119 research outputs found

    Diversity and Functional Traits of Lichens in Ultramafic Areas: A Literature Based Worldwide Analysis Integrated by Field Data at the Regional Scale

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    While higher plant communities found on ultramafics are known to display peculiar characteristics, the distinguishability of any peculiarity in lichen communities is still a matter of contention. Other biotic or abiotic factors, rather than substrate chemistry, may contribute to differences in species composition reported for lichens on adjacent ultramafic and non-ultramafic areas. This work examines the lichen biota of ultramafics, at global and regional scales, with reference to species-specific functional traits. An updated world list of lichens on ultramafic substrates was analyzed to verify potential relationships between diversity and functional traits of lichens in different Köppen–Geiger climate zones. Moreover, a survey of diversity and functional traits in saxicolous communities on ultramafic and non-ultramafic substrates was conducted in Valle d’Aosta (North-West Italy) to verify whether a relationship can be detected between substrate and functional traits that cannot be explained by other environmental factors related to altitude. Analyses (unweighted pair group mean average clustering, canonical correspondence analysis, similarity-difference-replacement simplex approach) of global lichen diversity on ultramafic substrates (2314 reports of 881 taxa from 43 areas) displayed a zonal species distribution in different climate zones rather than an azonal distribution driven by the shared substrate. Accordingly, variations in the frequency of functional attributes reflected reported adaptations to the climate conditions of the different geographic areas. At the regional scale, higher similarity and lower species replacement were detected at each altitude, independent from the substrate, suggesting that altitude-related climate factors prevail over putative substrate–factors in driving community assemblages. In conclusion, data do not reveal peculiarities in lichen diversity or the frequency of functional traits in ultramafic areas

    Climatic predictors of species distributions neglect biophysiologically meaningful variables

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    This is the final version. Available on open access from Wiley via the DOI in this record.Aim: Species distribution models (SDMs) have played a pivotal role in predicting how species might respond to climate change. To generate reliable and realistic predictions from these models requires the use of climate variables that adequately capture physiological responses of species to climate and therefore provide a proximal link between climate and their distributions. Here, we examine whether the climate variables used in plant SDMs are different from those known to influence directly plant physiology. Location: Global. Methods: We carry out an extensive, systematic review of the climate variables used to model the distributions of plant species and provide comparison to the climate variables identified as important in the plant physiology literature. We calculate the top ten SDM and physiology variables at 2.5 degree spatial resolution for the globe and use principal component analyses and multiple regression to assess similarity between the climatic variation described by both variable sets. Results: We find that the most commonly used SDM variables do not reflect the most important physiological variables and differ in two main ways: (i) SDM variables rely on seasonal or annual rainfall as simple proxies of water available to plants and neglect more direct measures such as soil water content; and (ii) SDM variables are typically averaged across seasons or years and overlook the importance of climatic events within the critical growth period of plants. We identify notable differences in their spatial gradients globally and show where distal variables may be less reliable proxies for the variables to which species are known to respond. Main conclusions: There is a growing need for the development of accessible, fine-resolution global climate surfaces of physiological variables. This would provide a means to improve the reliability of future range predictions from SDMs and support efforts to conserve biodiversity in a changing climate

    Early inhaled budesonide for the prevention of bronchopulmonary dysplasia

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    BACKGROUND Systemic glucocorticoids reduce the incidence of bronchopulmonary dysplasia among extremely preterm infants, but they may compromise brain development. The effects of inhaled glucocorticoids on outcomes in these infants are unclear. METHODS We randomly assigned 863 infants (gestational age, 23 weeks 0 days to 27 weeks 6 days) to early (within 24 hours after birth) inhaled budesonide or placebo until they no longer required oxygen and positive-pressure support or until they reached a postmenstrual age of 32 weeks 0 days. The primary outcome was death or bronchopulmonary dysplasia, confirmed by means of standardized oxygen-saturation monitoring, at a postmenstrual age of 36 weeks. RESULTS A total of 175 of 437 infants assigned to budesonide for whom adequate data were available (40.0%), as compared with 194 of 419 infants assigned to placebo for whom adequate data were available (46.3%), died or had bronchopulmonary dysplasia (relative risk, stratified according to gestational age, 0.86; 95% confidence interval [CI], 0.75 to 1.00; P = 0.05). The incidence of bronchopulmonary dysplasia was 27.8% in the budesonide group versus 38.0% in the placebo group (relative risk, stratified according to gestational age, 0.74; 95% CI, 0.60 to 0.91; P = 0.004); death occurred in 16.9% and 13.6% of the patients, respectively (relative risk, stratified according to gestational age, 1.24; 95% CI, 0.91 to 1.69; P = 0.17). The proportion of infants who required surgical closure of a patent ductus arteriosus was lower in the budesonide group than in the placebo group (relative risk, stratified according to gestational age, 0.55; 95% CI, 0.36 to 0.83; P = 0.004), as was the proportion of infants who required reintubation (relative risk, stratified according to gestational age, 0.58; 95% CI, 0.35 to 0.96; P = 0.03). Rates of other neonatal illnesses and adverse events were similar in the two groups. CONCLUSIONS Among extremely preterm infants, the incidence of bronchopulmonary dysplasia was lower among those who received early inhaled budesonide than among those who received placebo, but the advantage may have been gained at the expense of increased mortality

    Can the intake of antiparasitic secondary metabolites explain the low prevalence of hemoparasites among wild Psittaciformes?

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    Background: Parasites can exert selection pressure on their hosts through effects on survival, on reproductive success, on sexually selected ornament, with important ecological and evolutionary consequences, such as changes in population viability. Consequently, hemoparasites have become the focus of recent avian studies. Infection varies significantly among taxa. Various factors might explain the differences in infection among taxa, including habitat, climate, host density, the presence of vectors, life history and immune defence. Feeding behaviour can also be relevant both through increased exposure to vectors and consumption of secondary metabolites with preventative or therapeutic effects that can reduce parasite load. However, the latter has been little investigated. Psittaciformes (parrots and cockatoos) are a good model to investigate these topics, as they are known to use biological control against ectoparasites and to feed on toxic food. We investigated the presence of avian malaria parasites (Plasmodium), intracellular haemosporidians (Haemoproteus, Leucocytozoon), unicellular flagellate protozoans (Trypanosoma) and microfilariae in 19 Psittaciformes species from a range of habitats in the Indo-Malayan, Australasian and Neotropical regions. We gathered additional data on hemoparasites in wild Psittaciformes from the literature. We considered factors that may control the presence of hemoparasites in the Psittaciformes, compiling information on diet, habitat, and climate. Furthermore, we investigated the role of diet in providing antiparasitic secondary metabolites that could be used as self-medication to reduce parasite load. Results: We found hemoparasites in only two of 19 species sampled. Among them, all species that consume at least one food item known for its secondary metabolites with antimalarial, trypanocidal or general antiparasitic properties, were free from hemoparasites. In contrast, the infected parrots do not consume food items with antimalarial or even general antiparasitic properties. We found that the two infected species in this study consumed omnivorous diets. When we combined our data with data from studies previously investigating blood parasites in wild parrots, the positive relationship between omnivorous diets and hemoparasite infestation was confirmed. Individuals from open habitats were less infected than those from forests. Conclusions: The consumption of food items known for their secondary metabolites with antimalarial, trypanocidal or general antiparasitic properties, as well as the higher proportion of infected species among omnivorous parrots, could explain the low prevalence of hemoparasites reported in many vertebrates

    Modelling the potential impacts of climate change on the hydrology of the Aipe river basin in Huila, Colombia

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    [EN] The dynamics of a global world, and humans performing as a new geological force, require that an effort is undertaken to make robust decisions in order to devise strategies for the management and adaptation to climate change. This study aims to investigate the potential impact of climate change on the hydrology of the Aipe river basin in Huila, Colombia. The abcd Thomas model (four parameters) was calibrated and validated for the stream flows of the Aipe catchment (1992¿2012). The sensitivity and identifiability of the parameters were evaluated using the Monte Carlo Analysis Toolbox (MCAT). The results show the ability of the model to simulate the monthly stream flow (Nash¿Sutcliffe efficiency coefficient of 0,89). The most influential parameters are: a (water storage in the soil) and c (contribution to the aquifer). From the simulated scenarios, the baseline (1992¿2012) was estimated to be an average flow of 15,44 m3s¿1; the trend extrapolation scenario estimated a rate 13,79 m3s¿1 (¿10,64%); while for the multi-model assembly scenario it was 9,34 m3s¿1 (¿39,47%) and for the A2 scenario it was 5,74 m3s¿1 (¿62,60%). Lastly, we propose a set of strategies for adaptation to climate change that are committed to the integral management of water resources.[ES] La dinámica de un mundo global y el hombre como nueva fuerza geológica plantean la necesidad de tomar decisiones robustas, diseñar estrategias de manejo y de adaptarse al cambio climático. Este estudio investiga la respuesta hidrológica de la cuenca hidrográfica del río Aipe (688.9 km2 ), en Huila, Colombia, en acorde con los escenarios de cambio climático desde 2011 a 2040. El modelo hidrológico abcd de Thomas (4 parámetros) fue calibrado y validado comparando el caudal simulado y lo observado en el punto de cierre de la cuenca (en la estación Puente Carretera), usando series históricas mensuales (1992¿2012). Realizamos la evaluación de la sensibilidad e identificabilidad de los parámetros con la herramienta `Monte Carlo Analysis Toolbox¿ (MCAT). Los resultados muestran que el modelo es capaz de representar adecuadamente los caudales mensuales observados en el punto de desagüe de la cuenca, al encontrarse un índice de eficiencia de Nash¿Sutcliffe (NSE) de 0,89. Los parámetros más influyentes son a (almacenamiento del agua en el suelo) y c (aporte al acuífero). Con respecto a la simulación de los escenarios, la línea base (1992¿2012) estimó un caudal medio de 15,44 m3 s ¿1 ; el escenario de extrapolación de tendencias estimó un caudal de 13,79 m3 s ¿1 (¿10,64%); el escenario de ensamble multi-modelo de 9,34 m3 s ¿1 (¿39,47%) y el escenario A2 de 5,74 m3 s ¿1 (¿62,60%). Proponemos una batería de medidas de adaptación al cambio climático que buscan la gestión integral del recurso hídrico.Romero-Cuellar, J.; Buitrago-Vargas, A.; Quintero-Ruiz, T.; Francés, F. (2018). Simulación hidrológica de los impactos potenciales del cambio climático en la cuenca hidrográfica del río Aipe, en Huila, Colombia. RIBAGUA - Revista Iberoamericana del Agua. 5(1):63-78. https://doi.org/10.1080/23863781.2018.1454574S63785

    Factors driving the abundance of Ixodes ricinus ticks and the prevalence of zoonotic I. ricinus-borne pathogens in natural foci

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    Environmental factors may drive tick ecology and therefore tick-borne pathogen (TBP) epidemiology, which determines the risk to animals and humans of becoming infected by TBPs. For this reason, the aim of this study was to analyze the influence of environmental factors on the abundance of immature-stage Ixodes ricinus ticks and on the prevalence of two zoonotic I. ricinus-borne pathogens in natural foci of endemicity. I. ricinus abundance was measured at nine sites in the northern Iberian Peninsula by dragging the vegetation with a cotton flannelette, and ungulate abundance was measured by means of dung counts. In addition to ungulate abundance, data on variables related to spatial location, climate, and soil were gathered from the study sites. I. ricinus adults, nymphs, and larvae were collected from the vegetation, and a representative subsample of I. ricinus nymphs from each study site was analyzed by PCR for the detection of Borrelia burgdorferi sensu lato and Anaplasma phagocytophilum DNA. Mean prevalences of these pathogens were 4.0% +/- 1.8% and 20.5% +/- 3.7%, respectively. Statistical analyses confirmed the influence of spatial factors, climate, and ungulate abundance on I. ricinus larva abundance, while nymph abundance was related only to climate. Interestingly, cattle abundance rather than deer abundance was the main driver of B. burgdorferi sensu lato and A. phagocytophilum prevalence in I. ricinus nymphs in the study sites, where both domestic and wild ungulates coexist. The increasing abundance of cattle seems to increase the risk of other hosts becoming infected by A. phagocytophilum, while reducing the risk of being infected by B. burgdorferi sensu lato. Controlling ticks in cattle in areas where they coexist with wild ungulates would be more effective for TBP control than reducing ungulate abundance.Peer reviewedVeterinary Pathobiolog
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