1,720,959 research outputs found
Dietary shifts in pollen-feeding lacewings (Nemopteridae) in relation to vegetation, biome and phylogeny
No full textIncludes bibliographical references.The spoon-winged and threadwinged lacewings are a diverse nemopterid family that have flourished in the winter rainfall region of South Africa. Their diversity is thought to be linked to the radiation of Aizoaceae, a member of the Ruchioideae subfamily that radiated at the same time as the recently diversified nemopterids in the Succulent Karoo. Phylogenetic data supported this assertion, and seperated the family into two distinct lineages, a recently diversified Aizoaceae-dependent Succulent Karoo lineage and a basal Aizoaceae-independent Fynbos lineage. This study aimed to determine if the nemopterid diet is phylogenetically contrained or if diet was mearely a reflection of plant availability. This was investigated by carrying out a dietary analysis of the gut contents of nemopterids from different biomes, vegetation and localities. It was hypothesised that diet would be phylogenetically constrained and dietary grouping would reflect phylogeny. In addition, the derived nemopterid lineage thought to have co-evolved with Aizoaceae, (Palmipenna, Nemopterella, Nemia, and Knersvlaktia) would reflect this in its diet. The older lineage (Nemeura, Sicyoptera, Semirhynchia, and Derhynchia) was hypothesised to have its phylogenetic grouping reflected in its diet by having very little to no Aizoaceae in its diet. The results showed that dietary groupings did not reflect phylogenetic groupings and dietary similarities were shared across most genera, including subfamilies, with Lauhervasia, a member of the Crocinae subfamily sharing 80% of its pollen sources with Semirhynchia, of the Nemopterinae subfamily. Aizoaceae reliance was only consistantly present in Nemia, which belonged to the phylogenetic lineage expected to rely on Aizoacea. All the members of the phylogenetic lineage not expected to rely on Aizoaceae, did not have any Aizoaceae in their diet. The diet of the nemopterids was very diverse across all vegetation types and biomes. The study suggests that spoon-winged and threadwinged lacewings are generalist pollinators and recent diversification was most likely linked to their ability to utilise the large range of available resources and not linked to a single plant family that radiated around the same time
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
The pollination and scent ecology of selected Cape milkweeds (Apocynaceae: Asclepiadoideae)
Get PDFMilkweeds (Asclepiadoideae, Apocynaceae) possess a complex floral morphology that has made them prime candidates for investigating the evolution of plant-pollinator relationships. In South Africa, the pollination ecology of this diverse group has largely been focused in the summer rainfall region. This study focused on Western Cape species in the winter and summer-winter rainfall transition zones. The aim was to determine the pollinators of the study species and assess, describe and quantify their floral attractants. Thus offering a basis of comparison with the previously studied summer rainfall species. The pollination systems of seven milkweed species occurring in the Western Cape were investigated by determining floral visitors and several floral traits that may act as attractants of these visitors. For each study species an attempt at pollinator observations was carried out in several sites across the Cape; floral scent samples were collected through headspace sampling and analysed using GC-MS (gas chromatography-mass spectrometry); floral colour was analysed using spectral reflectance measurements; and nectar was measured to quantify floral rewards. Some Cape milkweeds displayed a more generalized pollination system compared to their summer rainfall congeners. A diverse range of visitors were observed on two Gomphocarpus species, Gomphocarpus cancellatus and G. filiformis in the Fynbos and Succulent Karoo biomes respectively, in contrast to their summer rainfall congeners, which are exclusively wasp pollinated or much less generalized. These two Gomphocarpus species offered floral visitors nectar as a reward with a concentration of 53% in G. cancellatus and a lower 15% in G. filiformis. The species emitted very different scents, G. cancellatus produced a scent dominated by irregular terpenes while G. filiformis scent largely consisted of benzenoid compounds. Although visited by a variety of different insect families and lesser-double collared sunbirds, honeybees and Balbyter ants were found to be the most efficient at removing pollinaria from G. cancellatus and G. filiformis respectively. Eustegia minuta, a Cape endemic, is almost exclusively pollinated by bibionid flies. This is the first record of the pollinators for this monotypic genus, as well as the first for the tribe Eustegieae. Additionally, this study is the first record of a milkweed-bibionid pollination system. The flowers produced very low nectar volumes, displayed minimal visual cues but produced a strong pungent odour dominated by an unidentified compound. This strong scent is thought to play an important role in attracting bibionids while also deterring other potential visitors. The scent profiles of four other previously unstudied Cape milkweeds, namely Cynanchum obtusifolium, C. zeyheri, Fockea capensis and Secamone alpinii were also analysed and shown to be mainly dominated by monoterpenes and benzenoids. Their scent profiles differed markedly from each other as well as to their congeners. The presence of skatole in S. alpinii suggests that it may attract coprophagic flies, small Nematoceran flies were observed drinking nectar from its flowers. While F. capensis produced scent associated with moths. Further observations are needed to confirm true pollinators for both species. The two Cynanchum species produced scent that was very different to each other as well as their congeners. Cynanchum obtusifolium is known to be bee pollinated however its scent profile did not align with this. While C. zeyheri produced a benzenoid-dominated scent with compounds associated with moths. Scent appears to be the most prominent pollinator attractant in the study species compared to floral colour. The concentration and volume of nectar rewards may also be significant. The structural complexity of the flowers is suggestive of a strong floral filter in some species (e.g. Eustegia minuta). Morphologically similar species were found to employ vastly different floral chemical strategies to attract but possibly also deter and filter out floral visitors. The Cape milkweeds therefore offer many opportunities for further pollination studies
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
- …
