1,720,956 research outputs found
Linking speciation and the niche: taxonomy, phylogeny and niche evolution in neotropical Begonia
No full textBegonia L. is one of the ten largest plant genera with >1,830 currently accepted species distributed throughout the tropical Americas, Africa and Asia. This exceptional diversity offers the opportunity to study the processes underlying recent and rapid radiations, including the theory of adaptive radiations, but also poses major challenges.
Methods to test adaptive radiation theory require sufficient occurrence data to produce species distribution models for the majority of species in a group. In many groups, including Andean, Central American and Mexican Begonia, this criterion is not met. The availability of specimen data on GBIF for species distribution modelling in vascular plants as a whole was assessed. The potential contribution of databased and freely available but indetermined or non-georeferenced specimens to the field of species distribution modelling was estimated. More than half of vascular plant species are currently unavailable for species distribution modelling. Our results indicate 22% of currently unavailable species could be modelled with already available herbarium data that is not yet georeferenced or determined to species. We argue that a greater focus on georeferencing and identification skills are vital if herbaria are to contribute fully to the growing field of species distribution modelling. We highlight those families and geographic regions that would most benefit from this approach and discuss the historical factors have influenced differences among regions.
Another prerequisite for species distribution modelling is a stable species level taxonomy. In preparation for investigation involving SDM’s in Begonia, five taxonomic papers are presented, including revised species concepts, distribution data suitable for use in species distribution models, seven new species and a new section of Begonia. Three plastid markers for 574 species and 809 accessions of Begonia were used to produce the largest, most representative phylogeny of Begonia published to date. An updated sectional classification of the genus is provided. The sections of Begonia are used frequently as analogues to genera in other families but, despite their taxonomic utility, few of the current sections have been examined in the light of molecular phylogenetic analyses. The relationships among some species and sections are poorly resolved, but many sections and deeper nodes receive strong support. We recognise 77 sections of Begonia including four new sections: Astrotricha, Jackia, Kollmannia, and Stellanthera; five sections are reinstated from synonymy: Australes, Exalabegonia, Latistigma, Pereira and Poecilia; and four sections are newly synonymised. The new sectional classification is discussed with reference to identifying characters and previous classifications.
Central to the theory of an adaptive radiation is that the majority of speciation events are adaptive, implying speciation driven by adaptation to different environments and resulting in niche shifts. Species in an adaptive radiation should display distinct ecological niches and environmental disparity across the group’s phylogeny should best fit a kappa ‘niche-shift’ or ‘speciational’ model of character evolution. These characteristics were tested in two clades of Neotropical Begonia. Species were compared through the comparison of their distributions in environmental space calculated from species distribution models. The fit of four models of environmental evolution (a kappa ‘niche-shift’ model, a Brownian motion model, an early-burst model, and a white noise model) to the observed niche disparity in the group were assessed using the Akaike Information Criterion
Patterns of ecological diversification in the two clades of Begonia examined strongly diverge from those predicted by an adaptive model, and we conclude Begonia is not an adaptive radiation with respects to climatic niche. Ecological disparity within Begonia clades best fits the predictions of a Brownian model of niche evolution. The characteristics of a Brownian model include constant niche evolution over the phylogeny, no increases in niche evolution during speciation, and independent niche evolution in sister lineages. This is incompatible with the predictions of an adaptive radiation. We suggest the remarkable diversity of the genus has developed through geographic speciation, and subsequent adaptation to local environments. This phenomenon may be widespread among plant radiations in topographically- and environmentally-heterogeneous areas, and a re-evaluation of putative adaptive radiations throughout the world’s montane regions may be necessary
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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