1,720,962 research outputs found
A preliminary study in the use of RAPD markers in detecting genetic differences in hatching patterns of Chirocephalus diaphanus Prévost, 1803 (Crustacea, Anostraca)
No full textDIVERSITÀ GENETICA E MORFOLOGICA IN POPOLAZIONI CIRCUMMEDITERRANEE DEL GENERE BRANCHIPUS
No full textLarval identification of two syntopic species Branchipus schaefferi and Tanymastix stagnalis (Crustacea, Anostraca) sheds light on their pattern of coexistence.
No full textIn the present study we applied a discriminant function analysis to distinguish two fairy shrimp species, Branchipus schaefferi and Tanymastix stagnalis (Anostraca), co-occurring in Lago dell’Orso in central Italy. Our aim was to obtain information on the pattern of coexistence of these two species to investigate their syntopy since early larval stages. To identify the larvae of the two species we used six discriminant functions, one for each larval stage
considered (nauplius, four metanauplius stages and juvenis), and based on morphometric analyses and
measurements of different traits (thoracic appendages, body length, length of first antenna, length of head,
thorax length and length of furca). The pool was visited at weekly intervals during two time periods for
a total of 4 years (1995–1996 and 2000–2001) and physical and chemical variables (water level, water
and air temperature, pH and conductivity) were recorded. A total of 1067 specimens were collected,
measured and morphometrically identified. B. schaefferi was more abundant and persistent than T.
stagnalis. At any stage, T. stagnalis was bigger than B. schaefferi and this difference may justify niche
differentiation between coexisting species. Difference in size might be linked to difference in life-span as B.
schaefferi reproduced earlier and at a smaller size than T. stagnalis. When the hydroperiod is short, B.
schaefferi might be the only species to produce resting eggs in time for reproduction. On the other hand, T.
stagnalis may have an advantage in the longest hydroperiods. In an ephemeral seasonal pond such as
Lago dell’Orso, coexistence can be fostered and competitive exclusion can be prevented as a result of
seasonal environmental changes
Further evidence of the synonymy between Branchipus schaefferi Fisher, 1834 and B. visnyai Kertés, 1956 (Crustacea, Anostraca)
No full textHabitat disorder: an ecological measure to predict Daphnia sexual reproduction in stochastic environments
No full textThe aim of the present research is to study two cyclic parthenogenetic populations of Daphnia obtusa, occurring in distinct but geographically overlapping ponds. In both populations parthenogenetic eggs were laid continuously throughout the year, showing the typical pattern observed at our latitudes, with two peaks of production in winter and in early spring. On the contrary, the maximum production of resting eggs was not simultaneous in the two biotopes and coincided with the winter peak in one pond and with the spring peak in the other one. To explain this different behaviour, we considered a set of biotic and abiotic factors characteristic of the habitats under study, and found evidences of a link between the annual production of resting eggs and increasing environmental variation
Re-evaluation of three related species of the genus Brachipus Schaeffer, 1766 (Branchiopoda: Anostraca) by morphological and genetic analyses
No full textThe systematics of the genus BranchipusSchaeffer, 1766 (Branchiopoda: Anostraca) has been based on morphological taxonomy only and thus remains poorly resolved or, at best, questionable. Among the seven species described in the genus, a detailed comparison of Branchipus schaefferiFischer, 1834 with both B. pasaiCottarelli, 1969 and B. visnyaiKertész, 1956 is necessary to clarify their status. The use of morphological characters and, in particular, the appearance of second antennae and antennal appendages in males still cause taxonomic confusion among these three species. Herein, we use two molecular markers (allozymes and mtDNA sequences) and scanning electron microscopy to determine consistent differentiation patterns and test for congruence with the shape of the genus diagnostic trait, the frontal shield. We analyzed specimens belonging to 11 populations and covering a wide geographic distribution: B. pasaifrom Italy, B. schaefferifrom Spain and Morocco, and B. visnyaifrom Malta and Italy. The extent of genetic divergence among populations evaluated by allozyme variation at 13 enzymatic loci and a mtDNA marker suggests the existence of different taxa and the absence of gene flow between them. The molecular results, together with morphological observations, did not provide support for the existing subdivision in the three nominal species B. pasai, B. schaefferi, and B. visnyaiand places the validity of previously proposed taxonomic groups in discussio
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
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