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Search Results: 1 - 10 of 182155 matches for " Miguel B. Araújo "
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A Regional Climate Study of Heat Waves over the Iberian Peninsula  [PDF]
Hari Prasad Dasari, Isaac Pozo, Francisco Ferri-Yá?ez, Miguel B. Araújo
Atmospheric and Climate Sciences (ACS) , 2014, DOI: 10.4236/acs.2014.45074
Abstract: We present a regional climate simulation for the Iberian Peninsula for a 60-year period (1950-2009) using the WRF-ARW model with a focus on the simulation of summer maximum temperatures and associated extreme heat waves. The WRF model was designed at a 5 km horizontal resolution on a 5-month (May-September) seasonal scale, for every year, during the study period with initial/boundary conditions derived from NCEP 2.5 degree reanalysis. The comparison of simulated mean summer seasonal maximums and mean maximums of June, July, and August months with the corresponding E-OBS data sets indicates that the model is able to characterize the spatial variation of magnitudes of temperature change over the Iberian Peninsula. The mean extreme heat wave conditions during the climate period 1950-2009 are well simulated and match the observations well. The regional scale simulations clearly show the propagation of intense heat waves from the south west to north east of Iberia. The WRF-ARW model also simulated well the general trend of increase in heat waves over most parts of the Iberian Peninsula during the study period 1950-2009. The characteristics of the most severe heat waves years 2003 and 2006 are also well simulated by the model.
The geographic scaling of biotic interactions
Miguel B Araújo,Alejandro Rozenfeld
PeerJ , 2015, DOI: 10.7287/peerj.preprints.82v1
Abstract: A central tenet of ecology and biogeography is that the broad outlines of species ranges are determined by climate, whereas the effects of biotic interactions are manifested at local scales. While the first proposition is supported by ample evidence, the second is still a matter of controversy. To address this question, we develop a mathematical model that predicts the spatial overlap, i.e., co-occurrence, between pairs of species subject to all possible types of interactions. We then identify the scale in which predicted range overlaps are lost. We found that co-occurrence arising from positive interactions, such as mutualism (+/+) and commensalism (+/0), are manifested across scales of resolution. Negative interactions, such as competition (-/-) and amensalism (-/0), generate checkerboard-type co-occurrence patterns that are discernible at finer resolutions. Scale dependence in consumer-resource interactions (+/-) depends on the strength of positive dependencies between species. Our results challenge the widely held view that climate alone is sufficient to characterize species distributions at broad scales, but also demonstrate that the spatial signature of competition is unlikely to be discernible beyond local and regional scales.
Conservation Planning with Uncertain Climate Change Projections
Heini Kujala, Atte Moilanen, Miguel B. Araújo, Mar Cabeza
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0053315
Abstract: Climate change is affecting biodiversity worldwide, but conservation responses are constrained by considerable uncertainty regarding the magnitude, rate and ecological consequences of expected climate change. Here we propose a framework to account for several sources of uncertainty in conservation prioritization. Within this framework we account for uncertainties arising from (i) species distributions that shift following climate change, (ii) basic connectivity requirements of species, (iii) alternative climate change scenarios and their impacts, (iv) in the modelling of species distributions, and (v) different levels of confidence about present and future. When future impacts of climate change are uncertain, robustness of decision-making can be improved by quantifying the risks and trade-offs associated with climate scenarios. Sensible prioritization that accounts simultaneously for the present and potential future distributions of species is achievable without overly jeopardising present-day conservation values. Doing so requires systematic treatment of uncertainties and testing of the sensitivity of results to assumptions about climate. We illustrate the proposed framework by identifying priority areas for amphibians and reptiles in Europe.
Shifting Global Invasive Potential of European Plants with Climate Change
A. Townsend Peterson, Aimee Stewart, Kamal I. Mohamed, Miguel B. Araújo
PLOS ONE , 2008, DOI: 10.1371/journal.pone.0002441
Abstract: Global climate change and invasions by nonnative species rank among the top concerns for agents of biological loss in coming decades. Although each of these themes has seen considerable attention in the modeling and forecasting communities, their joint effects remain little explored and poorly understood. We developed ecological niche models for 1804 species from the European flora, which we projected globally to identify areas of potential distribution, both at present and across 4 scenarios of future (2055) climates. As expected from previous studies, projections based on the CGCM1 climate model were more extreme than those based on the HadCM3 model, and projections based on the a2 emissions scenario were more extreme than those based on the b2 emissions scenario. However, less expected were the highly nonlinear and contrasting projected changes in distributional areas among continents: increases in distributional potential in Europe often corresponded with decreases on other continents, and species seeing expanding potential on one continent often saw contracting potential on others. In conclusion, global climate change will have complex effects on invasive potential of plant species. The shifts and changes identified in this study suggest strongly that biological communities will see dramatic reorganizations in coming decades owing to shifting invasive potential by nonnative species.
The Contribution of Vegetation and Landscape Configuration for Predicting Environmental Change Impacts on Iberian Birds
Maria Trivi?o, Wilfried Thuiller, Mar Cabeza, Thomas Hickler, Miguel B. Araújo
PLOS ONE , 2011, DOI: 10.1371/journal.pone.0029373
Abstract: Although climate is known to be one of the key factors determining animal species distributions amongst others, projections of global change impacts on their distributions often rely on bioclimatic envelope models. Vegetation structure and landscape configuration are also key determinants of distributions, but they are rarely considered in such assessments. We explore the consequences of using simulated vegetation structure and composition as well as its associated landscape configuration in models projecting global change effects on Iberian bird species distributions. Both present-day and future distributions were modelled for 168 bird species using two ensemble forecasting methods: Random Forests (RF) and Boosted Regression Trees (BRT). For each species, several models were created, differing in the predictor variables used (climate, vegetation, and landscape configuration). Discrimination ability of each model in the present-day was then tested with four commonly used evaluation methods (AUC, TSS, specificity and sensitivity). The different sets of predictor variables yielded similar spatial patterns for well-modelled species, but the future projections diverged for poorly-modelled species. Models using all predictor variables were not significantly better than models fitted with climate variables alone for ca. 50% of the cases. Moreover, models fitted with climate data were always better than models fitted with landscape configuration variables, and vegetation variables were found to correlate with bird species distributions in 26–40% of the cases with BRT, and in 1–18% of the cases with RF. We conclude that improvements from including vegetation and its landscape configuration variables in comparison with climate only variables might not always be as great as expected for future projections of Iberian bird species.
Hot research on roasted lizards: warming, evolution and extinction in climate change studies
Francisco Ferri-Yá?ez,Jack P. Hayes,Miguel B. Araújo
Frontiers of Biogeography , 2010,
Respostas termorregulatórias de crian as no exercício em ambiente de calor Respuestas termorreguladoras de ni os en el ejercicio en ambiente de calor Thermoregulatory responses of children exercising in a hot environment
Luis Henrique L. S. Gomes,Miguel Araújo Carneiro-Júnior,Jo?o Carlos B. Marins
Revista Paulista de Pediatria , 2013,
Abstract: OBJETIVO: Revisar as possíveis peculiaridades nos mecanismos biológicos referentes às respostas termorregulatórias e sudorípara específicas no exercício realizado por crian as em ambiente de calor. FONTES DE DADOS: Foi feita uma revis o de 47 artigos publicados entre 1960 e 2011 nas bases de dados eletr nicos MedLine e SciELO Brasil, com a utiliza o dos seguintes descritores: 'crian as', 'calor', 'sudorese', 'termorregula o', 'glandula sudorípara' e 'exercício', sendo usados isoladamente ou em combina o, além de uma tese de doutorado sobre o assunto. SíNTESE DOS DADOS: Em pré-púberes, a taxa de sudorese durante o esfor o é menor em compara o aos adultos. Crian as possuem características termorregulatórias diferenciadas, apresentando um débito de suor por glandula muito menor. A maior raz o entre área de superfície e massa corporal faz com que crian as absorvam mais calor durante o exercício sob estresse térmico, elevando o risco de apresentarem sintomas de hipertermia. O maior fluxo sanguíneo para a pele contribui com um melhor controle da homeostase térmica de crian as. O menor tamanho da glandula, a menor sensibilidade colinérgica, os níveis baixos de catecolaminas circulantes durante o esfor o e a falta de horm nio androgênico explicam a ocorrência da baixa elimina o de suor no exercício realizado por crian as. CONCLUS ES: Crian as exibem glandulas sudoríparas imaturas. Assim, a prática de atividade física combinada a altas temperaturas n o é bem tolerada havendo maior vulnerabilidade às les es térmicas. No calor, deve-se ter um controle rigoroso da ingest o de líquidos e um monitoramento atencioso das condi es climáticas para maior seguran a na prática de exercícios. OBJETIVO: Revisar las posibles peculiaridades en los mecanismos biológicos referentes a las respuestas termorreguladoras y sudorípara específicas en el ejercicio realizado por ni os en ambiente de calor. FUENTES DE DATOS: Se realizó una revisión de 47 artículos publicados entre 1960 y 2011 en las bases de datos electrónicas MedLine y SciELO Brasil, con el uso de los siguientes descriptores: "ni os", "calor", "sudoración", "termorregulación", "glándula sudorípara" y "ejercicio", siendo usados aisladamente o en combinación, además de una tesis doctoral sobre el tema. SíNTESIS DE LOS DATOS: En pre-púberes, la tasa de sudoración durante el esfuerzo es menor en comparación a los adultos. Ni os poseen características termorreguladoras diferenciadas, presentando un débito de sudor por glándula mucho menor. La mayor razón entre área de superficie y masa corporal hace que los ni os absorban
Climate Change, Humans, and the Extinction of the Woolly Mammoth
David Nogués-Bravo,Jesús Rodríguez,Joaquín Hortal,Persaram Batra,Miguel B. Araújo
PLOS Biology , 2012, DOI: 10.1371/journal.pbio.0060079
Abstract: Woolly mammoths inhabited Eurasia and North America from late Middle Pleistocene (300 ky BP [300,000 years before present]), surviving through different climatic cycles until they vanished in the Holocene (3.6 ky BP). The debate about why the Late Quaternary extinctions occurred has centred upon environmental and human-induced effects, or a combination of both. However, testing these two hypotheses—climatic and anthropogenic—has been hampered by the difficulty of generating quantitative estimates of the relationship between the contraction of the mammoth's geographical range and each of the two hypotheses. We combined climate envelope models and a population model with explicit treatment of woolly mammoth–human interactions to measure the extent to which a combination of climate changes and increased human pressures might have led to the extinction of the species in Eurasia. Climate conditions for woolly mammoths were measured across different time periods: 126 ky BP, 42 ky BP, 30 ky BP, 21 ky BP, and 6 ky BP. We show that suitable climate conditions for the mammoth reduced drastically between the Late Pleistocene and the Holocene, and 90% of its geographical range disappeared between 42 ky BP and 6 ky BP, with the remaining suitable areas in the mid-Holocene being mainly restricted to Arctic Siberia, which is where the latest records of woolly mammoths in continental Asia have been found. Results of the population models also show that the collapse of the climatic niche of the mammoth caused a significant drop in their population size, making woolly mammoths more vulnerable to the increasing hunting pressure from human populations. The coincidence of the disappearance of climatically suitable areas for woolly mammoths and the increase in anthropogenic impacts in the Holocene, the coup de grace, likely set the place and time for the extinction of the woolly mammoth.
Equilibrium of Global Amphibian Species Distributions with Climate
Mariana Munguía, Carsten Rahbek, Thiago F. Rangel, Jose Alexandre F. Diniz-Filho, Miguel B. Araújo
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0034420
Abstract: A common assumption in bioclimatic envelope modeling is that species distributions are in equilibrium with contemporary climate. A number of studies have measured departures from equilibrium in species distributions in particular regions, but such investigations were never carried out for a complete lineage across its entire distribution. We measure departures of equilibrium with contemporary climate for the distributions of the world amphibian species. Specifically, we fitted bioclimatic envelopes for 5544 species using three presence-only models. We then measured the proportion of the modeled envelope that is currently occupied by the species, as a metric of equilibrium of species distributions with climate. The assumption was that the greater the difference between modeled bioclimatic envelope and the occupied distribution, the greater the likelihood that species distribution would not be at equilibrium with contemporary climate. On average, amphibians occupied 30% to 57% of their potential distributions. Although patterns differed across regions, there were no significant differences among lineages. Species in the Neotropic, Afrotropics, Indo-Malay, and Palaearctic occupied a smaller proportion of their potential distributions than species in the Nearctic, Madagascar, and Australasia. We acknowledge that our models underestimate non equilibrium, and discuss potential reasons for the observed patterns. From a modeling perspective our results support the view that at global scale bioclimatic envelope models might perform similarly across lineages but differently across regions.
The "boatman's knot": a new option for renal hilum ligation during laparoscopic nephrectomy
Bomfim, Alexandre C.;Andreoni, Cassio;Miotto, Ari;Araújo, Mardhen B.;Ortiz, Valdemar;Figueiredo, Luiz F. Poli de;Srougi, Miguel;
Acta Cirurgica Brasileira , 2005, DOI: 10.1590/S0102-86502005000300012
Abstract: purpose: the authors present and describe an original adaptation for the use of "boatman's knot" in renal vein ligation during laparoscopic nephrectomy. this procedure may replace the need for the endovascular stapler, which is considered the standard of care, but not available in several institutions in brazil. the knot presented is also known as the " pig's knot" in several farms in brazil. methods: fourteen laparoscopic nephrectomies were performed by the same surgeon in a standard fashion in seven female pigs. both the renal artery and vein were ligated using the "boatman's knot" as the only method for hemostasis with conventional intracorporeal technique. two knots were applied in each artery and vein; one knot was tied proximally and the other distally. the vessels were then sectioned in between both knots. this technique is based on the intracorporeal confection of two loops by the right hand pair of dissectors with the help of the left hand. the arteries and the veins were then sectioned and the capability to accomplish full hemostasis was observed. results: all the laparoscopic nephrectomies were performed successfully. the "boatman's knot" was performed by the same surgeon with neither complications nor difficulties during the confection of the knot. in all cases hemostasis was fully achieved using only the "boatman's knot" as the hemostatic method. conclusion: the "boatman's knot" is feasible and safe for hilum control during laparoscopic nephrectomy in pigs and total hemostasis can be achieved using it as the only method of hemostasis. however, the safety and the capacity of others to learn how to apply it should be tested before it may be advised to use it routinely.
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