1,721,128 research outputs found
Contribution to the knowledge of Tunisian amphibians: notes on distribution, habitat features and breeding phenology
No full textIn order to improve the knowledge on amphibian fauna in Tunisia, about 300 water bodies belonging to different habitat typologies were sampled during the period 2004-2008. At the sites where amphibians were observed, we recorded the UTM coordinates, the altitude, and the following environmental features: habitat typology, hydroperiod, electric conductivity, temperature, water turbidity, and macrophyte coverage. The presence of the seven species currently known with certainty for Tunisia has been confirmed: Pleurodeles nebulosus, Discoglossus pictus, Bufo bufo, B. mauritanicus, B. boulengeri, Hyla meridionalis and Pelophylax saharicus. Conversely, no evidence on the occurrence of Salamandra algira in Tunisia, currently considered as doubtful, was collected. Furthermore, all the information available in the literature has been summarized and original data on distribution ranges, breeding phenology and habitat features of the observed species are reported; in particular, the first data on the ecology of the poorly known Pleurodeles nebulosus are provided. Present work represents a contribution towards the realization of an extensive atlas of Tunisian amphibian fauna to be used as a management tool for the conservation of Tunisian inland waters and their biota
A Contribution to the knowledge of Tunisian "large branchiopods" (Branchiopoda: Anostraca, Notostraca, Spinicaudata)
No full textContribute to the knowledge of Tunisian amphibians: Notes on distribution, habitat features and phenology
No full textThe recent non-marine ostracods of tunisia: An updated checklist with remarks on their regional distribution patterns and ecological preferences
Full text linkDifferent lines of investigation have recently contributed to increasing the available knowledge about the invertebrates inhabiting inland waters of north Africa, but a comprehensive synopsis on Tunisian Ostracoda is missing to date. An updated checklist of Recent non-marine ostracods from Tunisia and data on their distribution is thus offered here, representing the most extensive survey on this crustacean group ever carried out in inland waters throughout the country. One-hundred-five sites covering various climate zones, from Mediterranean to desert areas, were sampled between 2002 and 2012. Most of the considered water bodies were temporary or ephemeral habitats, but a few permanent sites were sampled as well. Overall, 18 genera and 32 taxa of putative species rank were collected in the frame of this survey, among which nine species and five genera were new to Tunisian fauna. As a result of this study and based on pre-vious investigations, nine families (Candonidae, Cyprididae, Cytherideidae, Darwinulidae, Ilyocyprididae, Leptocytheridae, Limno-cytheridae, Loxoconchidae, Paradoxostomatidae), 29 genera and at least 45 species of non-marine ostracods are currently known for Tunisia, which thus prove to host the most diverse ostracod fauna among north African countries. The number of species occurring in a single sample varied from 1 to 4. The Eucypris virens complex was the most widespread taxon (58 records), followed by Heterocypris barbara (30 records), Heterocypris incongruens (22 records), and Sarscypridopsis aculeata (16 records). For some ostracod species, clear distributional gradients associated with different climatic conditions were observed. The affinities with adjacent Maghrebian os-tracod faunas are discussed. This study confirms the crucial role played by marginal aquatic habitats for the conservation of biodiversity, in particular in arid and semi-arid regions
Nuovi dati sulla fauna a "grandi branchiopodi" (Branchiopoda: Anostraca, Notostraca, Spinicaudata) delle acque temporanee della Tunisia
No full textNonostante i primi studi sulla fauna a grandi branchiopodi (Anostraca, Notostraca e Spinicaudata) della Tunisia risalgano alla fine del XIX secolo, ad oggi non esiste un inventario completo ed aggiornato di questi organismi nella regione. Al fine di fornire un quadro organico e quanto più possibile completo, una serie di campagne di campionamento sono state condotte a partire dal 2004. Circa 240 corpi idrici temporanei, distribuiti in tutto il territorio Tunisino e nelle sue isole maggiori (Kerkennah e Djerba), sono stati campionati ripetutamente in inverno e primavera e sono stati raccolti dati sulla morfometria dei bacini e sulle principali caratteristiche fisiche e chimiche delle acque. Gli organismi raccolti sono stati identificati sulla base delle loro caratteristiche morfologiche. Le specie Triops cancriformis e Triops mauritanicus simplex, in assenza di dati morfologici affidabili che ne consentano l’identificazione, sono state separate comparando frammenti 12S e/o 16S di rDNA. La significatività dello sforzo di campionamento è stata valutata utilizzando il programma EstimateS 8.2 e le relazioni tra la distribuzione delle specie e le principali variabili ambientali sono state analizzate tramite CCA. In totale sono state identificate 14 specie suddivisibili in 3 gruppi ecologici principali: specie tipiche delle regioni steppiche e subdesertiche (Tanymastigites perrieri, Triops granarius e Leptestheria mayeti), specie tipiche delle regioni umide (Chirocephalus diaphanus, Lepidurus apus lubbocki e Cyzicus tetracerus) e specie alofile (Artemia salina, Phallocryptus spinosus e Branchinectella media). I Notostraci presentano peraltro una netta segregazione latitudinale, con Lepidurus apus lubbocki confinato nelle regioni più umide nel nord del paese e Triops cancriformis, T. mauritanicus simplex T. granarius progressivamente distribuiti lungo un transetto nord-sud. Le specie Branchipus schaefferi e Streptocephalus torvicornis non mostrano chiari pattern di distribuzione geografica e sono presenti dal Sahel alla piana di Medjerda e fino alla penisola di Cap Bonn nel nord della Tunisia. Sebbene le analisi effettuate dimostrino che lo sforzo di campionamento sin ora condotto possa considerarsi esaustivo per la regione, alcune specie nuove per la Tunisia potrebbero essere presenti in pozze temporanee, difficilmente raggiungibili, localizzate lungo i confini Algerino e Libico
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
The role of spatial and environmental factors as determinants of large branchiopod distribution in Tunisian temporary ponds
Full text linkThe influence of spatial and environmental factors in explaining the structure of large branchiopod assemblages at different spatial scales is still poorly explored. We hypothesized that the extent of actual spatial connectivity, and thus the spatial distribution of a metacommunity, may depend on the environmental conditions as represented by climatic gradients and the structural characteristics of the landscape. To test this hypothesis, the distributional patterns of 14 large branchiopod species in a set of 177 temporary water bodies repeatedly sampled across Tunisia and on its main islands were analysed. Physical, chemical, morphological and climatic characteristics of the studied water bodies were collected as well, and spatial structures were described using distance-based Moran’s Eigenvector Maps. Distance-based Redundancy Analysis and variance partitioning explained more than one-half of total variation. Mantel’s autocorrelograms demonstrated that species composition was spatially autocorrelated at shorter distances in the Mediterranean part of the country than in the southern, more arid part. These results suggest that both dispersal limitation and species response to spatially structured environmental gradients might be involved in determining large branchiopod distribution in Tunisia and that these patterns may greatly vary on a regional basis
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