1,720,975 research outputs found
How do host plant use and seasonal life cycle relate to insect body size: A case study on European geometrid moths (Lepidoptera: Geometridae)
No full textWe used European geometrid moths (>630 species) as a model group to investigate how life history traits linked to larval host plant use (i.e., diet breadth and host-plant growth form) and seasonal life cycle (i.e., voltinism, overwintering stage and caterpillar phenology) are related to adult body size in holometabolous insect herbivores. To do so, we applied phylogenetic comparative methods to account for shared evolutionary history among herbivore species. We further categorized larval diet breadth based on the phylogenetic structure of utilized host plant genera. Our results indicate that species associated with woody plants are, on average, larger than herb feeders and increase in size with increasing diet breadth. Obligatorily univoltine species are larger than multivoltine species, and attain larger sizes when their larvae occur exclusively in the early season. Furthermore, the adult body size is significantly smaller in species that overwinter in the pupal stage compared to those that overwinter as eggs or caterpillars. In summary, our results indicate that the ecological niche of holometabolous insect herbivores is strongly interrelated with body size at maturity
Are day-flying moths more specialised in larval dietary breadth? – A test of the ‘Salient Aroma Hypothesis’ in a predominantly nocturnal clade
No full textAbstract
Although diurnality is widespread across Lepidoptera and has evolved many times independently, its causes and ecological implications are yet poorly understood. The ‘Salient Aroma Hypothesis’ (SAH) postulates that diurnal insect herbivores are overall more specialised in dietary breadth than species active at night. It is furthermore assumed that diurnality evolved more frequently in species that live in cooler environments. Using European geometrid moths as a model group, we tested whether diurnal activity in adults is associated with an increased larval dietary breadth as predicted by the ‘Salient Aroma Hypothesis.’ We further investigated whether species that exclusively occur in colder regions or whose flight period is restricted to cool seasons are more likely to exhibit a diurnal flight activity. Contrary to expectation, we found no consistent differences in larval dietary breadth between diurnal and nocturnal species, and thus no support for the ‘Salient Aroma Hypothesis.’ Diurnal activity occurred more frequently in species restricted to cold regions, but not in species restricted to cool seasons. We conclude that diurnality could serve as an advantageous adaptation in cold environments, depending on further factors such as resource availability or predation pressure, but has no immediate consequences for larval dietary breadth
Larval diet type and voltinism are linked with adult body size in European Erebidae (Lepidoptera)
No full textAbstract Body size is one of the most characteristic traits of every animal species and strongly influences its ecological niche. Identifying life-history traits that are associated with body size and investigating possible causalities behind such contingencies is thus a central topic in evolutionary ecology. In this study, we examined whether adult body size in Lepidoptera relates with resource type used at larval stage, larval dietary specialisation, voltinism, or adult diel activity. Based on previous findings, we hypothesised that species associated with woody plants are overall larger than those feeding on herbaceous plants or alternative food sources (e.g., lichens, detritus etc.). We further hypothesised that larger body sizes are associated with a lower degree of dietary specialisation, a univoltine life style, and nocturnal activity in adults. To test our hypotheses, we focussed on more than 220 species of European Erebidae moths, one of the taxonomically and ecologically most diverse Lepidoptera families worldwide. Increasing availability of molecular data for this group, coupled with advances in phylogenetic comparative methods, allowed us to study these trait relationships by accounting for shared evolutionary history among species, and– in addition to that– investigate potential causalities driving the detected patterns. We found adult body size to be positively linked with woody plant feeding and a univoltine life cycle, supporting the respective hypothesis. Our results further indicated that resource type affects the evolution of body size, while the latter strongly determines voltinism. Contrary to expectation, body size was neither related with larval dietary specialisation nor with adult diel activity. In conclusion, our study suggests that smaller body sizes, frequently associated with feeding on herbaceous plants or alternative food sources, are of evolutionary advantage as they facilitate the realisation of multiple generations per year and thus allow for faster adaptations to changing environmental conditions
Ecological specialisation and range size determine intraspecific body size variation in a speciose clade of insect herbivores
No full textCaterpillars and Host Plant Records for 59 Species of Geometridae (Lepidoptera) from a Montane Rainforest in Southern Ecuador
No full textDuring four months of field surveys at the Reserva Biológica San Francisco in the south Ecuadorian Andes, caterpillars of 59 Geometridae species were collected in a montane rainforest between 1800 and 2800m altitude and reared to adults. The resulting data on host plant affiliations of these species was collated. The preimaginal stages of 58 and adult stages of all 59 species are depicted in colour plates. Observations on morphology and behaviour are briefly described. Five species, documented for the first time in the study area by means of larval collections, had not been previously collected by intensive light-trap surveys. Together with published literature records, life-history data covers 8.6% of the 1271 geometrid species observed so far in the study area. For 50 species these are the first records of their early stages, and for another 7 the data significantly extend known host plant ranges. Most larvae were collected on shrubs or trees, but more unusual host plant affiliations, such as ferns (6 geometrid species) and lichens (3 geometrid species), were also recorded. Thirty-four percent of the caterpillars were infested by wasp or tachinid parasitoids
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
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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