1,721,018 research outputs found
Estrutura populacional intraespecífica e diversidade genética de Osteocephalus taurinus (Anura: Hylidae) no interflúvio Purus-Madeira, Amazônia Central
Get PDFThe Amazon rainforest is the most biodiverse biome in the world, where amphibians are one of the biological groups with the highest levels of cryptic diversity reported across taxa. Despite noticeable efforts, processes driving differentiation among populations and speciation remains largely unknown in this biome, especially based on dense sampling over refined scales. We studied the population structure and genetic diversity of the Manaus slender ledged tree frog, Osteocephalus taurinus, along a geographic gradient of approximately 900 km. Using molecular markers including mitochondrial and nuclear genes, and microsatellites, we estimate the phylogenetic relationships, population structure, and patterns of intraspecific genetic variation and geographic differentiation through the study area. Our data recovered six genetic groups: two corresponding to O. taurinus and O. oophagus from its type locality, Reserva Ducke, at northern of Amazonas River. The third group corresponds to an O. taurinus population isolated at right bank of upper Madeira River. However, evidence for restricted gene flow was detected along the upper Madeira River. Within Purus-Madeira interfluve, the remaining three O. taurinus populations replace each other latitudinally along geographical and environmental gradients, with two contact zones identified. One contact zone is concordant between mitochondrial and nuclear DNA and corresponds to an ecotone region between closed- open rainforests. Following the riverine barrier hypothesis, natural selection by means of genetic drift is expected to cause differentiation among populations by large Amazonian rivers as vicariant barriers. Within continuous forested regions, abrupt transitions on gene frequencies are suggestive of narrow contact or tension zones. In those areas, selection is expected to be favored by local adaptation to different environmental conditions, given selection against dispersing migrants from immediate but environmentally distinct regions and against hybrids.A Amazônia é o bioma mais biodiverso da terra, e os anfíbios são um dos grupos com as maiores
taxas de diversidade críptica registradas nessa região. No entanto, os mecanismos causantes de
diferenciação entre populações e especiação mantem-se pouco conhecidos nesse bioma,
especialmente com base em amostragens densas em escalas refinadas. Estudei a estrutura
populacional e diversidade genética da rã hylídea Osteocephalus taurinus, ao longo de um
gradiente geográfico de aproximadamente 900 km na Amazônia central, Brasil. Usando
marcadores moleculares que incluíram DNA mitocondrial, nuclear e microssatélites, estudei as
relações filogenéticas, estrutura populacional, e padrões de variação genética intraespecífica e
diferenciação geográfica na área de estudo. Seis grupos genéticos foram recuperados pelas
análises: dois correspondem ao O. taurinus e O. oophagus de sua localidade tipo, Reserva
Ducke, ao norte do Rio Amazonas. O terceiro grupo corresponde a uma população de O.
taurinus isolada na margem direita do Rio Madeira superior. No entanto, evidência de fluxo
gênico restrito foi detectada no Rio Madeira superior. Dentro do interflúvio Purus-Madeira, as
três populações de O. taurinus substituíram-se ao longo de gradientes geográficos e ambientais,
com duas zonas de contato identificadas. Uma zona de contato é concordante entre o DNA
mitocondrial e nuclear, e corresponde a uma região no ecótono entre as florestas fechadas e
abertas. Segundo a hipótese de barreiras riverinas, espera-se que seleção natural causada por
deriva gênica cause diferenciação entre populações separadas por grandes rios Amazônicos
como barreiras vicariantes. Dentro de regiões contínuas de floresta, transições abruptas nas
frequências gênicas sugerem zonas estreitas de contato ou tensão ecológica. Nessas áreas,
espera-se que seleção seja favorecida por adaptação local às diferentes condições ambientais,
por meio de seleção contra migrantes de outras regiões imediatas, mas ambientalmente
distintas, e contra híbridos
FIGURE 1 in Phylogenetic relationships of the poorly known treefrog Boana hobbsi (Cochran & Goin, 1970) (Anura: Hylidae), systematic implications and remarks on morphological variations and geographic distribution
No full textFIGURE 1. Bayesian phylogenetic tree of the genus Boana, based on a fragment of the 16S mitochondrial rRNA, highlighting the position of Boana hobbsi (in yellow) in comparison to major clades representing known species groups, and indicating the phylogenetic position of remaining species included in the B. punctata group (in green). Support values are indicated close to the nodes. Branch scale is indicated as number of substitutions per site.Published as part of De Almeida, Alexandre P., Moraes, Leandro J.C.L., Rojas, Rommel R., Roberto, Igor J., Carvalho, Vinicius Tadeu De, Ávila, Robson W., Frazão, Luciana, Silva, Ariane A.A., Menin, Marcelo, Werneck, Fernanda P., Hrbek, Tomas, Farias, Izeni P. & Gordo, Marcelo, 2021, Phylogenetic relationships of the poorly known treefrog Boana hobbsi (Cochran & Goin, 1970) (Anura: Hylidae), systematic implications and remarks on morphological variations and geographic distribution, pp. 301-323 in Zootaxa 4933 (3) on page 305, DOI: 10.11646/zootaxa.4933.3.1, http://zenodo.org/record/455483
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
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