1,720,972 research outputs found
Taxonomic validity and phylogenetic relationships of a newly-described toothcarp, Aphanius mesopotamicus Coad, 2009 (Teleostei: Cyprinodontidae)
No full textAlavi-Yeganeh, Mohammad Sadegh, Keivany, Yazdan, Seyfabadi, Jafar, Kazemi, Bahram, Wallis, Graham P. (2014): Taxonomic validity and phylogenetic relationships of a newly-described toothcarp, Aphanius mesopotamicus Coad, 2009 (Teleostei: Cyprinodontidae). Zootaxa 3780 (3): 594-600, DOI: http://dx.doi.org/10.11646/zootaxa.3780.3.1
FIGURE 2 in Taxonomic validity and phylogenetic relationships of a newly-described toothcarp, Aphanius mesopotamicus Coad, 2009 (Teleostei: Cyprinodontidae)
No full textFIGURE 2. Maximum likelihood estimates of phylogenetic relationships of A. mesopotamicus with congeneric taxa using complete cytb sequences (1140 bp). Nodes are labeled with bootstrap support by ML (first value) and posterior probability of the Bayesian analysis (second value). Tree condensed to show only those nodes with values higher than 75%. Scale bar: nucleotide substitutions per sitePublished as part of Alavi-Yeganeh, Mohammad Sadegh, Keivany, Yazdan, Seyfabadi, Jafar, Kazemi, Bahram & Wallis, Graham P., 2014, Taxonomic validity and phylogenetic relationships of a newly-described toothcarp, Aphanius mesopotamicus Coad, 2009 (Teleostei: Cyprinodontidae), pp. 594-600 in Zootaxa 3780 (3) on page 596, DOI: 10.11646/zootaxa.3780.3.11, http://zenodo.org/record/506236
A Review of <i>Galaxias</i> (Galaxiidae) Fossils from the Southern Hemisphere
No full textThe Galaxiidae is a Southern Hemisphere family of freshwater fish, considered to be of Gondwanan origin based on the current distribution of species in New Zealand, Australia (including Tasmania), New Caledonia, Africa, South America, and on some associated and subantarctic islands. The fossil record of galaxiids is extremely sparse and geographically restricted. The only galaxiid fossils currently known come from several Miocene lakes in southern New Zealand. They include more than 100 articulated fishes, some remarkably preserving soft parts such as eyes and skin, skulls and jaw components, and more than 200 isolated otoliths. Common coprolites and in situ preserved gut content at one site (Foulden Maar) indicate the different diets of larvae and adult fish. These discoveries reveal a diverse Galaxias fauna, the presence of lake-locked populations, ontogenetic diet shifts, and representatives of several non-migratory Galaxias lineages associated with inland streams and lakes. There are at least six Galaxias species based on macrofossils and six separate otolith-based species from varied volcanic and regional lacustrine environments. This diversity points to southern New Zealand as a centre of biodiversity and speciation in Galaxiidae in the early to late Miocene.</p
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
The Rarotongan Lamprocystis: A new Pacific land snail radiation and a model for the study of sympatric speciation
No full textSympatric speciation, the idea that species can arise without a period of geographical isolation, is at the centre of one of the longest running and most contentious debates in evolutionary biology. In The Origin, Darwin presented a verbal model of speciation that did not require geographical isolation. Since that time, support for sympatric models of speciation has fluctuated markedly. Today, it is generally accepted that sympatric speciation is theoretically possible, but there are few empirical studies that show it has occurred in nature. Here, I present evidence that a morphologically diverse group of land snails from Rarotonga represent a previously unrecognised evolutionary radiation, and that this radiation very likely arose by sympatric speciation.
In particular, I use mitochondrial and nuclear DNA sequences and morphological characters to delimit seven species of Lamprocystis land snail, five of which were not previously recognised. A phylogenetic analysis incorporating these species and their relatives from across the Pacific establishes that this radiation arose within Rarotonga and a phylogeographic study of two of the Rarotongan species shows it is unlikely that geographic isolation within the island could explain their origin. Taken together, these studies make a strong, albeit circumstantial, case that the Rarotongan Lamprocystis radiation arose by sympatric speciation. However, the forces that drove the origin of these species remain unclear. Theoretical models that predict the possibility of sympatric speciation all include strong ecological competition between species as they begin to form. Ecological data collected for these species shows little evidence for such competition.
Several results produced here are of interest over and above their use in determining whether the Rarotongan Lamprocystis arose in sympatry. The delimitation of a new Pacific land-snail radiation is an important result in and of itself, as snails in the Pacific have contributed greatly to our understanding of evolution, but most previously studied radiations in this region are extinct or at risk of extinction. The particular approach I have taken to delimiting the species that make up this radiation should provide a model for the rapid and accurate species delimitation from molecular and morphological evidence. Finally, several results of taxonomic or conservation importance are discussed
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
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