High temporal variability in the occurrence of consumer-resource interactions in ecological networks

Ecological networks are theoretical abstractions that represent ecological communities. These networks are usually defined as static entities, in which the occurrence of a particular interaction between species is considered fixed despite the intrinsic dynamics of ecological systems. However, empirical analysis of the temporal variation of trophic interactions is constrained by the lack of data with high spatial, temporal, and taxonomic resolution. Here, we evaluate the spatiotemporal variability of multiple consumer-resource interactions of large marine networks. The tropic interactions of all of the analyzed networks had low temporal persistence, which was well described by a common exponential decay in the rank-frequency relationship of consumer-resource interactions. This common pattern of low temporal persistence was evident despite the dissimilarities of environmental conditions among sites. Between-site rank correlations of frequency of occurrence of interactions ranged from 0.59 to 0.73. After removing the interactions with <50% frequency, the between-site correlations decreased to values between 0.60 and 0.28, indicating that low-frequency interactions accounted for the apparent similarities between sites. Our results showed that the communities studied were characterized by few persistent interactions and a large number of transient trophic interactions. We suggest that consumer-resource temporal asynchrony in addition to varying local environmental conditions and opportunistic foraging could be among the mechanisms generating the observed rank-frequency relationship of trophic interactions. Therefore, our results question the analysis of ecological communities as static and persistent natural entities and stress the need for strengthening the analysis of temporal variability in ecological networks and long-term studies.Comment: 21 pages, 3 figure

Whooping Cough Dynamics in Chile (1932-2010): DiseaseTemporal Fluctuations Across a North-South Gradient

Background: The spatial-temporal dynamics of Bordetella pertussis remains as a highly interesting case in infectious disease epidemiology. Despite large-scale vaccination programs in place for over 50 years around the world, frequent outbreaks are still reported in many countries. Methods: Here, we use annual time series of pertussis incidence from the thirteen different regions of Chile (1952–2010) to study the spatial-temporal dynamics of Pertussis. The period 1975–1995 was characterized by a strong 4 year cycle, while the last two decades of the study period (1990–2010) were characterized by disease resurgence without significant periodic patterns. Results: During the first decades, differences in periodic patterns across regions can be explained by the differences in susceptible recruitment. The observed shift in periodicity from the period 1952–1974 to the period 1975–1995 across regions was relatively well predicted by the susceptible recruitment and population size. However, data on vaccination rates was not taken into account in this study. Conclusions: Our findings highlight how demography and population size have interacted with the immunization program in shaping periodicity along a unique latitudinal gradient. Widespread B. pertussis vaccination appears to lead to longer periodic dynamics, which is line with a reduction in B. pertussis transmission, but our findings indicate that regions characterized by both low birth rate and population size decreased in periodicity following immunization efforts

A Simultaneous Test of Synchrony Causal Factors in Muskrat and Mink Fur Returns at Different Scales across Canada

Synchrony among populations has been attributed to three major hypotheses: dispersal, the Moran effect, and trophic-level interactions. Unfortunately, simultaneous testing of these hypotheses demands complete and detailed data, which are scarce for ecological systems.Hudson's Bay Company data on mink and muskrat fur returns in Canada represent an excellent opportunity to test these hypotheses because of the detailed spatial and temporal data from this predator-prey system. Using structural equation modelling, support for each hypothesis was evaluated at two spatial scales: across Canada and dividing the country into three regions longitudinally. Our results showed that at both scales mink synchrony is a major factor determining muskrat synchrony, supporting the hypothesis of trophic-level interactions, but the influence of winter precipitation synchrony is also important in eastern Canada. Moreover, mink synchrony is influenced principally by winter precipitation synchrony at the level of all Canada (Moran effect), but by distance at regional level, which might suggest some influence of dispersal at this level.Our result is one of the few reports of synchrony mediated by trophic-level interactions, highlighting the importance of evaluation of scale effects in population synchrony studies

Impact of global warming at the range margins: Phenotypic plasticity and behavioral thermoregulation will buffer an endemic amphibian

© 2014 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd. When dispersal is not an option to evade warming temperatures, compensation through behavior, plasticity, or evolutionary adaptation is essential to prevent extinction. In this work, we evaluated whether there is physiological plasticity in the thermal performance curve (TPC) of maximum jumping speed in individuals acclimated to current and projected temperatures and whether there is an opportunity for behavioral thermoregulation in the desert landscape where inhabits the northernmost population of the endemic frog Pleurodema thaul. Our results indicate that individuals acclimated to 20°C and 25°C increased the breath of their TPCs by shifting their upper limits with respect to when they were acclimated at 10°C. In addition, even when dispersal is not possible for this population, the landscape is heterogeneous enough to offer opportunities for behavioral thermoregulation. In particular, under current climatic conditions, behavioral thermoregulation is not compulsory as available operative temperatures are encompassed within the population TPC limits. However, for severe projected temperatures under climate change, behavioral thermoregulation will be required in the sunny patches. In overall, our results suggest that this population of Pleurodema thaul will be able to endure the worst projected scenario of climate warming as it has not only the physiological capacities but also the environmental opportunities to regulate its body temperature behaviorally.Link_to_subscribed_fulltex

Experiencia del grupo de estudio de clases insuco en la elaboración de la lección “Regularidades Numéricas en el Triángulo de Pascal”

Este Estudio de Clases tenía por objetivo diseñar una clase en que los alumnos disfrutaran de una actividad lectiva de matemática mientras identifcaban y describían regularidades numéricas. El trabajo culmina con el análisis de las respuestas dadas por cada integrante del grupo respecto a preguntas sobre su experiencia, lo que permite evidenciar que los profesores reconocen un desarrollo de sus conocimientos disciplinarios, en su competencia para trabajar en equipo, en su capacidad crítica y auto crítica, así como también evidencian una valoración positiva respecto a las potencialidades de la implementación de Estudio de Clases. Esta experiencia forma parte de una serie de iniciativas de investigación en torno al Estudio de Clases, entre las cuales se destaca como producto, la publicación de un capítulo en libro NCTM, National Council of Teachers of Mathematic durante el 2014

Spatio-temporal assessment of beech growth in relation to climate extremes in Slovenia – An integrated approach using remote sensing and tree-ring data

Climate change is predicted to affect tree growth due to increased frequency and intensity of extreme events such as ice storms, droughts and heatwaves. Yet, there is still a lot of uncertainty on how trees respond to an increase in frequency of extreme events. Use of both ground-based wood increment (i.e. ring width) and remotely sensed data (i.e. vegetation indices) can be used to scale-up ground measurements, where there is a link between the two, but this has only been demonstrated in a few studies. We used tree-ring data together with crown features derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) to assess the effect of extreme climate events on the growth of beech (Fagus sylvatica L.) in Slovenia. We found evidence that years with climate extremes during the growing season (drought, high temperatures) had a lower ring width index (RWI) but we could not find such evidence for the remotely sensed EVI (Enhanced Vegetation Index). However, when assessing specific events where leaf burning or wilting has been reported (e.g. August 2011) we did see large EVI anomalies. This implies that the impact of drought or heatwave events cannot be captured by EVI anomalies until physical damage on the canopy is caused. This also means that upscaling the effect of climate extremes on RWI by using EVI anomalies is not straightforward. An exception is the 2014 ice storm that caused a large decline in both RWI and EVI. Extreme climatic parameters explained just a small part of the variation in both RWI and EVI by, which could indicate an effect of other climate variables (e.g. late frost) or biotic stressors such as insect outbreaks. Furthermore, we found that RWI was lower in the year after a climate extreme occurred in the late summer. Most likely due to the gradual increase in temperature and more frequent drought we found negative trends in RWI and EVI. EVI maps could indicate where beech is sensitive to climate changes and could be used for planning mitigation interventions. Logical next steps should focus on a tree-based understanding of the short -and long-term effects of climate extremes on tree growth and survival, taking into account differential carbon allocation to the crown (EVI) and to wood-based variables. This research highlights the value of an integrated approach for upscaling tree-based knowledge to the forest level

México: Pasado, presente y futuro Del proteccionismo a la integración / Apertura y crisis de la economía Tomo II

La presente obra no se limita al estudio del surgimiento y evolución de la crisis económica que se inicia a finales de 1994, sino que profundiza en el comportamiento tendencial de las leyes que han caracterizado al sistema económico mexicano en las últimas cinco décadas, con el ánimo de encontrar las causas estructurales que permitan hacer un diagnóstico científico de la compleja situación actual, lo cual crea las condiciones óptimas para elaborar propuestas viables en materia de política económica que permitan lograr el tan ansiado desarrollo económico. Los participantes enfrentaron un reto de enormes proporciones, pues se evalúa una economía que además de tener una seria problemática en cuanto al financiamiento del desarrollo y un cuantioso déficit en la cuenta corriente, enfrenta una crisis estructural del modelo aplicado desde hace más de una década, así como de las políticas económicas adoptadas que no han logrado configurar un esquema de desarrollo que permita aminorar los profundos desequilibrios sectoriales, regionales y distributivos que aquejan a la sociedad mexicana; situación que no puede disociarse de la cada vez mayor internacionalización e integración que se vive en el plano mundial y de la que no escapa nuestro país. Diversos esfuerzos académicos y sociales han demostrado que no es factible sostener que sólo existe una salida a la crisis mexicana. Ésta es una aportación más a la intensa discusión y al debate que existen en la sociedad mexicana

Capitalismo en el nuevo siglo: el actual desorden mundial

El presente libro, resultado de las actividades de la Red de Estudios de la Economía Mundial (redem), reúne un total de ocho textos elaborados por 11 investigadores de Argentina, Cuba, Uruguay y México, los cuales abordan distintos aspectos relevantes de la situación económica mundial de las economías de América Latina y de algu-nos de los países de la región, mediante tres apartados que forman el libro: el primero de ellos titulado El neoli-beralismo y la crisis actual; el segundo apartado, Crisis e integración en América Latina; y el tercero, Dos situacio-nes nacionales: México y Argentina. En los ocho capítulos que forman el presente libro, el lector podrá conocer el análisis de los autores sobre los temas abordados, presentes en el escenario económico global actual, de la región y de algunos países de la mis-ma. La continuidad de la crisis mundial, las característi-cas básicas del neoliberalismo, los efectos de la crisis en América Latina y la situación de la integración regional, así como la reforma energética y la migración en Méxi-co, y las fábricas recuperadas en Argentina, constituyen el abanico de temas, cuyo tratamiento en esta obra esta-mos seguros permitirá a los lectores un acercamiento a la compleja y cambiante realidad que hoy caracteriza al desenvolvimiento económico y social.Desde luego, las tendencias y problemas del desorden económico mundial actual son múltiples, y los abordados en esta obra constituyen sólo algunos de los más relevan-tes, pero sin duda ayudarán al esfuerzo colectivo por dar cuenta, desde una perspectiva crítica, de sus contenidos y posibles trayectorias

Correspondence between the habitat of the threatened pudú (Cervidae) and the national protected-area system of Chile

BACKGROUND: Currently, many species are facing serious conservation problems due to habitat loss. The impact of the potential loss of biodiversity associated with habitat loss is difficult to measure. This is particularly the case with inconspicuous species such as the threatened pudú (Pudu puda), an endemic Cervidae of temperate forests of Chile and Argentina. To evaluate the effectiveness of the Chilean protected-area system in protecting the habitat of the pudú, we measured the congruence between this specie’s potential distribution and the geographical area occupied by the protected areas in central and southern Chile. The measurements of congruency were made using the Maxent modeling method. RESULTS: The potential habitat of the pudú was found to be poorly represented in the system (3–8 %) and even the most suitable areas for the species are not currenly protected. According to these results, the protected area network cannot be considered as a key component of the conservation strategy for this species. CONCLUSIONS: The results presented here also serve as a guide for the reevaluation of current pudú conservation strategies, for the design of new field studies to detect the presence of this species in human-disturbed areas or remaining patches of native forest, and for the implementation of corridors to maximize the success of conservation efforts. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s12898-015-0055-7) contains supplementary material, which is available to authorized users