1,720,968 research outputs found
Brachypterinae Erichson, 1845 (Insecta, Coleoptera) and Brachypterinae Zwick, 1973 (Insecta, Plecoptera): proposed removal of homonymy.
No full textA multimethod approach to the zoogeography of the Italian river basins, based upon distributional data of freshwater invertebrates I. The genus Hydraena Kugelann s.l. (Coleoptera, Hydraenidae).
No full textPatterns of genetic differentiation and gene flow in Central Italian populations of Dinocras cephalotes (Curtis, 1827) (Insecta, Plecoptera).
No full textDispersal is a crucial phenomenon which has a strong influence on the ecology and evolution of species, determining the extent of gene flow among conspecific populations. In this paper, we present data on the degree of genetic structuring in 11 populations of the stonefly Dinocras cephalotes, focusing our attention on three Central Italian rivers: Aniene, Nera and Velino. We studied the genetic variation at 28 enzymatic loci by means of starch gel electrophoresis: 19 loci were polymorphic in one population at least. The degree of genetic structuring and levels of gene flow were estimated by F-statistics using WEIR & COCKERHAM'S estimators. Relatively high levels of genetic differentiation were revealed, considerably higher than those obtained in other studies of stonefly species. Neighbour-joining analysis provided a geographic scheme of relationships of the study populations, grouping them according to the river of origin. This analysis was supported by bootstrap values. We were not able to detect an unequivocal relationship between gene flow and geographic distances between sites within each river; this led us to hypothesise that equilibrium has not been reached between genetic drift and gene flow
Un approccio multimetodo alla biogeografia dei sistemi reici italiani (Coleoptera, Hydraenidae; Plecoptera; Ephemeroptera).
No full text
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
Molecular systematics and biogeography of the western Mediterranean stonefly genus Tyrrhenoleuctra (Insecta, Plecoptera)
No full textThe stonefly genus Tyrrhenoleuctra includes species living in western Mediterranean temporary freshwater streams, sometimes also at sea level, a very unusual habitat for most Plecoptera. Traditional morphological approaches proved unsuccessful in drawing both taxonomic and phylogenetic patterns, thus hampering discussion of biogeographical patterns for this interesting group. We aimed at: (a) assessing the taxonomic status of populations of Tyrrhenoleuctra covering the geographic range of the genus; (b) studying the phylogenetic relationships among the recognized species; and (c) describing biogeographic patterns. We used phylogenetic analyses to infer the phylogenetic history of this group of stoneflies based on a combined data set of 1666 bp including fragments of the 12S ribosomal (12S) and cytochrome oxidase I (CO-I) mtDNA genes, with maximum likelihood and Bayesian methods. Two main clades have been identified: a Sardo-Corsican one, including Tyrrhenoleuctra zavattarii, and an Ibero-Maghrebian one including four lineages of unkown taxonomic rank from the Balearic Islands (Maiorca), from northern Africa (Ceuta) and southernmost Spain (Algeciras), and a complex preliminarily referred herein to T. minuta (Klapálek, 1901), which includes two lineages, one from Cordoba, and one from Sierra de Grazalema (El Cerro) and Portugal (Tellhares) respectively. Dating the nodes by fixing the split of the Ibero-Maghrebian clade from the Sardo-Corsican one at 29 million years ago (Mya), yielded dates referring to the major geological events in the Mediterranean basin. Estimated molecular evolutionary rates ranged from 0.02-0.09% per million years (my) in the T. zavattarii lineages, to 0.2-0.7% per MY in the Ibero-Maghrebian clade. The phylogenetic pattern emerged from the present study is congruent with the known paleo-history of the western Mediterranean basin, with the divergence of the two main Tyrrhenoleuctra lineages corresponding to the split of the Sardo-Corsican microplate from the Iberian block. Vicariance events have characterized the history of this stonefly group along its entire biogeographical history. Surprisingly low evolutionary rates, previously supposed by Fochetti (1991, 1994) and Fochetti et al. (2004) based on nuclear markers (allozymes), have been herein found also in mitochondrial markers. © 2009 Blackwell Verlag GmbH
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
Biochemical systematics, biogeography and evolutionary rates in species of the Mediterranean genus Tyrrhenoleuctra (Plecoptera, Leuctridae)
No full textThe western Mediterranean stonefly genus Tyrrhenoleuctra traditionally includes 3 species: T minuta (Spain, North Africa, Balearic Islands), T tangerina (Spain, North Africa), T zavattarii (Corsica and Sardinia). Since the traditional morphological characters display great and overlapping variation, allozyme electrophoresis was used to clarify taxonomic and phylogenetic relationships within the genus and to discuss biogeographical implications. The results clearly discriminate at least four entities: the Corso-Sardinian unit, for which the name T zavattarii can be used; the Balearic population, representing an undescribed species; at least two Iberian peninsular species. However, more data on topotypic populations are needed to define the taxonomic status of the Iberian species (including definition of the currently used names T minuta and T tangerina). The presence of Tyrrhenoleuctra in Sardinia and Corsica is likely due to an old vicariance event following separation of the Sardinia-Corsica microplate from the Iberian Peninsula. Calibration of the molecular clock (genetic distances vs. Corso-Sardinian plate split from Iberia) resulted in a very low evolutionary rate (0.008 D/my), lower than those found in taxonomically distant groups (including stoneflies) with similar distribution
- …
