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Group living can be beneficial when individuals reproduce or survive better in the presence of others, but simultaneously there might be costs due to competition for resources. Positive and negative effects on various fitness components might thus counteract each other, so integration is essential to determine their overall effect. Here, we investigated how an integrated fitness measure (reproductive values; RV) based on six fitness components varied with group size among group members in cooperatively-breeding red-winged and superb fairy-wrens (Malurus elegans and M. cyaneus). Despite life historie differences between the species, patterns of RVs were similar, suggesting that the same behavioural mechanisms are important. Group living reduced RVs for dominant males, but for other group members this was only true in large groups. Decomposition analyses showed that our integrated fitness proxy was most strongly affected by group size effects on survival, which was amplified through carry-over effects between years. Our study shows that integrative consideration of fitness components and subsequent decomposition analysis provide much needed insights into the key behavioural mechanisms shaping the costs and benefits of group living. Such attribution is crucial if we are to synthesize the relative importance of the myriad group size costs and benefits currently reported in the literature.
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The Mauritius fruit bat (Pteropus niger) has been the subject of repeated culling campaigns, apparently in response to pressure from the fruit-growing industry concerned over damage to commercially valuable orchard crops such as lychees. More than 31,000 fruit-bearing lychee trees also exist in private backyards making this an issue pertinent to a wide cross-section of the Mauritian general public and not just those involved in commercial fruit production. The level of damage caused by bats to fruit crops is often debated and the low number of robust damage assessment studies hampers mitigation efforts. During the fruiting season of 2016/2017, we assessed the damage among backyard lychee trees attributable to fruit bats and other causes around Vacoas-Phoenix, Central Mauritius and evaluated the impact of using protective netting as a mitigation strategy. Fruit yield from panicles that were protected from depredation by nylon netting was approximately one third greater than that from unprotected panicles. We suspect that fruit bats were responsible for approximately 42% of the total damage but illustrate the difficulties in attributing damage to a single cause in such assessments. Although we demonstrate the value of protective netting we recognize that barriers to implementation exist and that a more holistic approach that incorporates crop protection, forest restoration strategies and addresses negative public attitudes towards bats in general is required to ensure the persistence of this endemic species.
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Background: Effective and cost-effective primary care treatments for low back pain (LBP) are required to reduce the burden of the world’s most disabling condition. This study aimed to compare the clinical effectiveness and cost-effectiveness of the Fear Reduction Exercised Early (FREE) approach to LBP (intervention) with usual general practitioner (GP) care (control). Methods and findings: This pragmatic, cluster-randomised controlled trial with process evaluation and parallel economic evaluation was conducted in the Hutt Valley, New Zealand. Eight general practices were randomly assigned (stratified by practice size) with a 1:1 ratio to intervention (4 practices; 34 GPs) or control group (4 practices; 29 GPs). Adults presenting to these GPs with LBP as their primary complaint were recruited. GPs in the intervention practices were trained in the FREE approach, and patients presenting to these practices received care based on the FREE approach. The FREE approach restructures LBP consultations to prioritise early identification and management of barriers to recovery. GPs in control practices did not receive specific training for this study, and patients presenting to these practices received usual care. Between 23 September 2016 and 31 July 2017, 140 eligible patients presented to intervention practices (126 enrolled) and 110 eligible patients presented to control practices (100 enrolled). Patient mean age was 46.1 years (SD 14.4), and 46% were female. The duration of LBP was less than 6 weeks in 88% of patients. Primary outcome was change from baseline in patient participant Roland Morris Disability Questionnaire (RMDQ) score at 6 months. Secondary patient outcomes included pain, satisfaction, and psychosocial indices. GP outcomes included attitudes, knowledge, confidence, and GP LBP management behaviour. There was active and passive surveillance of potential harms. Patients and outcome assessors were blind to group assignment. Analysis followed intention-to-treat principles. A total of 122 (97%) patients from 32 GPs in the intervention group and 99 (99%) patients from 25 GPs in the control group were included in the primary outcome analysis. At 6 months, the groups did not significantly differ on the primary outcome (adjusted mean RMDQ score difference 0.57, 95% CI −0.64 to 1.78; p = 0.354) or secondary patient outcomes. The RMDQ difference met the predefined criterion to indicate noninferiority. One control group participant experienced an activity-related gluteal tear, with no other adverse events recorded. Intervention group GPs had improvements in attitudes, knowledge, and confidence compared with control group GPs. Intervention group GP LBP management behaviour became more guideline concordant than the control group. In cost-effectiveness, the intervention dominated control with lower costs and higher Quality-Adjusted Life Year (QALY) gains. Limitations of this study were that although adequately powered for primary outcome assessment, the study was not powered for evaluating some employment, healthcare use, and economic outcomes. It was also not possible for research nurses (responsible for patient recruitment) to be masked on group allocation for practices. Conclusions: Findings from this study suggest that the FREE approach improves GP concordance with LBP guideline recommendations but does not improve patient recovery outcomes compared with usual care. The FREE approach may reduce unnecessary healthcare use and produce economic benefits. Work participation or health resource use should be considered for primary outcome assessment in future trials of undifferentiated LBP.
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Alzheimer disease (AD) mortality risk in a large cohort of subjects treated or not with non-steroidal anti-inflammatory drugs (NSAIDs) is unknown. Our objective was to determine whether NSAIDs use is associated with decreased risk of AD mortality. Methods: In this prospective, population-based study (Neurological Disorders in Central Spain [NEDICES]) of 5,072 people without AD (aged 65 years and older), sociodemographic, comorbidity factors, and current medications were recorded at baseline. Community-dwelling older adults were followed for a median of 12.7 years, after which the death certificates of deceased participants were examined. 2,672 (52.7%) of 5,072 participants died, including 504 (18.9%) NSAIDs users and 2,168 (81.1%) non-users. Of the 2,672 deceased participants, 113 (4.2%) had AD as a cause of death (8 [1.6%] among NSAIDs users and 105 [4.8%] among non-users, chi-square = 10.70, p=0.001). In an unadjusted Cox model, risk of AD mortality was decreased in NSAIDs users (hazard ratio [HR] for AD mortality = 0.35, 95% confidence interval [CI] 0.17–0.72, p=0.004) when compared to non-users. After adjusting for numerous demographic factors and co-morbidities, the HR for AD mortality in NSAIDs users was 0.29, 95% CI 0.12–0.73, p=0.009. Stratified analyses showed a significantly decreased risk of AD mortality with aspirin, whereas non-aspirin NSAIDs only showed a statistical trend toward significance in the adjusted Cox regression models. NSAIDs use was associated with 71% decreased risk of AD mortality in older adults. Our results support the hypothesis that NSAIDs use is a protective factor of developing AD.
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Invasive plants may outcompete and replace native plant species through a variety of mechanisms. Recent evidence indicates that soil microbial pathways such as pathogen accumulation may have a considerable role in facilitating competition between native and invasive plants. To assess microbe-mediated pathways of invasion, we tested the impacts of invaded and non-invaded field soils on plant establishment using naturally-occurring populations of the common Eurasian invader Cirsium arvense (Canada thistle) in Southern Ontario, Canada. Linked field and greenhouse experiments were used to quantify differences in the germinability and early growth rates of native plant species, depending on exposure to the microbial community in invaded or non-invaded soils. The invaded microbial community significantly reduced early growth rates for two of the seven native species surveyed, and decreased seed germination for another. In contrast, the germination and growth of invasive Cirsium were not affected by its own soil microbial community. These results demonstrate that the invasion of Cirsium arvense can reduce the performance of some native plant species through changes to the soil microbial community. Different effects on different species suggest this invader may also change the relative importance of certain natives in the invaded community. If these effects influence plant abundance in the field, microbially-mediated interactions in the soil may aid the invasion of Cirsium arvense and facilitate the disruption of invaded communities.
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Large rain events drive dramatic resource pulses and the complex pulse-reserve dynamics of arid ecosystem changes between high-rain years and drought. However, arid-zone animal responses to short-term changes in climate are unknown, particularly smaller rain events that briefly interrupt longer-term drought. Using arthropods as model animals, we determined the effects of a small rain event on arthropod abundance in western NSW, Australia during a longer-term shift towards drought. Arthropod abundance decreased over two years, but captures of ten out of fifteen ordinal groups increased dramatically after the small rain event (<40mm). The magnitude of increases ranged from 10.4 million% (collembolans) to 81% (spiders). After three months, most groups returned to pre-rain abundance. However, small soil-dwelling beetles, mites, spiders, and collembolans retained high abundances despite the onset of winter temperatures and lack of subsequent rain. As predicted by pulse-reserve models, most arid-zone arthropod populations declined during drought. However, small rain events may play a role in buffering some groups from declines during longer-term drought or other xenobiotic influences. We outline the framework for a new model of animal responses to environmental conditions in the arid zone, as some species clearly benefit from rain inputs that do not dramatically influence primary productivity.
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Previous research suggests that judgments about a male speaker’s trustworthiness vary due to the speaker’s voice pitch (mean F0) and differ across domains. Mixed results in terms of the direction and extent of such effects have been reported, however. Moreover, no study so far has investigated whether men’s mean F0 is, indeed, a valid cue to their self-reported and behavioral trustworthiness, and whether trustworthiness judgments are accurate. We tested the relation between mean F0 and actual general, economic and mating-related trustworthiness in 181 men, as well as trustworthiness judgments of 95 perceivers across all three domains. Analyses show that men’s mean F0 is not related to Honesty-Humility (as a trait indicator of general trustworthiness), trustworthy intentions, or trust game behavior, suggesting no relation of mean F0 to general or economic trustworthiness. In contrast, results suggest that mean F0 might be related to mating-related trustworthiness (as indicated by self-reported relationship infidelity). However, lower mean F0 was judged as more trustworthy in economic, but less trustworthy in mating-related domains and rather weakly related to judgments of general trustworthiness. Trustworthiness judgments were not accurate for general or economic trustworthiness, but exploratory analyses suggest that women might be able to accurately judge men’s relationship infidelity based on their voice pitch. Next to these analyses, we report exploratory analyses involving and controlling for additional voice parameters.
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Plant sigma factors (SIGs) are key regulators of chloroplast gene expression and chloroplast differentiation. Despite their functional importance, the evolutionary history of these factors remains unclear. Using newly available genomic and transcriptomic data, we conducted a detailed and comprehensive phylogenetic analysis of SIG homologues from land plants and algae. Our results reveal that plants have acquired sigma factors from ancestor cyanobacteria via endosymbiotic gene transfers, forming four major clades, namely, super-SIG2 (SIG2/3/4/6/SIG2-like), SIG1, SIG5 and SIGX. The super-SIG2 clade was confirmed to have evolved from cyanobacterial SIGA factors, and a novel clade (SIGX) specific to non-angiosperms was revealed here. Gene duplications (mainly whole genome duplications) within lineages and species have contributed to the expansion of sigma factors in plants, especially flowering plants. We hypothesize that plant sigma factors originated from different endosymbiotic ancestors and evolved diverse functions. This not only sheds new light on the evolution of plant SIG genes but also paves the way for understanding the functional diversification of these genes.
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The ongoing and increasing worldwide demand for fish has caused a steady increase in aquaculture production during the last decades. This emphasizes the importance of farming systems with a low ecological footprint, like recirculating aquaculture systems (RAS), which are an alternative to traditional open systems. Furthermore, implementing microalgae treatments in RAS, sustainable water management and low discharge of concentrated wastewater could be achieved, allowing its reuse in the system. The influence of three factors on microalgae treatment efficiency in RAS water were studied: i) microalgae species (Chlorella vulgaris, Tetradesmus obliquus), ii) water pre-treatment (sterile filtration), and iii) sampling location within the RAS (e.g. from fish tank, after UV-disinfection, etc.). To this end, fully factorial, replicated cultivations were carried out in 100-ml flasks, and nutrient removal, microalgae growth, and density of bacteria and protozoa were measured for up to 18 days. Results show that both species are able to grow in RAS water and effectively remove nutrients in it, yet their performance depended greatly on water quality. In sterile RAS water, growth and nutrient removal efficiency of C. vulgaris surpassed that of T. obliquus. In non-sterile RAS water, the pattern reversed because of grazing proto- zoa. The location of sampling within the RAS had no discernible effect on microalgae growth or nutrient removal efficiency. The results confirm that a microalgae-based technology to treat and valorise RAS water is technically feasible, yet caution that inferences made can be reversed depending on the choice of the species and the pre- treatment of the RAS water prior to cultivation.
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The viruses that cause dengue fever, Zika and chikungunya are transmitted by the mosquito, Aedes aegypti and threaten global public health. Current vaccines and treatments against these viruses along with methods of mosquito control are of limited efficacy and novel interventions are needed. Wolbachia are bacteria that inhabit insect cells and have been found to reduce viral infection, a phenotype that is referred to as viral ‘blocking’. Although not naturally found in A. aegypti, Wolbachia were stably introduced into this mosquito in 20115 and have been shown to reduce the transmission potential of dengue, Zika and chikungunya. Trials in the tropics show that Wolbachia can spread through A. aegypti populations and reduce the local incidence of dengue fever. Despite this, the stability of viral blocking over time is unknown. Here, we reveal genes in A. aegypti that appear to affect the strength of Wolbachia-mediated dengue blocking in response to selection. We find that mosquito genotypes associated with weaker dengue blocking have reduced fitness, suggesting that there is potential for blocking to be maintained by selection. These results will inform the use of Wolbachia as biocontrol agents against mosquito-borne viruses and direct further research into measuring and improving their efficacy.
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