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Echiniscus Virginicus Complex: The First Case of Pseudocryptic Allopatry and Pantropical Distribution in TardigradesGąsiorek, Piotr, Jackson, Kathy J., Meyer, Harry A., Zając, Krzysztof, Nelson, Diane R., Kristensen, Reinhardt M., Michalczyk, Łukasz 01 January 2019 (has links)
Mainly because of the problems with species delineation, the biogeography of microscopic organisms is notoriously difficult to elucidate. In this contribution, variable nuclear and mitochondrial DNA markers were sequenced from individual specimens representing the Echiniscus virginicus complex that are morphologically indistinguishable under light microscopy (five populations from the temperate Eastern Nearctic and 13 populations from the subtropical and tropical zone). A range of methods was used to dissect components of variability within the complex (Bayesian inference, haplotype networks, Poisson tree processes, automatic barcode gap discovery delineations, principal components analysis and ANOVA). We found deep divergence between the temperate Eastern Nearctic E. virginicus and pantropical Echiniscus lineatus in all three genetic markers. In contrast, intraspecific genetic variation was very low, regardless of the geographical distance between the populations. Moreover, for the first time, statistical predictions of tardigrade geographical distributions were modelled. The factor determining the allopatric geographical ranges of deceptively similar species analysed in this study is most likely to be the type of climate. Our study shows that widespread tardigrade species exist, and both geographical distribution modelling and the genetic structure of populations of the pantropical E. lineatus suggest wind-mediated (aeolian) passive long-distance dispersal.
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Latitudinal Gradients in Body Size in Marine TardigradesBartels, Paul J., Fontaneto, Diego, Roszkowska, Milena, Nelson, Diane R., Kaczmarek, Łukasz 16 March 2020 (has links)
Homeotherms and many poikilotherms display a positive relationship between body size and latitude, but this has rarely been investigated in microscopic animals. We analysed all published records of marine Tardigrada to address whether microscopic marine invertebrates have similar ecogeographical patterns to macroscopic animals. The data were analysed using spatially explicit generalized least squares models and linear models. We looked for latitudinal patterns in body size and species richness, testing for sampling bias and phylogenetic constraints. No latitudinal pattern was detected for species richness, and sampling bias was the strongest correlate of species richness. A hump-shaped increase in median body size with latitude was found, and the effect remained significant for the Northern Hemisphere but not for the Southern. The most significant effect supporting the latitudinal gradient was on minimum body size, with smaller species disappearing at higher latitudes. Our results suggest that biogeographical signals were observed for body size, albeit difficult to detect in poorly studied groups because of swamping from biased sampling effort and from low sample size. We did not find a significant correlation with the latitudinal pattern of body size and ecologically relevant net primary productivity.
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Race, Space, and Narrative: Spatial Reading and Racial Literacy in Contemporary Multifocal American NovelsErika Gotfredson (16558647) 18 July 2023 (has links)
<p>This dissertation identifies four American novels published between 2016 and 2018—Colson Whitehead’s <em>The Underground Railroad</em> (2016), Jesmyn Ward’s <em>Sing, Unburied, Sing</em> (2017), Celeste Ng’s <em>Little Fires Everywhere</em> (2017), and Tommy Orange’s <em>There There</em> (2018)—that deploy a multifocal narrative structure to facilitate readers’ ethical engagement with their content. Specifically, these novels’ narrative structures guide readers through spatial reading, or reading across numerous characters’ perspectives of a shared space instead of with the grain of chronological time. Contextualizing these novels within the nation’s shifting racial beliefs initiated by the election of Barack Obama in 2008 and the election of Donald Trump in 2016, I argue that, in these novels, multifocalization and the spatial reading it activates dismantle the cognitive schemas and cultural discourses that sustain unjust racial ideologies. Spatial reading engages readers in acts of rereading and contextualization that diverge from the practices of generalization and erasure affiliated with myths of racial progress and the rhetoric of colorblindness, and it accordingly builds readers’ capacity to acknowledge racism as systemic, structural, and multifaceted. By emphasizing how each novel facilitates readers’ racial literacy, this project diverges from and complicates the widespread belief that the humanities contribute to antiracism by building readerly empathy, instead championing how the humanities impart upon readers the tools to analyze and critique systemic racism. </p>
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A promise kept: the mystical reach through lossCollins, Jody 04 October 2019 (has links)
The meaning of loss is love. I know this through attention to experience. Whether loss or love is experienced in abundance or in absence, the meaning is mystical with an opening of body, mind, heart and soul to spirit. And so, in the style of a memoir, in the way of contemplative prayer, I contemplate and share my soul as a promise kept in the mystical reach through loss. With the first, initiating loss, the loss of my nine-year-old nephew, Caleb, I experience an epiphany that gives me spiritual instructions that will not be ignored. I experience loss as an abundance of meaning that comes to me as gnosis, as “knowledge of the heart” according to Elaine Pagels or divine revelation in what Evelyn Underhill calls mystical illumination in the experience of “losing-to-find” in union with the divine. Then, with gnostic import, in leaving the ordinary for the extraordinary, I enter the empty room in the painful yet liberating experience of the loss of my self. In the embrace of emptiness, I proceed to the first wall, the second wall, the third wall, the dark corner of denial, the return to centre, and, finally, to breaking the fourth wall in the empty room so as to keep my promise to you. Who are “you”? You are God. You are Caleb. You are spirit. You are my higher soul or self. And, you are the reader. You are my dear companion in silence. And then, through a series of broken promises and more loss, within what John of the Cross calls, “the dark night of the soul,” I am stopped by the ineffability of the dark corner of denial, the horror of separation and the absence of meaning, which is depicted as the grueling gap between the spiritual abyss and the breakthrough. What does it mean to keep going through a solemn succession of losses? I don’t know. In going into the empty room, I simply put pain to work in order to reach you. Through loss, though there are infinite manifestations, there is only one way: keep going. And so, in a triumph of the spirit, I keep going so as to be: a promise kept in the mystical reach through loss. As for you, through my illumined and dark experiences of loss, what is my promise to you? I keep going to reach the unreachable you. In the loss of self, with embodied emptiness, in going into the dark corner of denial, with a return to the divine centre of my emptied self, in an invitation to you, I give my soul to you in union with you. / Graduate / 2020-06-25
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