1,720,956 research outputs found
Behavioural variation in background colour matching and the effect of social environment in rock-pool mosquitoes
No full textSeveral animal species conceal themselves from potential predators by actively choosing environmental patches that best match body coloration and chromatic patterns. Growing evidence shows that a variety of contexts and conditions can affect this background choice behaviour, yet the extent of this variety remains largely underexplored. Here, we explore the effect of disturbance and social environment on background colour choice behaviour in the rock-pool mosquito Aedes mariae. We exposed single individuals and groups of individuals to experimental arenas made of dark and bright patches and recorded the colour preferences of individuals when alone and within groups, and before and after a disruptive event. We found a marked prevalence of individuals favouring a dark background and an among-individual variation in choice over replicated trials. Moreover, we observed a non-significant effect of disturbance but a significant role of the social environment. In fact, being caged in groups significantly increased the proportion of mosquitoes choosing the dark background. Our results provide strong evidence of a background colour choice in Ae. mariae, a density dependence of this choice, and a non-negligible inter-individual variation in this behaviour. Overall, these findings offer intriguing insights into background choice behavioural variation and flexibility of mosquitoes
Sex-biased phenotypic plasticity affects sexual dimorphism patterns under changing environmental conditions
Full text linkSexual dimorphism is almost ubiquitous in animals. A common pattern observed across multiple taxa involves differences in development time (sexual bimaturism) and body size (sexual size dimorphism) between conspecific males and females. Furthermore, a strict association of dimorphism at these traits has been documented in several taxa, where the sex showing shorter development time also has a smaller body size than the other sex. Growth and development are strongly dependent on environmental conditions during individual life-cycle in ectotherms, inducing considerable phenotypic plasticity. However, how phenotypic plasticity affects the association between sexual dimorphism in development time and body size remains unclear. Here, we tracked development time, body size, and body mass throughout the ontogeny of the mosquito Aedes mariae. The larval development of this species is strictly linked to Mediterranean Sea rock-pools, whose highly variable environmental conditions over minimal time frames make this organism-environment system ideal for exploring plasticity-led eco-evolutionary processes. We found differential plasticity between males and females, dissolving the link between dimorphism in development time and body size under increasing temperature and decreasing salinity conditions. These findings contrast with the current hypotheses proposed to explain the origin of the association between sexual bimaturism and sexual size dimorphism, highlighting the condition dependence of sexual dimorphism patterns and the need to consider phenotypic plasticity in future studies on their evolution
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
Variability in the "stereotyped" prey capture sequence of male cuttlefish (Sepia officinalis) could relate to personality differences
No full textStudies of animal personality have shown consistent between-individual variation in behaviour in many social and non-social contexts, but hunting behaviour has been overlooked. Prey capture sequences, especially in invertebrates, are supposed to be quite invariant. In cuttlefish, the attack includes three components: attention, positioning, and seizure. The previous studies indicated some variability in these components and we quantified it under the hypothesis that it could relate to personality differences. We, therefore, analysed predation sequences of adult cuttlefish to test their association with personality traits in different contexts. Nineteen subjects were first exposed to an "alert" and a "threat" test and then given a live prey, for 10 days. Predation sequences were scored for components of the attack, locomotor and postural elements, body patterns, and number of successful tentacle ejections (i.e. seizure). PCA analysis of predatory patterns identified three dimensions accounting for 53.1%, 15.9%, and 9.6% of the variance and discriminating individuals based on "speed in catching prey", "duration of attack behaviour", and "attention to prey". Predation rate, success rate, and hunting time were significantly correlated with the first, second, and third PCA factors, respectively. Significant correlations between capture patterns and responsiveness in the alert and threat tests were found, highlighting a consistency of prey capture patterns with measures of personality in other contexts. Personality may permeate even those behaviour patterns that appear relatively invariant
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
Plastic Aliens: Developmental Plasticity and the Spread of Invasive Species
No full textBiological invasions are one of the worst threats to biodiversity conservation, ecosystem services and functionality, and human health. However, of the high number of organisms that are transported and introduced outside their native range, only a subset of them can survive, establish and spread in the novel area, becoming invasive. What determines the ability of an alien animal species to become invasive? There is an increasing awareness that the answer to this longstanding and crucial question is highly multifactorial, with some factors already well-discerned, and some not yet elucidated. In this book chapter, we focus on developmental plasticity, the permanent change in the developmental trajectory adopted by an organism in response to gene–environment interactions. Developmental plasticity is an important adaptive response to the obvious variability of biotic and abiotic environmental conditions over time. Yet, it can also promote the invasion of novel habitats, by favouring the optimal match between individual phenotypes and the new environment, during the early steps of an invasion. By relying on the available literature and focusing on animal invasions, we analyse the adaptive advantages conferred by developmental plasticity (i) in dealing with the new biotic and abiotic environment during the stage of introduction, (ii) in terms of reproductive rate and population growth, two crucial processes for overcoming the stages of establishment and (iii) in dispersal traits promoting the spread in the new environment. We conclude that, although acknowledged in previous literature, the actual contribution of developmental plasticity to the shaping of the ideal invader might have been underrated
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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