1,720,963 research outputs found
Ecological factors associated with pre-dispersal predation of fig seeds and wasps by fig-specialist lepidopteran larvae
Full text linkIn brood pollination mutualisms, predation of developing fruit can have large negative repercussions for both plant and pollinator population dynamics. The Sonoran Desert rock fig Ficus petiolaris and its highly-coevolved wasp pollinator are subject to frequent attack by lepidopteran larvae that consume fig fruit and the developing seeds and larval pollinators they contain. We used generalized linear mixed models to investigate how the phenology, quantity, and spatial distribution of fig fruits is associated with variation in lepidopteran damage intensity on individual trees at nine geographic locations spanning a 741 km latitudinal transect along Mexico’s Baja California Peninsula. We found lepidopteran damage to be strongly positively associated with more synchronous fig crops and larger trees, and only weakly associated with local host tree density. These results imply that fruit production that is asynchronous within trees and spread out over time, as observed in several fig species, benefits female and male components of fitness (pollen disperser and seed production, respectively) by reducing pre-dispersal predation by frugivores.This is a manuscript of an article published as Piatscheck, Finn, Justin Van Goor, Derek D. Houston, and John D. Nason. "Ecological factors associated with pre-dispersal predation of fig seeds and wasps by fig-specialist lepidopteran larvae." Acta Oecologica (2018). doi: 10.1016/j.actao.2018.03.001. Posted with permission.</p
Past, present and future: Geographic and temporal variation in a fig–fig wasp mutualism
Full text linkAll living organisms interact with different degrees of interdependence and in ways that are integral to their ecology and evolution. Of the many forms of species interaction, mutualism is one in which species reciprocally obtain benefits from their interactions. Because mutualism is ubiquitous in nature, mutualists are commonly associated with a broader community of species whose interactions vary across a mutualist–antagonist spectrum and in space and time, and so they play a broadly important role in ecosystem function and species evolution. Flowering plants are widely distributed, typically primary producers, and thus foundational ecosystem elements. They are also ubiquitously associated with a diverse assemblage of insects, including diffuse to species-specific associations with pollinators (mutualists) and herbivores and seed predators (antagonists), which are interactions that effect the reproductive fitness of both plants and insects. The main goal of this dissertation is to investigate the effects of past and current environmental variation on the dynamics of species involved in obligate plant-insect interactions, and to model this dynamic in the context of future climate scenarios. This goal was addressed studying a fig–fig wasp system as a biological model. Fig trees (Ficus, family Moraceae) are a well-known example of obligate symbiosis in which the plants serve as hosts to pollinator and non-pollinator fig wasps and other insects whose larva develop within fig fruits. Ficus petiolaris is a rock-strangler fig tree, endemic to Mexico, and hosts nine species of chalcidoid fig wasps: one pollinator plus eight species of non-pollinators that are antagonistic to the plant, pollinator or both. In addition, F. petiolaris fruit (including developing seeds and wasps) are subject to predation by a species of a lepidopteran larva. Past climatic fluctuations and the geological history of the region are factors that have influenced the co-distribution of these species, a history that can be revealed through the analysis of their contemporary genetic structure. Using single nucleotide polymorphism (SNP) molecular data, population genetics, phylogenetics, and species distribution modeling, I investigated how the geology, geography and historical climate in western Mexico shaped the genetic landscape of F. petiolaris, revealing that northern range limits of F. petiolaris shifted to the south during the late Pleistocene, with subsequent range expansion resulting in a contemporary contact zone in coastal northwestern Mexico between previously isolated populations in Baja California and mainland Mexico. I then investigated present day associations between biotic and abiotic ecological variables and local and landscape-level dynamics in fig wasp community composition and lepidopteran fruit predation. The results indicate that variation in F. petiolaris reproductive phenology and tree density differentially influence the relative proportions of pollinating and parasitic wasps, as well as the rate of damage cause by the lepidopteran larvae. Furthermore, I found that increasing local temperature and precipitation strongly benefit pollinator reproductive success, and hence pollen dispersal, at the expense of non-pollinator production. Finally, global climate change scenarios in Mexico predict substantial near-future geographical changes in temperature and rainfall. Using future climate modeling, I projected the distribution of F. petiolaris and predicted changes in pollinator versus non-pollinator reproductive success to assess implications of climate change for the fig–fig wasp mutualism. Because rapid, human-mediated global environmental change is threatening biodiversity, it is crucial to understand the effect of spatial and temporal environmental variation on species interactions and their consequences. Projections of the F. petiolaris system indicate that near-term climate change has the potential to disadvantage the mutualism by decreasing pollinator reproduction success over an expanded geographical area. This dissertation provides new insight into the fig–fig wasp symbiosis and its relationship with its past and current environment, and present for the first time a joint, climate-based projection of a fig’s geographical distribution, wasp community composition, and mutualism dynamics into the future.</p
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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