1,720,981 research outputs found
Cymbulia parvidentata Pelseneer, 1888 (Mollusca, Cymbuliidae) in the Ligurian Sea: further evidence of Atlantic species incursions in the Mediterranean area
Full text linkWe report the first record of a stranded specimen of Cymbulia parvidentata, a pteropod species of Atlantic origin, in the Ligurian Sea. On 27 February 2022, six C. peronii and one C. parvidentata were collected on Borgio-Verezzi Beach (Savona, Italy - 44.16° N, 8.304633° W). Specimens were examined morphologically and biometrically. Measurements (length, width, height and wet weight) separated the two taxa, C. peronii being larger than C. parvidentata. The finding of C. parvidentata, which has only occasionally been reported in southern Italy, is remarkable and may be due to ascending Atlantic water (AW) pulses that reach the Ligurian Sea. This finding adds to the previous knowledge of other pelagic species of Atlantic origin that were found in the Ligurian Sea, suggesting the possibility of major on-going changes and a general "Atlantification". In order to determine the frequency of such events, it will be highly desirable to design specific citizen-science campaigns
Host-shift speciation in Antarctic symbiotic invertebrates: further evidence from the new amphipod species Lepidepecreella debroyeri from the Ross Sea?
No full textLepidepecreella debroyeri n. sp. (Amphipoda, Lysianassoidea) is described from specimens collected at Terra Nova Bay (Ross Sea, Antarctica) in the framework of several scientific expeditions of the Italian National Antarctic Research Program. This amphipod is an obligate parasite of the regular sea urchin Sterechinus neumayeri (Meissner, 1900) and
also occurs at diving depths. L. debroyeri n. sp. shares with Lepidepecreella andeep Berge, Vader & Lockhart, 2004, an abyssal species described for the Weddell Sea, an almost identical morphology and ecological traits, being both associated with sea urchins of two different families. This close relationship could be the result of a host-shift phenomenon that occurred during the high number of glacial cycles, possibly rendering the preferred host unavailable. L.
debroyeri n. sp. shows a high degree of variation in terms of sex ratio and population structure between
different host specimens, a fact that could be related to a great mobility of this small parasitic amphipod. The new amphipod species is itself the subject of a hyperparasitic interaction, carrying tantulocarid crustaceans on the pleopods. This represents the first record of a symbiotic interaction between a tantulocarid and an amphipod for the Southern Ocean
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
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
First record of living Acesta (Mollusca: Bivalvia) from an Antarctic seamount
No full textDuring a survey of Scott and Admiralty seamounts as part of the New Zealand IPY-CAML expedition in
2008, a number of new records and new species were documented (e.g., Bowden et al. 2011). Here we report on the finding of a single living specimen of Acesta sp. (station 207, Scott B seamount) and several loose valves, both recent and subfossil at seafloor photographic stations 198, 202, 207 (Scott B seamount), 219 (Scott A seamount) and of a single valve at epibenthic sled station 256 (Scott I seamount) (Fig. 1)
Developmental trade-offs in Southern Ocean mollusc kleptoparasitic species
No full textConnectivity is a key factor in determining the genetic structure of marine populations, and type and duration of the larval phase strongly affect dispersal abilities of species. In Antarctica, invertebrates show a higher proportion of species with limited pelagic dispersal, and any exception to this pattern is worthy of attention. Capulidae is a family of kleptoparasitic gastropods, with two larval strategies. Most species have a peculiar planktotrophic larva, the †̃echinospiraâ€TM, which enables a long pelagic dispersal; a minority of species undergo lecithotrophic development. We provide the first molecular phylogenetic framework for the family and define the Antarctic species based on molecular data. Based on this information, and on larval shell morphology, we tested the hypothesis that capulid species with high dispersal capacities via planktotrophic larvae display high genetic connectivity over long distances. Our data showed that whilst larval planktotrophy is the predominant larval strategy of the family worldwide, the vast majority of Antarctic species exhibit non-planktotrophic development. The unique exception, Capulus subcompressus, showed high genetic connectivity between the Ross Sea and Weddell Sea-Antarctic Peninsula. In all other Antarctic species, environmental constraints selected towards intracapsular metamorphosis, despite the associated limits of dispersal and finding a host. © 2015, Springer International Publishing Switzerland.}
Not All That Glitters Is Gold: Barcoding Effort Reveals Taxonomic Incongruences in Iconic Ross Sea Sea Stars
No full textinfo:eu-repo/semantics/publishe
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
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