1,720,959 research outputs found
Relationships between morphological characters and fitness components in three close populations of Lestes barbarus (Odonata: Lestidae).
No full textSurvival and mating success are two components of fitness that have often been often thought to be related with several individual characteristics. Among these SIZE and Fluctuating Asymmetry are the most frequently investigated, and many studies have been done on adult Odonata, because of their well known behaviour and the facility with which they can be observed, caught and measured.
We investigated these relationships in three close populations of another odonate species, Lestes barbarus, whose longer pre-reproductive period allows the time for the selection to act, and whose philopatry allows us to measure the effect. Furthermore, we also investigated relationships between male mating success and SIZE, FA, thorax and total weights and their ratio.
Our results have shown that there were no uniform effects of the selection on the three populations, but there were different effects on some of these: stabilizing, disruptive and directional selection.
These results show that the morphological characteristics can affect natural selection in different ways even in populations very close to each other and in apparently similar environmental conditions.
This might explain why a lot of studies on relationships between SIZE, FA and fitness performances, usually done on a single population, have so often given contrasting results
Mountain biogeography: does the temporal evolution in “sky island” area matter?
Full text linkThe idea of considering higher elevation areas as islands with own, unique biological communities and surrounded by an “ocean” of unsuitable lands is not new in biogeography. However, a quantitative assessment of the effects of past climate fluctuations on islands’ dimension is crucial in view of climate warming. During the Holocene, islands’ boundaries experienced repeated altitudinal fluctuations due to changes in climate conditions. As a consequence islands’ areas were subject to variations of different intensity and alterations in inter-island connectivity. During the warmer phases some islands reduced strongly or disappeared, provoking the partial or complete extinction of the local biota. The subsequent cooling allowed a new rise and expansion of these islands, but, depending on the distance from a stable source and on the dispersal abilities of the species, the failure in the recolonization process could have provoked strong immigration credits. Aim of the present contribution is to discuss the combined effects of landscape and historical factors in shaping the current communities of mountain islands. Specifically, we modelled past island dynamics at a millennial scale in the last 11,000 years in Italy and analysed the effects of mountain islands fluctuations, by using montane butterflies, ground beetles, grasshoppers and crickets as biological models
Deciphering range dynamics: effects of niche stability areas and post-glacial colonization on alpine species distribution
No full textAim: Niche stability areas (NSAs) are portions of the species range where climate conditions remain suitable through time. They represent the core of species ranges. Their distribution and extent, coupled with dispersal and colonization, shape the realized range of species. In this study, we quantified the roles of survival within NSAs and post-glacial dispersal in determining the current distribution of two groups of alpine butterflies (two taxa in the Erebia tyndarus species complex; three taxa in the Parnassius apollo–P. phoebus species complex).
Location: Holarctic.
Methods: NSAs were identified for each taxon by combining current and past potential distributions models, estimated using different modelling techniques and general circulation models. We then (1) assessed the distributional bias towards NSAs by comparing actual occurrence records with randomized occupancies of the current potential range and (2) quantified post-glacial dispersal by examining the distribution of distances from each occurrence record to the nearest NSA.
Results: In almost all taxa, realized distributions are biased towards NSAs. However, while Erebia's present range is strongly dominated by NSAs, some populations of Parnassius are found very far from NSAs, suggesting more effective colonization of the available geographical space.
Main conclusions: Our study highlights the relative roles of survival within NSAs and post-glacial dispersal in shaping the ranges of different alpine butterflies during the Holocene. Results suggest that Erebia was unable to disperse far from NSAs, thus experiencing increasing range fragmentation. Parnassius populations, on the other hand, coupled local survival with northward dispersal. As NSAs allowed the long-term survival of the species, acting as sources for recolonization, and tend to preserve most of each species’ genetic diversity, identifying NSAs and understanding their importance in determining the current distribution of species represents a pivotal task for the conservation of biological diversity
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
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
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
Dispelling 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
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
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