Modelado de los factores ambientales que determinan la distribución de especies sinantrópicas de physalis

Modelado de la distribución de especies sinantrópicas de Physalis. Lugares con distribución potencial y real de especies de Physalis (tomatillos)El modelado de la distribución de especies sinantrópicas (malezas) y los factores ambientales que determinan dicha distribución han sido poco estudiados. Physalis tiene 90 especies distribuidas en las Américas, y algunas especies en el Viejo Mundo. México alberga cerca de 70 especies y aproximadamente 35 son endémicas. La sección Angulatae incluye diez especies, todas sinantrópicas en mayor o menor grado. Las especies se concentran en la Sierra Madre Occidental, la Sierra Madre del Sur y en la Faja Volcánica Transmexicana. El objetivo de este trabajo fue modelar e identifi car las variables ambientales que determinan la distribución potencial de las diez especies de Physalis sección Angulatae. Se emplearon 524 registros revisados por especialistas en la taxonomía del grupo y 20 variables ambientales; de éstas 12 fueron climáticas, tres edáfi cas, dos de cobertura de la vegetación y tres de atributos topográfi cos. Los modelos se calcularon con el algoritmo Maxent. Los resultados del modelado mostraron que el hábitat más adecuado para la persistencia de ocho especies se defi nió por el índice normalizado diferencial de vegetación en los meses secos del año, la materia orgánica del suelo, la altitud y el aspecto, las cuales en conjunto explicaron entre el 73 y el 91 % de la variación en su distribución. Otros factores como la precipitación total anual y la isotermalidad determinaron la distribución de P. crassifolia y de P. glabra, respectivamente. El índice normalizado diferencial de la vegetación y las propiedades de los suelos, son predictores determinantes en la distribución potencial de las especies de la sección Angulatae. Palabras clave: máxima entropía, predictores ambientales, sección Angulatae, tomatillos. Abstract: The modeling of the distribution of synanthropic (weedy) species and the environmental factors that determine their distribution is not well studied. Physalis has 90 species distributed in the Americas, and several in the Old World. Mexico harbors about 70 species and approximately 35 are endemic. The section Angulatae includes 10 species, all synanthropic to some degree. The species tended to concentrate in the Sierra Madre Occidental, the Sierra Madre del Sur, and the Transmexican Volcanic Belt. The aim of this work was to model and identify the environmental variables that determine the potential distribution of the ten species of Physalis sect. Angulatae. A total of 524 records that had been verifi ed by the taxonomic experts of the group and 20 environmental variables were used; 12 were climatic, and the other eight were novel and of different types: three soil properties, two normalized differential vegetation indexes and three topographic attributes. The models were obtained with the Maxent algorithm. The results of the modelling showed that the most suitable habitat for the persistence of eight species was delimited by the normalized differential vegetation index during the dry months of the year, the soil organic matter, the elevation and the aspect, which together explained between the 73 and 91 % of the variation in its distribution. Other groups of factors like total precipitation and isthermality determined the distribution of P. crassifolia and P. glabra, respectively. We show that the novel environmental factors such as the normalized differential vegetation index and the soil properties were decisive predictors in the potential distribution of the species in the section Angulatae.Conacy

Dendrochronological Reconstruction Of Environmental History Of Fagus Grandifolia Subsp Mexicana In Mexico

Growth-ring analysis is a valuable source of information for reconstructing environmental history. In this study, ring-width series of a sample of Fagus grandifolia subsp. mexicana were used to identify the main events that have affected populations of this species. Core samples were extracted in three representative beech forests in Mexico. These are forests where F. grandifolia subsp. mexicana dominates the canopy. A total of 3355 years of growth rings were measured and three ring-width chronologies were generated. Average annual ring widths were similar between the three sites and ranged from 0.98 to 1.08 mm. A pattern of multiple suppressions and releases was observed, mainly associated with local events, but with a slight climatic influence. Correlations between the ring-width index and climate variables were not statistically significant, with the exception of a seasonal January-June precipitation pattern (1982-2001). There has not been a large-scale disturbance of natural or human origin in the beech forests of the state of Hidalgo in the past 150 years, except in El Gosco, where anthropogenic disturbances have increased in the past decade.This item is part of the Tree-Ring Research (formerly Tree-Ring Bulletin) archive. For more information about this peer-reviewed scholarly journal, please email the Editor of Tree-Ring Research at [email protected]

Evaluation of a quality improvement intervention to reduce anastomotic leak following right colectomy (EAGLE): pragmatic, batched stepped-wedge, cluster-randomized trial in 64 countries

Background Anastomotic leak affects 8 per cent of patients after right colectomy with a 10-fold increased risk of postoperative death. The EAGLE study aimed to develop and test whether an international, standardized quality improvement intervention could reduce anastomotic leaks. Methods The internationally intended protocol, iteratively co-developed by a multistage Delphi process, comprised an online educational module introducing risk stratification, an intraoperative checklist, and harmonized surgical techniques. Clusters (hospital teams) were randomized to one of three arms with varied sequences of intervention/data collection by a derived stepped-wedge batch design (at least 18 hospital teams per batch). Patients were blinded to the study allocation. Low- and middle-income country enrolment was encouraged. The primary outcome (assessed by intention to treat) was anastomotic leak rate, and subgroup analyses by module completion (at least 80 per cent of surgeons, high engagement; less than 50 per cent, low engagement) were preplanned. Results A total 355 hospital teams registered, with 332 from 64 countries (39.2 per cent low and middle income) included in the final analysis. The online modules were completed by half of the surgeons (2143 of 4411). The primary analysis included 3039 of the 3268 patients recruited (206 patients had no anastomosis and 23 were lost to follow-up), with anastomotic leaks arising before and after the intervention in 10.1 and 9.6 per cent respectively (adjusted OR 0.87, 95 per cent c.i. 0.59 to 1.30; P = 0.498). The proportion of surgeons completing the educational modules was an influence: the leak rate decreased from 12.2 per cent (61 of 500) before intervention to 5.1 per cent (24 of 473) after intervention in high-engagement centres (adjusted OR 0.36, 0.20 to 0.64; P < 0.001), but this was not observed in low-engagement hospitals (8.3 per cent (59 of 714) and 13.8 per cent (61 of 443) respectively; adjusted OR 2.09, 1.31 to 3.31). Conclusion Completion of globally available digital training by engaged teams can alter anastomotic leak rates. Registration number: NCT04270721 (http://www.clinicaltrials.gov)

Evaluation of a quality improvement intervention to reduce anastomotic leak following right colectomy (EAGLE): pragmatic, batched stepped-wedge, cluster-randomized trial in 64 countries

Background: Anastomotic leak affects 8 per cent of patients after right colectomy with a 10-fold increased risk of postoperative death. The EAGLE study aimed to develop and test whether an international, standardized quality improvement intervention could reduce anastomotic leaks. Methods: The internationally intended protocol, iteratively co-developed by a multistage Delphi process, comprised an online educational module introducing risk stratification, an intraoperative checklist, and harmonized surgical techniques. Clusters (hospital teams) were randomized to one of three arms with varied sequences of intervention/data collection by a derived stepped-wedge batch design (at least 18 hospital teams per batch). Patients were blinded to the study allocation. Low- and middle-income country enrolment was encouraged. The primary outcome (assessed by intention to treat) was anastomotic leak rate, and subgroup analyses by module completion (at least 80 per cent of surgeons, high engagement; less than 50 per cent, low engagement) were preplanned. Results: A total 355 hospital teams registered, with 332 from 64 countries (39.2 per cent low and middle income) included in the final analysis. The online modules were completed by half of the surgeons (2143 of 4411). The primary analysis included 3039 of the 3268 patients recruited (206 patients had no anastomosis and 23 were lost to follow-up), with anastomotic leaks arising before and after the intervention in 10.1 and 9.6 per cent respectively (adjusted OR 0.87, 95 per cent c.i. 0.59 to 1.30; P = 0.498). The proportion of surgeons completing the educational modules was an influence: the leak rate decreased from 12.2 per cent (61 of 500) before intervention to 5.1 per cent (24 of 473) after intervention in high-engagement centres (adjusted OR 0.36, 0.20 to 0.64; P < 0.001), but this was not observed in low-engagement hospitals (8.3 per cent (59 of 714) and 13.8 per cent (61 of 443) respectively; adjusted OR 2.09, 1.31 to 3.31). Conclusion: Completion of globally available digital training by engaged teams can alter anastomotic leak rates. Registration number: NCT04270721 (http://www.clinicaltrials.gov)