrics. These disc health and morphology metrics were extracted from the MRIs to determine the change due to aging, scoliosis, and surgery. Results: Across the age spectrum, decreases in the transition zone slope magnitudes and anterior shift in the NP was observed with an increase in aging and disc degeneration. There was no change in the disc health metrics (NP signal intensity and signal volume) between control and scoliotic discs. In individuals diagnosed with scoliosis, the NP was located towards the convexity of the curvature and there was an increase in the convex transition zone slope compared to controls and the concave slopes. Following corrective spinal fusion surgery, there was no significant change in disc health or morphology metrics overtime (up to 2-years following surgery). However, there were significant differences between the adjacent and sub-adjacent disc levels for the disc health and morphology metrics (NP signal intensity, signal volume, transition zone slope, and NP location). Conclusions: Based on the MRI signal patterns, a shift in NP location along with altered transition zone slope magnitudes could be identified and provide information on underlying alterations to the structural integrity of the disc. Continued evaluation of the disc morphology through noninvasive MRI techniques may assist clinicians on patient specific treatment options.
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    Relativization in Ojibwe
    (2016-06) Sullivan, Michael
    In this dissertation, I compare varieties of Ojibwe and establish sub-dialect groupings for the larger grouping known as Southwestern Ojibwe, often referred to as Chippewa, an indigenous North American Indian language of the Algonquian family. Drawing from a vast corpus of both primary and archived sources, I present an overview of two strategies of relative clause formation and show that relativization appears to be an exemplary parameter in the grouping of Ojibwe dialect and sub-dialect relationships. Specifically, I target the morphological composition of participial verbs, known as participles in Algonquian parlance and show the variation of their form across a number of communities. In addition to the discussion of participles and their role in relative clauses, I present additional findings from my research, some of which seem to correlate with the geographical distribution of participles, most likely a result of historic movements of the Ojibwe people to their present location in the northern Midwestern region of North America. Following up on the previous dialect studies of Ojibwe primarily concerned with varieties of Ojibwe spoken in Canada (Nichols 1976; Rhodes and Todd 1981; Valentine 1994, to name a few), I present the first study of dialect variation for varieties spoken in the United States and along the border region of Ontario and Minnesota. By describing the data in a classic Algonquian linguistic tradition, I then recast the data in a modern theoretical framework, making use of previous theories for Algonquian languages (Bruening 2001; Brittain 2001) and familiar approaches such as feature checking (Chomsky 1993) and the Split CP Hypothesis (Rizzi 1997).
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    Revision and phylogeny of the caddisfly subfamily Protoptilinae (Trichoptera: Glossosomatidae) inferred from adult morphology and mitochondrial DNA
    (Magnolia Press, 2013) Robertson, Desiree R.; Holzenthal, Ralph W.
    Protoptilinae Ross, 1956, is the most diverse subfamily belonging to the saddle- or tortoise-case-making caddisfly family Glossosomatidae Wallengren, 1891. The subfamily has a disjunct distribution: 5 genera are known from the East Palaearctic and Oriental regions; the remaining 13 are restricted to the Nearctic and Neotropical regions. Monophyly of Protoptilinae and each of 17 genera was tested using 80 taxa, 99 morphological characters, and mitochondrial DNA (COI). Additionally, homologies of morphological characters were assessed across genera and a standardized terminology for those structures was established. Mitochondrial DNA data were unavailable for 55 of the 80 taxa included in this study. To test the effects of the missing molecular data, 5 different datasets were analyzed using both parsimony and Bayesian methods. There was incongruence between the COI and morphological data, but results suggest the inclusion of COI data in a combined analysis, although incomplete, improved the overall phylogenetic signal. Bayesian and parsimony analyses of all 5 datasets strongly supported the monophyly of Protoptilinae. Monophyly of the following genera was also supported: Canoptila Mosely, 1939; Culoptila Mosely, 1954; Itauara Müller, 1888; Mastigoptila Flint, 1967; Mortoniella Ulmer, 1906; Protoptila Banks, 1904; and Tolhuaca Schmid, 1964. Several taxonomic changes were necessary for classification to reflect phylogeny accurately. Accordingly, Matrioptila Ross, 1938; Poeciloptila Schmid, 1991; Temburongpsyche Malicky, 1992; and Nepaloptila Kimmins, 1964, are designated new junior synonyms of Padunia Martynov, 1910. Additionally, the endemic Caribbean genera Campsiophora Flint, 1964, and Cubanoptila Sykora, 1973, are designated new junior synonyms of Cariboptila Flint, 1964. Diagnoses and a key to the subfamilies of Glossosomatidae and world genera of Protoptilinae incorporating these taxonomic changes are provided.
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    Taxonomy and phylogeny of New World Polyplectropus Ulmer, 1905 (Trichoptera: Psychomyioidea: Polycentropodidae) with the description of 39 new species
    (Magnolia Press, 2010) Chamorro, Maria Lourdes; Holzenthal, Ralph W.
    The taxonomy of the New World species of Polyplectropus (Ulmer, 1905a) is revised to include detailed male and female diagnoses, descriptions, illustrations, distribution records, and keys to males of all species and species groups. A phylogenetic analysis based on 59 morphological characters, 89 of 92 (97%) New World Polyplectropus species, and 2 outgroup taxa was inferred using parsimony and Bayesian methods, which resulted in minor topological differences. Conflicting estimates of relationship among and within most species groups led to a less resolved Bayesian tree (vs. parsimony tree) due to high variation in rates of change among characters and an overall low number of characters. A new classification for New World Polyplectropus is proposed with revised characterization of 10 recognized species groups, 6 newly established. Four species remain unassigned to species group. A key to genera of New World Polycentropodidae, including a redescription of Polyplectropus is provided. The homology of the male genitalia of Polyplectropus is discussed. Ninety-two species are treated. The following 39 new species are described: Polyplectropus adamsae (Peru), P. alatespinus (Brazil), P. amazonicus (Brazil), P. andinensis (Argentina, Bolivia), P. blahniki (Venezuela), P. bolivianus (Bolivia), P. brasilensis (Brazil), P. brborichorum (Ecuador), P. cressae (Venezuela), P. colombianus (Colombia), P. corniculatus (Peru), P. cuzcoensis (Peru), P. ecuadoriensis (Ecuador), P. flintorum (Venezuela), P. gaesum (Brazil), P. guyanae (Guyana, Venezuela), P. hollyae (Brazil), P. hystricosus (Brazil), P. insularis (Panama), P. juliae (Brazil), P. kanukarum (Guyana), P. maculatus (Venezuela), P. manuensis (Peru), P. matatlanticus (Brazil), P. minensium (Brazil), P. novafriburgensis (Brazil), P. peruvianus (Peru), P. petrae (Brazil), P. pratherae (Brazil), P. puyoensis (Ecuador), P. robertsonae (Bolivia), P. rodmani (Brazil), P. rondoniensis (Brazil), P. tragularius (Brazil), P. tripunctatum (Peru), P. venezolanus (Venezuela), P. woldai (Panama), P. zamoranoensis (Honduras), and P. zuliae (Venezuela). Polyplectropus buchwaldi (Ulmer, 1911) is designated as a nomen dubium.
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    Understanding and Engineering Molecular Order in Organic Semiconductors
    (2017-08) Fielitz, Thomas
    Organic semiconductors often exist in disordered material phases which have sub-optimal optical and electrical properties. Bringing some degree of order to these materials with crystals and even oriented amorphous phases has been shown to be fruitful for many applications, but is challenging to achieve. This is largely because of the variability between different materials and poorly understood dynamics in device-relevant thin films. This thesis describes progress towards understanding and tuning crystallization and ordering in organic thin films to realize enhancement in parameters relevant to organic optoelectronic devices. In particular, this thesis demonstrates that in thin-film crystallization processes, the crystal structure, crystal shape, and growth type can be controlled most effectively with film thickness, temperature, and strategic incorporation of secondary additives within the film. These variables change the rate at which crystals grow as well as the crystal shape during growth by altering the ability of molecules to attach and conform to the growing crystal front. When films are heated to bring about these processes through increased molecular mobility, secondary processes may occur to transform the microscopic film morphology through the addition, subtraction, and long-range motion of material. This motion can be connected to substrate-film interactions and the material phase of the starting film. Material interactions within the film bulk can kinetically trap molecular conformations, with the extent of this trapping depending on interaction type and deposition conditions. These properties can be further exploited to produce useful and spontaneous structures within a thin film. Ultimately, the desired result of ordering an organic semiconductor is to produce more efficient and stable structures for devices. This is demonstrated here through engineering the motion of excited states with crystallization, then applying such techniques to different organic solar cell geometries to study how different crystallization methods affect device properties. First, the mobility of excited states in boron subphthalocyanine chloride (SubPc), an archetypal organic solar cell molecule, is shown to increase upon crystallization with rigorous calculations explaining the origin. Such an increase provides motivation to study the effects of induced crystallization via homoepitaxial growth using the well-studied transistor material rubrene in a solar cell geometry. This serves as a platform by which to generalize the study to mixed epitaxial growth in a material which is not intrinsically crystalline, showing marked morphological and electronic changes with changes in mixture composition. This is ultimately applied to heteroepitaxial growth of SubPc, which does not crystallize when deposited onto a template at ambient temperature. These projects explore crystallization techniques as a solution to improve the performance of organic solar cells, resulting in an improved fundamental understanding of such processes and avenues for future progress.