Browsing by Author "Jamniczky, Heather A."

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    An Earliest Carboniferous Actinopterygian Fauna from the Horton Bluff Formation of Nova Scotia
    (2020-01) Wilson, Conrad Daniel Mackenzie; Anderson, Jason S.; Theodor, Jessica M.; Cote, Susanne; Jamniczky, Heather A.; Anderson, Jason S.
    This thesis examines four earliest Carboniferous (Tournaisian) actinopterygian specimens from the Horton Bluff Formation of Nova Scotia. I used traditional and μCT descriptive techniques in order to better understand actinopterygian evolution and the transition between Devonian and Carboniferous vertebrate faunas. NSM 017.GF.017.001 was investigated using microscopy and latex peel techniques and represents the oldest occurrence of a deep-bodied actinopterygian. NSM 017.GF.017.007 and NSM 017.GF.017.004 were investigated using microscopy and μCT. Neither specimen can be assigned to genus or species, however, each can be compared to a broader group. NSM 017.GF.017.007 is most similar to Devonian taxa, whereas NSM 017.GF.017.004 is most similar to actinopterygians deeply nested in a broad post-Devonian radiation. NSM 017.GF.017.005 was examined using μCT and was incorporated into a phylogenetic analysis. In this specimen, the plesiomorphic anatomy of the dermal shoulder girdle, pectoral fin, and opercular-gular series are contrasted with the derived anatomy of the hyoid arch. In the phylogenetic analysis, it is recovered as a late-diverging member of a grade of otherwise Devonian actinopterygians. The presence of NSM 017.GF.017.001 and NSM 017.GF.017.004 suggests that derived actinopterygians faunas were established by the Tournaisian; whereas the presence of NSM 017.GF.017.007 and NSM 017.GF.017.005 suggests that Hangenberg extinction survivorship was inclusive of early-diverging actinopterygians. NSM 017.GF.017.001 and NSM 017.GF.017.005 also evince actinopterygian body plan exploration, perhaps related to resource acquisition, in the Tournaisian and revise previous models of post-Hangenberg actinopterygian differentiation. More broadly, the disparity of this fauna weakens interpretations of a homogeneous earliest Tournaisian caused by mass extinction and suggest that faunal turnover was more gradual than expected, at least in Actinopterygii.
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    Ecology and Genetics of Phenotypic Integration and the Role for Adaptation in Threespine Stickleback
    (2019-07-09) Barry, Tegan Nicole; Rogers, Sean M.; Jamniczky, Heather A.; Theodor, Jessica M.; Vamosi, Steven M.
    Determining the underlying causes for the links between form, function, and the environment, and how these correlations relate to adaptation to novel environments represent integral problems in evolutionary biology. While investigations have been conducted on adaptive divergence involving single, isolated traits, adaptation is multifaceted, requiring the examination of complex, multidimensional phenotypes. In this thesis, I evaluated the hypothesis that phenotypic covariation and phenotypic integration are linked to genetic covariation and facilitate adaptation to novel environments. Phenotypic variation and covariation, along with genetic differentiation between multiple wild stickleback subpopulations and laboratory reared groups were described using three dimensional geometric morphometric data from stickleback skeletal structures as well as genomic information from high density Single Nucleotide Polymorphisms (SNPs; sensu Pool-Seq). I evaluated whether divergence in putatively adaptive traits was higher than expected under expectations for neutral evolution via PST-FST comparisons of phenotypic covariation and contrasted patterns of genetic and phenotypic variation. I determined the genetic basis of phenotypic integration using a controlled common garden experiment and investigated the genetic architecture of integrated skeletal structures through Quantitative Trait Locus (QTL) analysis carried out on linkage maps that I generated from SNPs characterized by double restriction digest reduced representation sequencing (ddRAD-Seq). Finally, I evaluated whether this genetic architecture was being maintained by selection in wild populations by testing the hypothesis that molecular divergence was higher than expected at genetic regions associated with phenotypic traits. I found the amount of phenotypic variation and strength of integration varies across the stickleback skeleton as well as among marine populations and that directional selection is acting on phenotypic integration in all observed populations. I determined that phenotypic integration across the skeleton is controlled by genetic factors, though there is a strong effect of environment on trophic traits. Finally, I characterized 33 significant QTL linked to integrated skeletal traits, finding 2702 SNP outliers within the identified QTL under selection between marine and freshwater environments. Collectively, my thesis highlights integration as an essential component of adaptive divergence and as one of the potential driving forces for the rapid adaptation of populations to novel environments.
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    Ecology of Adaptive Peak Shifts in Alaskan Threespine Stickleback (Gasterosteus aculeatus)
    (2015-12-04) Vanderzwan, Stevi Lee; Rogers, Sean M.; Vamosi, Steven M.; Jamniczky, Heather A.; Theodor, Jessica M.
    Divergent natural selection is a major cause of phenotypic differentiation among populations exploiting different environments, but information on the ecological factors contributing to peak shift is largely missing from natural populations. Threespine stickleback (Gasterosteus aculeatus) is an emerging vertebrate model for studying phenotype-environment associations, as ancestral marine populations have adapted independently to postglacial freshwater environments. I characterized antipredator, foraging, and body shape phenotypes of 800+ fish from 16 ecologically diverse sites on the Alaska Peninsula. Gill rakers, antipredator traits, and body shape significantly associated with lake ecology, whereas foraging traits and body shape were influenced by geography. Stickleback from lakes ecologically similar to the ancestral state were more phenotypically similar to marine-influenced populations than fish from ecologically divergent habitats (i.e., small lakes). My study elucidates mechanisms associated with adaptive evolution and is one of relatively few that links ecological features of the adaptive landscape with phenotypic evolution in multiple populations.
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    Estimating Cell Count and Distribution in Labeled Histological Samples Using Incremental Cell Search
    (2011-05-24) Meruvia-Pastor, Oscar E.; Soh, Jung; Schmidt, Eric J.; Boughner, Julia C.; Xiao, Mei; Jamniczky, Heather A.; Hallgrímsson, Benedikt; Sensen, Christoph W.
    Cell proliferation is critical to the outgrowth of biological structures including the face and limbs. This cellular process has traditionally been studied via sequential histological sampling of these tissues. The length and tedium of traditional sampling is a major impediment to analyzing the large datasets required to accurately model cellular processes. Computerized cell localization and quantification is critical for high-throughput morphometric analysis of developing embryonic tissues. We have developed the Incremental Cell Search (ICS), a novel software tool that expedites the analysis of relationships between morphological outgrowth and cell proliferation in embryonic tissues. Based on an estimated average cell size and stain color, ICS rapidly indicates the approximate location and amount of cells in histological images of labeled embryonic tissue and provides estimates of cell counts in regions with saturated fluorescence and blurred cell boundaries. This capacity opens the door to high-throughput 3D and 4D quantitative analyses of developmental patterns.
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    Impacts of non-native species on the morphology of threespine stickleback (Gasterosteus aculeatus)
    (2018-04-16) Kienzle, Hannah Marie; Vamosi, Steven M.; Jamniczky, Heather A.; Jackson, Leland J.
    Invasive species have demonstrated their capability to greatly modify ecosystems and communities. Introducing multiple species can potentially alter how a native population adapts relative to when species are introduced individually. I assessed whether native threespine stickleback (Gasterosteus aculeatus) exhibit distinct morphological characteristics corresponding to a varying combination of the presence of introduced smallmouth bass (Micropterus dolomieu) and signal crayfish (Pacifastacus leniusculus) on Vancouver Island. I also examined morphological changes over 18 - 43 years to determine whether contemporary characteristics become magnified in the presence of non-native species. There are clear distinctions in stickleback traits and body shape among non-native species combinations. Bass and crayfish lake stickleback are highly armoured, whereas bass-only lakes contain stickleback with reduced armour. Klein and Dougan Lake stickleback, which coexist with signal crayfish, showed significant increases in size over time. These patterns suggest that smallmouth bass and signal crayfish may have differential impacts on stickleback morphology.
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    Morphological integration and modularity of the mouse and hominoid skull: variation and epigenetic interactions during development
    (2011) Parsons, Trish Elizabeth; Hallgrimsson, Benedikt; Jamniczky, Heather A.
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    A multimethod analysis to assess locomotor capabilities in stem tetrapods from Blue Beach (Tournaisian; Early Carboniferous), Nova Scotia
    (2020-01) Lennie, Kendra Ilana; Anderson, Jason S.; Theodor, Jessica M.; Jamniczky, Heather A.; Manske, Sarah Lynn
    In vertebrate evolution the fin-to-limb transition was an important precursor to the diversification and radiation of terrestrial animals into novel environments. This transition began in the Devonian and continued through the Carboniferous and involved physiological and biomechanical changes. I used a multi-method approach to assess external and internal limb bone features to evaluate Early Carboniferous (Tournaisian) limb bones from Blue Beach and associated them with aquatic to terrestrial lifestyles. Tournaisian tetrapod material was collected at Blue Beach located near Hantsport, Nova Scotia, but much of it has not been formally described because the disarticulated and isolated tetrapod elements made identification to the species level difficult. In this thesis I described new morphotypes attributable to the family level which are used in the following chapters. Once the external morphology of the Blue Beach bones was described I compared them with the femora of extant aquatic, amphibious, and terrestrial tetrapods to evaluate which locomotor behaviour the fossil femora most resembled. I additionally examined cross-sectional bone profiles of Blue Beach tetrapod femora to infer lifestyle. Midshaft analyses relied on a single two-dimensional image to represent a dynamically structured bone so I also used a novel method for assessing three-dimensional trabecular data to qualitatively and quantitatively infer lifestyle from the Blue Beach femora. From the various analyses of internal and external bone morphology it was clear that external bone features of modern and early fossil tetrapod femora are dissimilar, which lead to difficulties in drawing conclusions based off external qualitative data. Internal data, from two-dimensional midshaft and three-dimensional trabecular structures, produced quantitative results that lead to the same conclusion, that the Blue Beach femora are consistent with those of aquatic animals. This implies that the initial diversification of the tetrapod body plans present in the Early Carboniferous was not the result of terrestrialization but appears to have preceded it.
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    Quantification of Learning in Anatomy Using Electroencephalography: A Neuroeducational Approach
    (2018-04-16) Anderson, Sarah Jayne; Hecker, Kent G.; Jamniczky, Heather A.; Coderre, Sylvain P.; Krigolson, Olav E.
    Technological advances enabling presentation of content stereoscopically provide a new forum for instructional design in anatomy education that instructors are keen to explore. Thus far, studies comparing the effectiveness of learning from two-dimensional (2D) versus three-dimensional (3D) visualizations demonstrate poor generalizability and are limited by reliance on behavioural evidence alone. Successful learning is, in essence, the result of changes in brain activity related to the proper storage and retrieval of information. Neuroeducational research offers the capacity to directly explore a learner’s cognitive processing without interfering with actual cognitive processing itself and can serve as an alternative measure for testing the efficacy of different teaching methods. The aim of this research was to quantify and explore behavioural and neural correlates measured by electroencephalography (EEG) as students recognize and learn from 2D and 3D representations in anatomy. To accomplish this aim, phases of this research entailed: designing and testing reinforcement-based learning activities specifically tailored for use in a neuroeducation research paradigm; demonstrating the utility of measuring amplitude changes of event-related potential components (ERPs) measured by EEG as quantitative dependent variables of learning, retention, and transfer of knowledge; and finally, comparing neural activity of subjects learning from anatomical representations with and without stereopsis. Specifically, this work examined changes in amplitude of the N250 (a measure of visual perceptual expertise) and reward positivity (sensitive to externally provided positive feedback) ERPs. This research shows that (1) changes in neural signals indicate progression in stages of learning, (2) learning with stereoscopic models is advantageous, and (3) that a reinforcement-learning paradigm is a successful approach to teach foundational knowledge in anatomy. This research provides a foundation upon which to build a program of neuroeducational research targeted specifically at health professionals in a real-world teaching and learning environment. Importantly, this work is some of the first to provide evidence that explicitly links behavioural and neuroscientific theories of learning in an applied educational context. Further, this work demonstrates where there are synergies across these theories but also highlight the potential pitfalls of sole reliance on behavioural data alone to inform our understanding of learning.