1,721,049 research outputs found
Perpetuation of avian influenza in the Americas: Examining the role of shorebirds in Patagonia
Full text linkAquatic birds are considered the natural reservoir of all influenza viruses (Webster et al. 1992). Low-pathogenic avian influenza (AI) viruses have been isolated from Anseriformes (at least 36 species of ducks and 8 species of geese), Charadriiformes (10 species of shorebirds, 9 species of terns), and a few additional waterfowl species (Olsen et al. 2006).Fil: Escudero, Graciela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; ArgentinaFil: Munster, Vincent J.. Erasmus University Medical Center; Países BajosFil: Bertellotti, Néstor Marcelo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; ArgentinaFil: Edelaar, Pim. Uppsala University. Department of Animal Ecology; Sueci
Probable first record of a drinking seedsnipe (Family Thinocoridae) in the wild
Full text linkSeedsnipes (family Thinocoridae, genera Attagis and Thinocorus with two species each) are strictly vegetarian shorebirds occurring in some of the coldest and driest habitats of southern South America. It has been hypothesised that they retrieve all their water from their food, mostly leaves and buds from (succulent) plants. According to Fjeldså (1996), none of the seedsnipes “are known to drink in natural conditions. However, they may do so in captivity.” In apparent contradiction, he also shows a photograph of a male Greybreasted seedsnipe Thinocorus orbignyianus leaning over at the edge of a pond suggesting that it may have been drinking. Therefore it is not completely sure if drinking in the wild never occurs.Fil: Edelaar, Pim. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; Argentina. Leiden University; Países BajosFil: Torres Dowdall, Julián Roberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Centro de Zoología Aplicada; ArgentinaFil: Abril, Mónica. Universidad Nacional de la Patagonia. Facultad de Ciencias Naturales. Departamento de Biología; Argentin
Sexual selection may not often reduce gene flow between locally adapted populations : a review of some evidence, and suggestions for better tests
No full textSexually selected traits often depend on an individual’s physical condition, or otherwise indirectly reflect the ecological performance of individuals. When individuals disperse between populations that are locally adapted to different environments, their ecological performance may decline. This in turn may result in more poorly expressed sexual traits, and therefore in a lower reproductive success. Hence, sexual selection may reduce the effective gene flow between populations, and thereby maintain or even enhance population divergence. This hypothesis was published in a highly visible journal (van Doorn et al., 2009, Science). Here I review the subsequently published empirical tests of this hypothesis. I downloaded all metadata (incl. abstracts) of papers citing van Doorn et al. (2009) and read those papers that undertook relevant tests. To my surprise, only very few papers provided explicit tests of the hypothesis, this never involved plants, and only one study found support for it. While sexual selection may therefore not often reduce gene flow between locally adapted populations, some improvements to experimental design and choice of study system are noted. I therefore also provide a detailed list of suggestions for high quality tests of this hypothesis. This hopefully acts as a catalyst for more and better studies to test whether sexual and natural selection can work in synergy to reduce effective dispersal, and thereby protect and promote adaptive population divergence
Rediscovery of a second kind of crossbill for the Himalayan region, and the hypothesis that ecological opportunity drives crossbill diversification
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Comment on >evolutionary trade-offs, pareto optimality, and the geometry of phenotype space>
No full textShoval et al. (Reports, 1 June 2012, p. 1157) showed how configurations of phenotypes may identify tasks that trade off with each other, using randomizations assuming independence of data points. I argue that this assumption may not be correct for most and possibly all examples and led to pseudoreplication and inflated significance levels. Improved statistical testing is necessary to assess how the theory applies to empirical data.Peer Reviewe
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
Evidence that helping at the nest does not result in territory inheritance in the Seychelles warbler
Full text linkIn an environment that has a shortage of territories, helping to rear younger siblings (`alloparenting') is proposed to facilitate territory acquisition in two ways: (i) through group augmentation that leads to an increase of the territory with subsequent partial inheritance (budding); and (ii) through site dominance that leads to greater success when competing for the natal or a nearby territory after the death of the territory owner (complete territory inheritance). Most young Seychelles warbler (Acrocephalus sechellensis) males either show alloparenting or budding behaviour. Future budders had significantly more aggressive interactions with neighbours and assisted their parents more with territory defence than similarly aged future alloparents or non-helpers. This led to an increase of the natal territory of future budders before actual budding took place, whereas the natal territories of future alloparents remained constant in size. Alloparents never became budders and vice versa, refuting partial inheritance as an advantage of alloparenting. Natural male breeding vacancies were never inherited by alloparents born on vacant or other territories, but were inherited by budders born on the vacant territory or, if these were absent, predominantly by budders from neighbouring territories. We offer explicit experimental evidence against the `helping at the nest to inherit' hypothesis. Experimentally created male breeding vacancies, with both a male alloparent and a similarly aged sibling budder present simultaneously in the vacant territory, were filled by budders only. Site dominance over territory inheritance is linked to budding and not to alloparenting.
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