1,720,984 research outputs found
Lack of partner preference system for incest avoidance in the bumble bee Bombus terrestris
No full textInbreeding is caused by the mating of closely related individuals and
produces a decrease in the offspring fitness and deleterious consequences for
adults. In haplodiploid social Hymenoptera inbreeding has a further negative effect
because of their particular mechanism of sex determination (sl-CSD), that causes
the emergence, in half of the founded colonies, of unviable or sterile diploid males.
When these males are able to develop until adult stage, as in bumble bees, they
represent a huge cost for the colony. With respect to these high inbreeding
consequences, a selection for mechanisms of inbreeding avoidance would be
expected in bumble bees. Social recognition is one of the most common and
efficient system to avoid inbred mating in social insect, but it is poorly studied in
bumble bees. In this study we investigated the mating choice between siblings or
non-siblings in queens and males of Bombus terrestris reared in laboratory. To
investigate the role of mating behaviour in mating choice, the tests were performed
both in cage and in tunnel. As opposed to what would be expected, we found that
B. terrestris males and gynes do not show a mating preference for non-siblings
compared to siblings (49.3% in non-siblings and 50.7% in siblings) and the mating
latency was even shorter for sibling matings than for non-siblings ones
Integrated conservation of bee pollinators of a rare plant in a protected area near Bologna, Italy
Full text linkAn integrated approach was proposed for the conservation of the bee pollinators of the locally rare plant dittany Dictamnus albus. Based on previous studies that revealed the most efficient pollinators, we performed three related actions to improve their presence in the area: (i) we provided artificial nests for bumblebees and solitary bees; (ii) we added bee plants to support local populations of pollinators throughout their life cycle, and (iii) we reared and released bumblebee colonies from wild queens collected in the area. Artificial nests were occupied at high rates by cavity nesting species such as mason bees, leafcutter bees and carpenter bees, while we did not observe any ground nesting bees. Artificial nests for bumblebees did not attract any wild queens. The bee plants established at different rates: transplanted adult individuals survived better than seeds directly sown at the site. In three consecutive years we reared and released several colonies of buff-tailed bumblebees, which survived through the flowering season but only one developed new gynes
Exploring interaction patterns in plant-pollinator networks across spatial-temporal gradients and under climatic pressures
No full textA fundamental challenge of ecological interaction network analysis is to understand the functioning of communities and the variation of interaction dynamics in space and time and under environmental pressures, such as climatic changes.
Describing spatial-temporal variability of interactions is not straightforward, and despite the increasing interest and amount of literature regarding plant-pollinator network changes across the globe, we are still missing a reliable methodology that allows to compare interaction network structures across environmental and temporal gradients without introducing biases linked to sampling intensity. Moreover, it is difficult to understand how climatic changes can modify plant-pollinator interactions, since experimental studies that consider changes in visitation patterns are still limited.
The aim of this presentation is to navigate across different levels of network complexity to explore:
(1) at the national level – differences in imbalance of degrees between interaction networks along a diversity/environmental gradient (between sites) and within/across the season (months/years);
(2) at the European level – if interaction patterns exist across different biogeographical regions, despite the taxonomic turnover in the composition of the key players, i.e. if different pollinator groups are contributing differently;
(3) under controlled conditions – how warming impacts interaction patterns via physiological and behavioural changes in plant-pollinator communities
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
No evidence for an inbreeding avoidance system in the bumble bee Bombus terrestris
No full textInbreeding is caused by the mating of closely related individuals and may produce a decrease in the fitness of offspring and have deleterious consequences for adults. In haplodiploid social Hymenoptera inbreeding has a further negative effect due to the production of unviable or sterile diploid males. As a consequence, mechanisms of inbreeding avoidance would be expected to evolve. In this study, we investigated the mating choice between related (inbred) or unrelated (outbred) gynes and males of Bombus terrestris reared in laboratory conditions by performing cage and tunnel experiments. Not only did we find no mating preference for related or unrelated partners (mating success 41.55 ± 3.7 and 39.69 ± 4.4%, respectively), but the mating latency was even shorter in inbred (6.97 ± 0.6 min) than in outbred matings (8.74 ± 0.8 min). We hypothesize that in wild populations of B. terrestris, the lack of incest avoidance could be compensated by tolerance of high levels of inbreeding
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