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Phylogenetics, systematics and biogeography of deep-sea Pennatulacea (Anthozoa: Octocorallia): evidence from molecules and morphology
No full textDespite its extreme environmental conditions, the deep sea harbours a unique andspecies-rich fauna of mostly unknown age and phylogeny. Pennatulids (Anthozoa:Octocorallia) are a group whose taxonomy and phylogenetic relationships remain poorlyknown and little studied, in spite of their abundance and ecological importance in softbottomcommunities. Phylogenetic analysis of a combination of partial ND2 and msh1sequences produced well-supported phylogenetic relationships for representative deepsea(and shallow-water) pennatulids at familial, generic and specific taxonomic levels.Generally, molecular data were congruent with current classification and previousphylogenetic reconstructions of the O. Pennatulacea based on morphology.Discrepancies were evident concerning the finer details for some families and genera: thiscan be attributable to the high frequency of homoplasy in pennatulids where reversals inevolution have led to taxa that possess apomorphic character states that are analogouswith plesiomorphic traits. Genetic analysis gave strong support that highly-derived taxaoccur in both shallow and deep water and that many may have differentiated anddispersed from the deep sea to the shallows. The Renillidae, which is considered one ofthe most primitive shallow-water families, evolved recently from deep-water ancestors.Conversely, the bathyal Anthoptilidae was the most primitive of families, and althoughmore evidence is required, pennatulids as a group may have originated in deep water.The systematics of the exclusively deep-sea genus Umbellula, which contains fortytwospecies, remains unclear despite the repeated attempts of revision. Incorporatingnew morphological and distributional data from the examination of recently collectedmaterial, together with type specimens, genetic analysis, and a critical study of theliterature, fifteen Umbellula species are here considered valid, including three new toscience. Eight species lack sclerites in the autozooids, U. magniflora, U. encrinus, U.antarctica, U. carpenteri and Umbellula sp.1 n. sp. (quadrangular axes), and U. huxleyi andU. pellucida (round axes); and seven possess autozooid sclerites, U. thomsoni and U.hemigymna (quadrangular axes), and U. monocephalus, U. aciculifera, U. durissima,Umbellula sp.2 n. sp. and Umbellula sp.3 n. sp. (round axes).Biogeographic data and genetic evidence supported the hypothesis that species ofUmbellula differentiated in the Indo-Pacific. Many radiated southwards to the Antarcticand later north into the Atlantic, E Pacific, Indian and Arctic oceans, occupying bathyaland abyssal depths. Other, older species that evolved via a separate evolutionarypathway, may have originated in the Indo-Pacific, and dispersed to the Subantarctic (U.sp.2 n. sp.) or Indian and Atlantic oceans (U. monocephalus). Further, morphologicalexamination of Umbellula showed it adapted to the oligotrophic conditions of the deepsea by reducing the number but increasing the size of the autozooids, and in doing so,enlarged the food-catchment area; abyssal species have done so even more extremely
Gametogenic periodicity in the chemosynthetic cold mussel 'Bathymodiolus' childressi
No full textThe gametogenic periodicity of the cold seep mussel “Bathymodiolus” childressi was analysed from a time series of samples from depths of ~650m surrounding the Brine Pool cold seep on the continental slope of the northern Gulf of Mexico. Occasional samples were retrieved from Bush Hill and GC 234 for comparison. At the Brine Pool, both females and males showed strong reproductive periodicity with the initiation of gametogenesis from December to March, followed by a period of gamete growth or proliferation and spawning from October through February. Gametogenesis was synchonized at all three sites. Gametogenic periodicity appears to be correlated with surface production that peaks during the winter months. Downward flux of detritus during this period may provide food for the planktotrophic larvae and also supplementary nutrition for the adult, which has chemosynthetic bacterial symbionts but is also capable of filter feeding. Individuals in all three populations carried parasites and these were especially common at Bush Hill and GC234, where it is suggested they have a major impact on reproductive output
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
Pitch vs. timbre
Full text linkEarly comparative musicology habitually ignored, even extinguished, timbre in its single-minded focus on pitch. This chapter traces the broader social, cultural, and political consequences of this framework. It surveys how, at the turn of the twentieth century, John Comfort Fillmore and Benjamin Ives Gilman followed the lead of Alice Fletcher and Alexander Ellis in deploying a broad range of technologies—phonograph, Helmholtz resonator, keyboard, and musical notation—to develop frameworks for analyzing essential similarities and differences between Native American and Western musics. It argues that such scholarship, while ostensibly aimed at salvaging Native American music, also served American efforts to reform and silence indigenous voices. The postscript examines the resonances between their theories and modern frameworks of parametric analysis that construe pitch and timbre as autonomous, and proposes that there may be unrecognized perils in overly articulating the boundaries between pitch and timbre to focus analytical attention exclusively on the measurable quantities of musical sound
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
Phylogeny and systematics of deep-sea sea pens (Anthozoa: Octocorallia: Pennatulacea)
No full textMolecular methods have been used for the first time to determine the phylogeny of families, genera and species within the Pennatulacea (sea pens). Variation in ND2 and mtMutS mitochondrial protein-coding genes proved adequate to resolve phylogenetic relationships among pennatulacean families. The gene mtMutS is more variable than ND2 and differentiates all genera, and many pennatulacean species. A molecular phylogeny based on a Bayesian analysis reveals that suborder Sessiliflorae is paraphyletic and Subselliflorae is polyphyletic. Many families of pennatulaceans do not represent monophyletic groups including Umbellulidae, Pteroeididae, and Kophobelemnidae. The high frequency of morphological homoplasy in pennatulaceans has led to many misinterpretations in the systematics of the group. The traditional classification scheme for pennatulaceans requires revision
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