Generalizations in the interactions between plants and pollinators

Hasta fechas muy recientes, la mayoría de los estudios teóricos y empíricos sobre la evolución de la relación entre las plantas y sus polinizadores han asumido que estos sistemas están altamente especializados, es decir, cada especie vegetal es visitada por sólo unos cuantos polinizadores relacionados filogenéticamente como fruto de la selección impuesta por ellos. La omnipresencia de especialización se ha derivado de aceptar el principio del polinizador más eficiente, según el cual una planta debe especializarse en el polinizador más eficaz y/o más abundante cuando su disponibilidad es predecible. Muchos estudios han encontrado realmente que los polinizadores ejercen selección fenotípica sobre rasgos reproductivos de las plantas. Sin embargo, igual de evidente es el hecho de que muchas especies vegetales son polinizadas por conjuntos numerosos y taxonómicamente diversos de polinizadores. Estas observaciones sugieren que en realidad los sistemas de polinización son generalistas. La generalización es producida y mantenida por varios factores ecológicos entre los que destacan la variación espacial y la fluctuación temporal de la identidad de los polinizadores más importantes, la similitud en la eficiencia y preferencia por los rasgos florales por parte de polinizadores diferentes, la existencia de factores externos que reducen la capacidad de los polinizadores de afectar al fitness de la planta, y la existencia de selección indirecta.A controversy exists about the importance of generalization versus specialization in pollination systems. Whereas the evolutionary and ecological theory speculates that the plant-pollinator systems should be highly specialized, many evolutionary ecologists now acknowledge that generalization is frequent in natural systems. There is still no consensus about which ecological factors can promote this counter-intuitive and paradoxical result. I propose that generalization in plant-pollination systems can arise by several non-exclusive factors. One kind of factors are related to the ability of pollinators of acting as true selective agents. Despite that many studies have shown that pollinators can provoke phenotypic selection on floral traits, only occasionally it has been shown that this selection actually produces any response to selection. Two main reasons can explain why pollinators cannot induce adaptations in many plants: (1a) a significant spatial and temporal variability in pollinator abundance and identity highly reduces the possibilities of congruent selection on floral traits; (1b) the occurrence of extrinsic factors acting during another stages of the plant reproductive and recruitment processes can also decrease the actual effect that pollinators has on fitness. A second group of factors are those related with the fact that, to specialization occurs, it is necessary that two different pollinators can constitute as completely separated selective agents, by differing in their per-visit efficiencies and/or floral trait preferences. By contrast, similarity in efficiency and preference will constrain specialization even although pollinators act as selective pressures, since plant will have not any criteria to benefit a given pollinator species with respect to the other

Genetic evidences of natural selection

La selección natural es un proceso biológico que constituye uno de los principales motores de cambio evolutivo, y el origen de las adaptaciones fenotípicas. La selección que actúa sobre una determinada población se puede detectar ecológicamente cuantificando a nivel intrapoblacional la relación existente entre el fenotipo de los individuos y su éxito reproductivo diferencial. Sin embargo, detectar la actuación de la selección pretérita es imposible usando una aproximación exclusivamente ecológica. Para afrontar este problema, durante los últimos 40 años se han desarrollado una serie de métodos moleculares que infieren la actuación de la selección. Un primer grupo de pruebas usa como modelo nulo la teoría cuasi neutral de la evolución molecular, y asumen que ha ocurrido selección cuando el resultado difiere significativamente de lo esperable según evolución neutral. Algunos tests, como por ejemplo la D de Tajima, la relación dN/dS , o las pruebas de MK o HKA, pueden determinar incluso el tipo de selección operante. Sin embargo, raramente pueden cuantificar la intensidad de selección. Este inconveniente es exitosamente superado por el análisis de la selección basada en Campos Aleatorios de Poisson (PRF). Un segundo grupo de pruebas usa como método para inferir la acción pretérita de la selección natural la comparación entre la cantidad de diferenciación genética en caracteres cuantitativos (QST) y la cantidad de diferenciación genética neutra (FST). Finalmente, unos de los más recientes y prometedores métodos que se están desarrollando para el estudio de la selección natural está relacionado con el avance tan espectacular que está registrando en la actualidad la genómica. Aún estamos lejos de saber la verdadera utilidad de esta herramienta para el estudio de la selección natural en poblaciones naturales, pero el pronóstico es bastante esperanzador.Natural selection is one of the main factors driving the evolutionary process and the only one leading to adaptations. Selection acting on a population can be detected by quantifying the relationship between individual phenotype and relative fitness. However, detecting the effect of past selection is not possible by only using an ecological approach. To cope with this issue, several molecular evolutionary genetics methods have been developed during the last 40 years. A first group of tests use the quasi neutral theory of molecular evolution as null model, and assume the occurrence of selection when the observed outcome significantly departs from the expectations under neutral evolution. Some tests, such as Tajima’s D, dN/dS ratio, MK test or HKA test, can determine the kind of selection acting on populations, but are unable to quantify its intensity. The analysis of selection based on Poisson Random Fields (PRF) overcomes this caveat. A second group of analyses infer selection by comparing the amount of genetic variation in quantitative traits (QST) against the amount of neutral genetic variation (FST). Lastly, one of the most recent and promising methods to explore natural selection is related with the superb advance in genomics. Although we are still far from fully appreciate the importance of this tool, we believe that the use of the genomics will produce a qualitative enhancement in our understanding of the importance of natural selection in the wild

Preliminary study on the performance of biomorphic silicon carbide as substrate for diesel particulate filters

This paper presents the results of a preliminary experimental study to assess the performance of biomorphic silicon carbide when used for the abatement of soot particles in the exhaust of Diesel engines. Given its optimal thermal and mechanical properties, silicon carbide is one of the most popular substrates in commercial diesel particulate filters. Biomorphic silicon carbide is known for having, besides, a hierarchical porous microstructure and the possibility of tailoring that microstructure through the selection of a suitable wood precursor. An experimental rig was designed and built to be integrated within an engine test bench that allowed to characterizing small lab-scale biomorphic silicon carbide filter samples. A particle counter was used to measure the particles distribution before and after the samples, while a differential pressure sensor was used to measure their pressure drop during the soot loading process. The experimental campaign yielded promising results: for the flow rate conditions that the measuring devices imposed (1 litre per minute; space velocity = 42,000 L/h), the samples showed initial efficiencies above 80%, pressure drops below 20 mbar, and a low increase in the pressure drop with the soot load which allows to reach almost 100% efficiency with an increase in pressure drop lower than 15%, when the soot load is still less than 0.01 g/L. It shows the potential of this material and the interest for advancing in more complex diesel particle filter designs based on the results of this workMinisterio de Economía y Competitividad (España) MAT2013-41233-R DPI2013-46485-C3-3-RFondos FEDER MAT2013-41233-R DPI2013-46485-C3-3-RUniversidad de Sevilla VI Plan Propio I.3B - C.I. 24/05/2017 MAT2016-76526-

Pollinators show flower colour preferences but flowers with similar colours do not attract similar pollinators

Background and aims: colour is one of the main floral traits used by pollinators to locate flowers. Although pollinators show innate colour preferences, the view that the colour of a flower may be considered an important predictor of its main pollinators is highly controversial because flower choice is highly context-dependent, and initial innate preferences may be overridden by subsequent associative learning. Our objective is to establish whether there is a relationship between flower colour and pollinator composition in natural communities. - Methods: we measured the flower reflectance spectrum and pollinator composition in four plant communities (85 plant species represented by 109 populations, and 32 305 plant-pollinator interactions in total). Pollinators were divided into six taxonomic groups: bees, ants, wasps, coleopterans, dipterans and lepidopterans. - Key results: we found consistent associations between pollinator groups and certain colours. These associations matched innate preferences experimentally established for several pollinators and predictions of the pollination syndrome theory. However, flowers with similar colours did not attract similar pollinator assemblages. - Conclusions: the explanation for this paradoxical result is that most flower species are pollination generalists. We conclude that although pollinator colour preferences seem to condition plant-pollinator interactions, the selective force behind these preferences has not been strong enough to mediate the appearance and maintenance of tight colour-based plant-pollinator associations

Suzuki reaction on pyridinium N-(5-bromoheteroar-2-yl)aminides

The reactivity of substituted pyridinium N-(2'-azinyl)aminides in Suzuki-Miyaura cross-coupling reaction is reported. The reaction proceeds in good yield employing Cs2CO3 as base, and producing substitution on the neg. charged moiety. [on SciFinder(R)]We wish to thank the Comisión Interministerial de Ciencia y Tecnología (CICYT-BQU2001-1508) for financial support, and the Ministerio de Educación y Cultura (MEC) for a studentship (M.J.R.)

Pyridinium N-(2´-azinyl)aminides: Regioselective synthesis of N-(2-pyridyl) substituted polyamines

The regioselective alkylation of pyridinium-N-(2¿-pyridyl)aminide with alkyl dihalides under mild conditions, followed by N-N bond reduction of the corresponding bis-salts, allowed an easy preparation of N,N¿-bis(2-pyridyl)diamines. The same methodology has been applied to the synthesis of N,N¿,N¿-tris(2-pyridyl)triamines.The authors wish to thank the Comisión Interministerial de Ciencia y Tecnologı́a (CICYT-2FD97-1248) for financial support, and the Ministerio de Educación y Cultura (MEC) for a studentship (M. J. R.)

An easy preparation of pyridinium N-heteroarylaminides

A synthesis of substituted pyridinium N-heteroarylaminides, e.g., I, is reported. Heteroaryl chlorides underwent nucleophilic substitution with N-aminopyridinium iodide to give the corresponding substituted pyridinium N-heteroarylaminides in good yields. [on SciFinder(R)]Differently substituted pyridinium N-heteroarylaminides have been prepared in one step with good yield from N-aminopyridinium iodide and the corresponding heteroaryl chloride.The authors wish to thank the Ministerio de Ciencia y Tecnología (projects CICYT-2FD97-1248 and BQU2001-1508) for financial support, and the Ministerio de Educación y Cultura for a studenship (M.J.R.)

Regioselective suzuki coupling on pyridinium N-(3,5-dibromoheteroar-2-yl)aminides

A regioselective Suzuki-Miyaura cross-coupling reaction on 3',5'-dibromo pyridinium N-(2'-azinyl)aminides is reported. A series of 3'-aryl(or heteroaryl)-5-bromo-pyridinium N-(2'-pirazinyl)aminides were obtained in good yields. Two isomeric 3',5'-diaryl pyridinium N-(2-azinyl)aminides were also prepared.The authors wish to thank the Comisión Interministerial de Ciencia y Tecnología (CICYT-BQU2001-1508) and the Universidad de Alcalá (UAH GC2005/006) for financial support, and the Ministerio de Educación y Cultura (MEC) for two studentships (M.J.R. and R.C.)

Development and psychometric properties of the stressors in Breast Cancer Scale.

Background: A diagnosis of breast cancer generates psychological stress, due not only to treatment and its side effects but also to the impact on different areas of the patient’s daily life. Although there are instruments for measuring psychological stress in the cancer context, there is currently no tool for assessing stressors specific to breast cancer. Aims: The aim of this study was to develop the Stressors in Breast Cancer Scale (SBCS). Method: A panel of experts evaluated the clarity and relevance of scale items, providing validity evidence based on test content. Psychometric properties of the scale were then analyzed. Results: Validity evidence based on the internal structure of the SBCS was obtained through exploratory factor analysis (EFA) and confirmatory factor analysis (CFA), following a cross-validation strategy. The CFA supported a second-order factor model with five dimensions: physical appearance and sex strains, health and daily difficulties, interpersonal relationship strains, healthcare strains, and worries and concerns about the future. This structure was invariant across two groups distinguished by time from cancer diagnosis (less than 3 and 3 years or more from diagnosis). Reliability, based on McDonald’s omega and Cronbach’s alpha coefficients, ranged from 0.83 to 0.89 for factor scores, and reached 0.95 for total scores. Validity evidence was also provided by correlations with depression, anxiety, perceived stress, and perceived health and quality of life. Discussion: The results support the use of the SBCS for measuring stress as a stimulus in the breast cancer context. Implications for clinical practice and research are discussed.This study was supported by Grupo de investigación consolidado CTS-110, Junta de Andalucía y I Plan Propio y Transferencia de la Universidad de Málaga (ayuda de Publicación en Abierto, C.1

Exergy analysis of solar central receivers

A high-resolution method to analyse the exergy of the SPT external tubular receivers is presented, examining the different heat transfer process involved individually. This sheds light on the role that each irreversibility source plays in the outcome, aiding in the receiver design and the facility location selection. The exergy efficiency is around 32% in the base configuration. Besides the exergy loss in the heliostat field, over 40%, it is found that the biggest exergy destruction cause are the radiation emissions and absorptions in the tube outer surface, around 17%. From the remaining ones, the greatest are the exergy destructed in the HTF and the one escaping to the ambient (over 4% each). Then, the exergy balance for a variety of strategies and ambient conditions is performed: optical properties of the tubes coating, peak and flat aiming strategies, DNI and ambient temperature. The heliostat field exergy loss rate only varies when changing the aiming. However, the emission and absorption losses and the ones in the HTF suffer the greater modifications with all the parameters studied. The impact of the optical properties degradation, 1% descent in the efficiency per 5% degradation, would advise repainting works in order to avoid greater exergy destruction. The surroundings temperature modification impacts considerably the exergy efficiency, showing the suitability of locations with low ambient temperature and a moderate DNI: descends of over 0.35% occur every 5 °C increase of the temperature for a fixed DNI.This research is partially funded by the scholarship "Ayudas para la formación del profesorado universitario"; (FPU-02361) awarded by the Spanish Ministerio de Educación, Cultura y Deporte (MECD), the fellowship"Ayuda a la investigación en energía y medio ambiente" of the Iberdrola España Foundation, the Spanish government under the project RTI2018-096664-B-C21 (MICINN/FEDER, UE) and the call "Programa de apoyo a la realización de proyectos interdisciplinares de I+D para jóvenes investigadores de la Universidad Carlos III de Madrid 2019-2020", under the frame of the Convenio Plurianual Comunidad de Madrid- Universidad Carlos III de Madrid