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The developmental basis of caste evolution in ants
No full textPhenotypic plasticity is the ability for a single genotype to give rise to alternative adaptive phenotypes in response to environmental conditions facilitating their survival. In some cases, environmental conditions can influence the course of development of an organism, leading to the induction of novel phenotypic variation, the raw materials for selection in evolution. Although this fact has the potential to unify the disparate fields of ecology, development and evolution, we have only begun to investigate the underlying molecular mechanisms that translate the environment into phenotypic diversity. Ants are highly plastic; during development a single genotype can give rise to an array of alternative phenotypes related to dramatic differences in morphology, longevity, reproduction and behavior. This environmental sensitivity is the basis for the diversity of complex ant caste systems. Here, I used ant development of the hyperdiverse genera Pheidole and Camponotus as models to investigate my major goal, which is to understand how ecology (environment) acts on development, generating morphological variation, which can then lead to morphological diversification and evolution. The first specific goal (Chapter 2) of my thesis is to investigate the hormonal and developmental genetic basis underlying the evolution of novel worker ant subcastes. Specifically, the genus Pheidole is composed of over 1000 species, all of which comprise a complex worker caste system of minor workers and soldiers. In a hand full of these species, there exists an additional novel worker subcaste, the supersoldier. Through phylogenetic and developmental genetic analysis, I determined that this subcaste has evolved in parallel in different species. I then discovered through field observations and hormonal manipulations that there exists an ancestral developmental potential in this group: all Pheidole species have the hidden capacity to produce supersoldiers through environmental induction, the recurrence of which can lead to their evolution. The second specific goal of my thesis (Chapter 4) is to investigate the epigenetic mechanisms that translate environmental conditions into morphological variation within castes. Specifically, I investigated the involvement of DNA methylation in generating continuous sizing in the worker caste of the genus Camponotus. I discovered that DNA methylation is responsible for generating a continuous distribution of worker size and that one of its primary targets is the gene Egfr. Furthermore, the methylation level of Egfr is associated with quantitative variation in worker size and pharmacological inhibition of EGFR signaling demonstrated that this pathway is capable of generating the continuous distribution of size found within this caste. DNA methylation is an epigenetic mechanism that is known to cause transgenerational inheritance and therefore it can facilitate the evolution of environmentally generated quantitative variation. Collectively, the results of my thesis show how the environment acts on development through the integration of hormones, genes and epigenetic mechanisms to generate phenotypic variation for selection to act on. Perhaps we are coming closer to a point in time in evolutionary theory when we can say that the environment is as important in generating phenotypic variation as it is in the process of selection.La plasticité phénotypique est l'habileté d'un génotype unique de produire des phénotypes adaptatifs alternes en réponse à des conditions environnementales facilitant leur survie. Dans certains cas, les conditions environnementales peuvent influencer le cours du développement d'un organisme, menant à l'induction d'une variation phénotypique nouvelle, qui est la matière brute pour la sélection en évolution. Bien que ce fait ait le potentiel d'unifier les champs distincts de l'écologie, du développement et de l'évolution, on commence seulement à étudier les mécanismes moléculaires fondamentaux qui traduisent l'environnement en diversité phénotypique. Les fourmis démontrent une grande plasticité phénotypique; durant le développement, un génotype unique peut produire une diversité de phénotypes adaptatifs qui démontrent des différences dramatiques de morphologie, de longévité, de reproduction et de comportement. Cette sensibilité environnementale est à la base de la diversité des systèmes complexes de castes chez les fourmis. Ici, j'ai utilisé le développement des genres hyperdiversifiés Pheidole et Camponotus comme modèles pour investiguer mon but principal, qui est de comprendre comment l'écologie (l'environnement) agit sur le développement, en générant de la variation morphologique qui peut par la suite mener à une évolution morphologique. Le premier objectif spécifique de ma thèse (Chapitre 2) est d'investiguer les bases hormonales et du développement des nouvelles sous-castes ouvrières chez les fourmis. Plus spécifiquement, le genre Pheidole est composé de plus de 1000 espèces, toutes démontrant un système de castes ouvrières complexe comprenant des ouvrières mineurs et des soldates. Chez un petit groupe de ces espèces, il existe une caste ouvrière additionnelle, la supersoldate. En utilisant des analyses phylogénétiques et de génétique du développement, j'ai déterminé que cette sous-caste a évolué en parallèle chez les différentes espèces. J'ai par la suite découvert, par des observations sur le terrain et des manipulations hormonales, qu'il existe un potentiel ancestral de développement dans ce groupe: toutes les espèces de Pheidole ont une capacité cachée de produire des supersoldates par induction environnementale, cette récurrence pouvant mener à leur évolution. Le second objectif spécifique de ma thèse (Chapitre 4) est d'investiguer les mécanismes épigénétiques qui traduisent les conditions environnementales en variation morphologique entre les castes. Plus spécifiquement, j'ai investigué le rôle de la méthylation de l'ADN dans l'élaboration d'une distribution de taille continue chez la caste ouvrière de Camponotus. J'ai découvert que la méthylation de l'ADN génère une distribution continue de taille chez la caste ouvrière et que l'une de ses cibles principales est le gène Egfr. D'ailleurs, le niveau de méthylation de Egfr est associé à une variation quantitative de la taille des ouvrières et une inhibition pharmacologique de la signalisation EGFR a démontré que cette voie de signalisation est capable de générer la distribution continue des tailles dans cette caste. La méthylation de l'ADN est un mécanisme épigénétique qui est connu pour causer une héritabilité transgénérationelle et donc, elle peut faciliter l'évolution d'une variation quantitative générée par l'environnement. Collectivement, les résultats de ma thèse montrent comment l'environnement agit sur le développement par l'intégration des hormones, des gènes et des mécanismes épigénétiques pour générer de la variation phénotypique sur laquelle la sélection naturelle peut agir par la suite. Peut-être que nous nous rapprochons d'un moment où la théorie de l'évolution peut proposer que l'environnement soit également important pour générer de la variation phénotypique qu'il peut l'être au cours du processus de sélection
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
Author Under Sail The Imagination of Jack London, 1893-1902
No full textIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Intro -- Title Page -- Copyright Page -- Dedication -- Contents -- Acknowledgments -- Introduction -- 1. Spirit Truth -- 2. From Absorption to Theatricality and Back Again -- 3. "I Will Build a New Present" -- 4. Sons as Authors -- 5. Fathers as Publishers -- 6. The Daughter as Author -- 7. Lovers as Authors -- 8. At Sea with the Family -- 9. Yellow News, Yellow Stories -- 10. The Return Home -- Notes -- Bibliography -- Index -- About Jay WilliamsIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
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