1,721,003 research outputs found
An evaluation of the taxonomic status of Musa viridis and Musa splendida using high-throughput sequencing data
No full textThe delimitation of species based on morphological traits can be challenging due to overlapping trait variation. The taxonomic identity of closely related sympatric species with individuals displaying intermediate phenotypes is particularly questionable. However, thorough morphological assessments or traditional molecular analyses often lack resolution to clarify if two species are truly separate taxonomic entities or should be merged. Interestingly, advances in high-throughput sequencing methods and data processing during the last decades enable the use of high-resolution data to tackle taxonomic problems. Several species with an unclear taxonomic status are found in the banana family (Musaceae). In Vietnam, the Musa species M. viridis and M. splendida have very similar morphological trait characteristics. The main difference between the two species is the colour of the male flower bud: M. splendida has red flower buds, whereas M. viridis has pink flower buds. Both species occur sympatrically, and individuals with red and pink male flower buds are found together in some populations. In this study, we used high-throughput (DArT) sequencing data from plants of nine populations to investigate the taxonomic status of these Musa species. Maximum likelihood phylogenetic trees were reconstructed for over 12,000 loci (< 120 base pairs) and one ASTRAL consensus tree was created from all locus trees. The individuals in the ASTRAL phylogenetic tree did not cluster by species identity, but by population, having individuals from different species in the same cluster. Consequently, we propose to merge the species M. viridis and M. splendida into one species named M. splendida according to nomenclatural conventions
An evaluation of the taxonomic status of Musa viridis and Musa splendida using high-throughput sequencing data
No full textThe delimitation of species based on morphological traits can be challenging due to overlapping trait variation. The taxonomic identity of closely related sympatric species with individuals displaying intermediate phenotypes is particularly questionable. However, thorough morphological assessments or traditional molecular analyses often lack resolution to clarify if two species are truly separate taxonomic entities or should be merged. Interestingly, advances in high-throughput sequencing methods and data processing during the last decades enable the use of high-resolution data to tackle taxonomic problems. Several species with an unclear taxonomic status are found in the banana family (Musaceae). In Vietnam, the Musa species M. viridis and M. splendida have very similar morphological trait characteristics. The main difference between the two species is the colour of the male flower bud: M. splendida has red flower buds, whereas M. viridis has pink flower buds. Both species occur sympatrically, and individuals with red and pink male flower buds are found together in some populations. In this study, we used high-throughput (DArT) sequencing data from plants of nine populations to investigate the taxonomic status of these Musa species. Maximum likelihood phylogenetic trees were reconstructed for over 12,000 loci (< 120 base pairs) and one ASTRAL consensus tree was created from all locus trees. The individuals in the ASTRAL phylogenetic tree did not cluster by species identity, but by population, having individuals from different species in the same cluster. Consequently, we propose to merge the species M. viridis and M. splendida into one species named M. splendida according to nomenclatural conventions
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
Herbaria as Functional Trait Databases
No full textAlthough tropical rainforests play an important role in regulating the world's climate, they are at the same time particularly vulnerable to changes in the climate. Intense and prolonged droughts, for instance, can lead to biomass loss which will further accelerate these changes. Especially for tree species it becomes problematic, due to their long lifespan, to quickly adapt to or evade unfavorable climatic conditions affecting the composition of the forest community as a whole and consequently the ecosystem services that the rainforests provide.
A long-term drying trend currently threatens tropical regions worldwide but is especially strong in the central African rainforest, the second-largest rainforest on Earth. The impact of this decrease in precipitation on the vegetation is, however, still largely unknown due to the limited amount of historical eco-climatological data. Fortunately, these kind of data do exist albeit in a poorly accessible (analog) format in herbarium collections.
To investigate if trees show changes in morphology and/or physiology invoked by climatic changes in the last century, the COBECORE team (Congo Basin Eco-Climatological Data Recovery and Valorization") is exploring the usability of herbaria as potential sources of plant leaf functional trait data using established protocols adjusted to dried leaf material. Photosynthesis as well as gas exchange and transpiration are processes regulated by a plant's leaves, and depend on the specific leaf area (SLA) and the number and size of the stomata. The less area the latter structures occupy on the leaf the less the plant will suffer from water losses which increases the resistance to drought of plants.
We explored the recently digitized African Herbarium of the Botanic Garden Meise which contains over 1.2 million African specimens with a very good coverage of the Congo Basin, dating back to 1880. Currently, we obtained average SLA measurements for 833 herbarium specimens from 59 of the most common tree species of central African rainforests. Pictures for stomata counts and size measurements were taken from over one hundred specimens mainly focused on three Prioria species, giant tree species (up to 60 metres) currently suffering from overexploitation. The data generated in this project will be valuable to understand some lower-level vegetation responses such as plant water use needed to model and predict long-term climate change impacts on vegetation
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
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