1,720,960 research outputs found
The onset of fish colonization in a coastal defence structure (Chioggia, Northern Adriatic Sea)
No full textCoastal defence structures constitute the most extensive hard substrates of the Northwestern Adriatic Sea and are known to sustain rich benthic
and nektonic communities. To appreciate the pattern of colonization, we studied the fish assemblage of a recently deployed breakwater. We
compared observations from two years, the different sides (landward and seaward) of the barrier, and the two fringes, characterized by timing of
work completion. The results indicate that colonization, still in process, follows different patterns among species. Benthic and necto-benthic
species presented a striking increase in abundance and richness in the second year of colonization, while more mobile species did not evince
any variation between years. Differences in mobility among species suggest that the latter group may have reached the breakwater from nearby
artificial substrates, whereas the former colonized the new structure as recruits. In addition, fish assemblages differed between the two sides,
likely due to variation in the environmental characteristics, and according to depth, reflecting species preferences
Experimentally induced immune challenge affects male sexual displays in the peacock blenny (Salaria pavo).
No full textMale lagoon gobies, Knipowitschia panizzae, prefer more ornamented to larger females
No full textFemale ornamentation may be directly sexually
selected, by male choice or female competition, or occurs as
the result of a genetic correlation, arising from sexual selection
on males. However, increasing evidence supports the
former hypothesis, suggesting that males actively choose
their partner preferring traits indicative of female quality. In
the lagoon goby, Knipowitschia panizzae, a polygynous
species whose males perform parental care to eggs, body
length and the size of a sex-specific yellow patch on the
belly are known to be reliable indicators of female fecundity.
In this paper, we tested, using dummies, the male’s mating
preferences for female body and yellow belly patch sizes.
The two experimental trials in which a single female trait
was variable showed that males prefer a larger belly patch
and a larger body size, indicating that both these characters
are selected by male mate choice. However, when faced with
dummies exhibiting an inverse combination of body and
belly patch sizes (experiment 3), males significantly preferred
the smaller ones with larger yellow belly patches. A
calculation of dummy theoretical fecundity reveals that in
the first two experiments, males would have received an
immediate benefit from their choice in terms of egg number,
whereas in the third one, males chose partners that would
have provided them with fewer eggs. The male lagoon goby
preference for females with larger belly patches, regardless
of their size, suggests that this trait, in addition to indicating
fecundity, conveys information about other aspects of female
and/or egg quality
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
When fathers make the difference: efficacy of male sexually selected antimicrobial glands in enhancing fish hatching success.
No full textEgg and offspring resistance to pathogens is a major determinant of survival and has been mainly ascribed to maternal factors. However, paternal production of antimicrobials was recently suggested to increase offspring survival in species where males perform egg care. 2. In the peacock blenny, Salaria pavo, a demersal spawning species where males exhibit a pair of anal glands producing lysozyme-like compounds, we tested the antimicrobial activity and the egg protection efficacy of these glands. The anal gland secretion (AGS) has an inhibitory effect on the growth of both Gram-negative and Gram-positive bacteria, including those causing the most severe fish diseases in marine culture. The egg clutches cared for by males deprived of anal glands have a significantly lower survival rate than those cared for by sham-operated males and non-viable eggs showed clear signs of bacterial infection. 3. Anal gland secretion production and its protein content are proportional to gland size. In species where male parental care plays a crucial role in offspring survival, females are expected to assess mates selecting those traits that are reliably associated with parental ability. Hence, we experimentally challenged females with dummy males differing in anal gland size. Females definitely preferred dummy males with larger anal glands, suggesting that their choice is driven by the pursuit of direct fecundity benefits. 4. These findings indicate that antimicrobial production is a crucial component of male parental care. The contribution of antimicrobials to male performance as fathers suggests that the development of traits devoted to this function may influence male attractiveness and be sexually selected
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
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