1,721,021 research outputs found
Seasonality of forest insects: why diapause matters
Full text linkInsects have major impacts on forest ecosystems, from herbivory and soil- nutrient cycling to killing trees at a large scale. Forest insects from temperate, tropical, and subtropical regions have evolved strategies to respond to seasonality; for example, by entering diapause, to mitigate adversity and to synchronize lifecycles with favorable periods. Here, we show that distinct functional groups of forest insects; that is, canopy dwellers, trunk-associated species, and soil/litterinhabiting insects, express a variety of diapause strategies, but do not show systematic differences in diapause strategy depending on functional group. Due to the overall similarities in diapause strategies, we can better estimate the impacts of anthropogenic change on forest insect populations and, consequently, on key ecosystems
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Succès invasif de deux insectes introduits aux Îles Kerguelen : le rôle des ajustements morphologiques et écophysiologiques aux nouvelles conditions environnementales
No full textThe success of invasive species depends on the adequacy between their life history traits and the environmental characteristics (biotic and abiotic) of their new habitats. The invasive success may then rely on pre-adaptation, be triggered by the release of some selection pressures, perturbations, or quick responses of the organism to the new selection pressures. Phenotypic plasticity and evolutionary processes are then prime components in biological invasions, so that invasive species can be considered as key models for monitoring ecological and evolutionary processes in real time. We thus investigated morphological and ecophysiological responses produced in time and space during the invasion of the sub-Antarctic Kerguelen Islands by the predatory ground beetle Merizodus soledadinus and the saprophagous blowfly Calliphora vicina, which possess contrasted life strategies. We show morphological differentiation among populations of M. soledadinus depending on their residence time, as well as rapid changes of the C. vicina's wing morphology in these islands where flightlessness is the rule. The invasion of M. soledadinus was studied with special emphasis on the role played by phenotypic plasticity in colonizing habitats that differ from native ones (physiological plasticity to salinity) and maintaining durable populations despite the negative feedback of this predator on the availability of its own prey (trophic plasticity). As they spread and encounter novel selection regimes, these adjustments at different timescales are of paramount importance in the invasive success of both these insect species.Le succès des espèces invasives dépend de l'adéquation entre leurs traits d'histoire de vie et les caractéristiques environnementales (biotiques et abiotiques) de leurs nouveaux habitats. Le succès invasif d'une espèce peut donc reposer sur sa pré-adaptation, être déclenché par la levée de certaines pressions sélectives, les perturbations, ou encore la réponse rapide de l'organisme aux nouvelles contraintes sélectives. La plasticité phénotypique et les processus évolutifs sont ainsi des paramètres essentiels dans les invasions biologiques, en faisant des situations privilégiées pour observer les processus écologiques et évolutifs en temps réel. Nous nous sommes intéressés aux réponses morphologiques et écophysiologiques exprimées dans le temps et l'espace au cours de l'invasion des Îles Kerguelen (archipel subantarctique) par le carabique prédateur Merizodus soledadinus et la mouche saprophage Calliphora vicina, dont les stratégies de vie sont contrastées. Nous montrons la différenciation morphométrique de populations de M. soledadinus en fonction de leur temps de résidence, ainsi que les changements rapides de la morphologie de l'aile de C. vicina dans ces îles où l'inaptitude au vol est la règle. Une attention particulière est accordée au rôle de la plasticité phénotypique de M. soledadinus dans la colonisation de nouveaux habitats (plasticité physiologique à la salinité) et dans son maintien durable malgré l'impact qu'il exerce sur la disponibilité des proies (plasticité trophique). Ces ajustements à plus ou moins long terme sont des éléments déterminants du succès invasif de ces deux insectes à mesure qu'ils progressent et rencontrent de nouveaux régimes de sélection
Variations on the Author
Full text link“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
Contrainte trophique et sénescence : Aspects écologiques et biochimiques de la résistance au jeûne en fonction de l'âge des adultes chez un diptère aptère, sacrophage et longévif.
No full textM2 Ecologie, Ethologie, Evolutio
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe 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
Does wing morphology of the active flyer Calliphora vicina change as it invades islands ruled by flightless insects?
No full textDispelling the Myths Behind First-author Citation Counts
Full text linkWe 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
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