1,170 research outputs found

    Evolution of virulence: triggering host inflammation allows invading pathogens to exclude competitors.

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    Virulence is generally considered to benefit parasites by enhancing resource-transfer from host to pathogen. Here, we offer an alternative framework where virulent immune-provoking behaviours and enhanced immune resistance are joint tactics of invading pathogens to eliminate resident competitors (transferring resources from resident to invading pathogen). The pathogen wins by creating a novel immunological challenge to which it is already adapted. We analyse a general ecological model of 'proactive invasion' where invaders not adapted to a local environment can succeed by changing it to one where they are better adapted than residents. However, the two-trait nature of the 'proactive' strategy (provocation of, and adaptation to environmental change) presents an evolutionary conundrum, as neither trait alone is favoured in a homogenous host population. We show that this conundrum can be resolved by allowing for host heterogeneity. We relate our model to emerging empirical findings on immunological mediation of parasite competition

    Capturing the moment : understanding embodied interactions in early primary physical education

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    Background: Several studies demonstrate the benefits of understanding explicit and tacit embodied interactions in physical education (PE). However, there is little research that explores the embodied interactions that occur in early primary PE classes (years 1 and 2), where children (are socialized to) embody various body values, attitudes and stigma. We adopted a micro-sociological approach to examine the embodied interactions of a group of early primary school children. The study provides new insight into how primary age children embody the world around them in their PE interactions and the impact this embodiment has on them and on their peers. Purpose: Using a micro-sociological approach, the aim of this study was to examine the embodied interactions of a group of year 1 and 2 children (ages 6–8) in PE classes. Participants and settings: The study was conducted at a public primary school in Australia over a six-month period. The lessons were filmed by the lead author, yielding a total of 12 h and 21 min of footage. Observer XT, a systematic observation programme, was utilized to aid in the coding, management and analysis of observational data, allowing for the creation of multiple coding schemes. Findings: The findings highlighted two distinct themes. First, competition, which involved the constant comparison of performance between the children. Second, skill mastery, which involved the children engaging in acts that displayed their advanced understanding of how to perform certain skills. While the emphasis on competition and skill mastery has been echoed across PE literature, this study showed how those with the most cultural resources (sport experience and physical capital) were able to embody these goals to produce high levels of emotional energy during Interactional Rituals. The findings also indicated the pedagogical implications of these micro-moments. The implementation of an approach characterized by a lack of differentiation and minimal teacher intervention created an environment ripe for embodied engagement in competition and skill mastery. Implications: The micro-sociological approach provided a unique insight into how primary age children are embodying the world around them in their PE interactions and the impact this embodiment is having on themselves and their peers. This approach also provides insight into the pedagogical implications of this embodiment, and highlights the need for more creative and/or student-centred pedagogies in primary PE. © 2020 Association for Physical Education

    Therapy and Long-Term Prophylaxis of Vaccinia Virus Respiratory Infections in Mice with an Adenovirus-Vectored Interferon Alpha (mDEF201)

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    An adenovirus 5 vector encoding for mouse interferon alpha, subtype 5 (mDEF201) was evaluated for efficacy against lethal vaccinia virus (WR strain) respiratory infections in mice. mDEF201 was administered as a single intranasal treatment either prophylactically or therapeutically at doses of 106 to 108 plaque forming units/mouse. When the prophylactic treatment was given at 56 days prior to infection, it protected 90% of animals from death (100% protection for treatments given between 1–49 days pre-infection), with minimal weight loss occurring during infection. Surviving animals re-challenged with virus 22 days after the primary infection were protected from death, indicating that mDEF201 did not compromise the immune response against the initial infection. Post-exposure therapy was given between 6–24 h after vaccinia virus exposure and protection was afforded by a 108 dose of mDEF201 given at 24 h, whereas a 107 dose was effective up to 12 h. Comparisons were made of the ability of mDEF201, given either 28 or 1 day prior to infection, to inhibit tissue virus titers and lung infection parameters. Lung, liver, and spleen virus titers were inhibited to nearly the same extent by either treatment, as were lung weights and lung hemorrhage scores (indicators of pneumonitis). Lung virus titers were significantly (>100-fold) lower than in the placebo group, and the other infection parameters in mDEF201 treated mice were nearly at baseline. In contrast, viral titers and lung infection parameters were high in the placebo group on day 5 of the infection. These results demonstrate the long-acting prophylactic and treatment capacity of mDEF201 to combat vaccinia virus infections

    Developmental Symbiosis Facilitates The Multiple Origins Of Herbivory

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    Developmental bias toward particular evolutionary trajectories can be facilitated through symbiosis. Organisms are holobionts, consisting of zygote‐derived cells and a consortia of microbes, and the development, physiology, and immunity of animals are properties of complex interactions between the zygote‐derived cells and microbial symbionts. Such symbionts can be agents of developmental plasticity, allowing an organism to develop in particular directions. This plasticity can lead to genetic assimilation either through the incorporation of microbial genes into host genomes or through the direct maternal transmission of the microbes. Such plasticity can lead to niche construction, enabling the microbes to remodel host anatomy and/or physiology. In this article, I will focus on the ability of symbionts to bias development toward the evolution of herbivory. I will posit that the behavioral and morphological manifestations of herbivorous phenotypes must be preceded by the successful establishment of a community of symbiotic microbes that can digest cell walls and detoxify plant poisons. The ability of holobionts to digest plant materials can range from being a plastic trait, dependent on the transient incorporation of environmental microbes, to becoming a heritable trait of the holobiont organism, transmitted through the maternal propagation of symbionts or their genes

    Gravel pits support waterbird diversity in an urban landscape

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    We assessed the benefit of 11 gravel pits for the settlement of waterbird communities in an urbanized area lacking natural wetlands. Gravel pits captured 57% of the regional species pool of aquatic birds. We identified 39 species, among which five were regionally rare. We used the Self Organizing Map algorithm to calculate the probabilities of presence of species, and to bring out habitat conditions that predict assemblage patterns. The age of the pits did not correlate with assemblage composition and species richness. There was a positive influence of macrophyte cover on waterbird species richness. Larger pits did not support more species, but species richness increased with connectivity. As alternative wetland habitats, gravel pits are attractive to waterbirds, when they act as stepping stones that ensure connectivity between larger natural and/or artificial wetlands separated in space

    Hierarchy Theory of Evolution and the Extended Evolutionary Synthesis: Some Epistemic Bridges, Some Conceptual Rifts

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    Contemporary evolutionary biology comprises a plural landscape of multiple co-existent conceptual frameworks and strenuous voices that disagree on the nature and scope of evolutionary theory. Since the mid-eighties, some of these conceptual frameworks have denounced the ontologies of the Modern Synthesis and of the updated Standard Theory of Evolution as unfinished or even flawed. In this paper, we analyze and compare two of those conceptual frameworks, namely Niles Eldredge’s Hierarchy Theory of Evolution (with its extended ontology of evolutionary entities) and the Extended Evolutionary Synthesis (with its proposal of an extended ontology of evolutionary processes), in an attempt to map some epistemic bridges (e.g. compatible views of causation; niche construction) and some conceptual rifts (e.g. extra-genetic inheritance; different perspectives on macroevolution; contrasting standpoints held in the “externalism–internalism” debate) that exist between them. This paper seeks to encourage theoretical, philosophical and historiographical discussions about pluralism or the possible unification of contemporary evolutionary biology
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