Are there so many congeneric species of chironomid larvae in a small stream?

The co-occurrence of larvae of congeneric chironomid species is common in natural stream assemblages, and raises the problem of finding mechanisms to explain the co-existence of species with similar ecological requirements. In this contribution, we explored the co-occurrence of chironomid larvae belonging to congeneric species within four genera of chironomids: Cricotopus, Eukiefferiella, Orthocladius and Rheocricotopus (with 2, 7, 2 and 4 species, respectively) in the headwaters of a small Mediterranean calcareous stream. Due to the intrinsic, natural spatial and temporal variability in these habitats, we studied three different sites at two different seasons within the annual hydrological cycle (spring vs summer samples), and each microhabitat unit was surveyed with an effort proportional to its cover at the sampling site. The Outlying Median Index method was used to distinguish the niches of the different chironomid species in relation to the hydraulic features and substrates within each site. Our results showed that hydraulic features helped to improve discrimination between the niches of five congeneric species of Eukiefferiella, and the same occurred within the species belonging to Cricotopus and Orthocladius, although niche overlap was high in general. One Rheocricotopus species was associated to algal substrate. Schoener's co-occurrence at the microhabitat scale was low among the congeneric species found in our study, suggesting exclusion mechanisms. Flow regime, substrate type and shifts in environmental conditions may favor the settlement of some species to the detriment of other congeneric ones, but other mechanisms such as lottery competition, diffusion competition or predation should be considered in further studies

Análisis de estados financieros y su influencia en la toma de decisiones: una revisión de la literatura científica

El mundo es un lugar de constantes cambios, de la misma manera los mercados y por ende las empresas que operan en ellos se ven afectos por estos. Es por ello por lo que es vital para todas las organizaciones hoy en día tener un adecuado manejo para cuidar sus finanzas. La gran mayoría de empresas frecuentemente se ve en necesidad de tomar medidas correctivas o apostar por un proyecto nuevo, pero nada de esto sería posible si no se conoce con exactitud la situación en la cual se encuentra la empresa, para a través de ello reconocer las necesidades y limitaciones con las que cuenta

Análisis demográfico de bancos de huevos diapáusicos de rotíferos

Los huevos diapáusicos de rotíferos se han reconocido como una etapa fundamental del ciclo vital de los rotíferos que habitan ambientes temporalmente variables ya que permiten la supervivencia de las poblaciones durante los periodos de condiciones adversas. No obstante, el estudio de los bancos de huevos diapáusicos de rotíferos en ambientes naturales ha recibido mucha menos atención que el estudio de sus poblaciones activas. La mayor parte de la información sobre etapas de resistencia en el zooplancton proviene de otros grupos (cladóceros y copépodos). El objetivo de esta tesis consiste en caracterizar demográficamente los bancos de huevos diapáusicos del complejo de especies del rotífero Brachionus plicatilis en un conjunto de 15 charcas y lagunas en la región oriental de la Península Ibérica, así como inferir los procesos que determinan las propiedades de los bancos de huevos en relación con las características del hábitat en el contexto general de la teoría de evolución de rasgos vitales. Los resultados obtenidos muestran que los bancos de huevos diapáusicos del complejo B. plicatilis pueden ser muy densos (2-200 huevos cm-2). La variación en profundidad de los valores de abundancia de huevos diapáusicos indica una alta variación interanual en la producción de huevos diapáusicos. La gran abundancia de huevos deteriorados en el sedimento (60-95%) indica una elevada mortalidad y sugiere que los procesos de deterioro son importantes. La huevos viables típicamente se concentran en las capas más superficiales del sedimento y su proporción disminuye con la profundidad, lo que sugiere un proceso de envejecimiento. La datación de los sedimentos indicó que los bancos estudiados son relativamente jóvenes, con una mediana de edad de entre 3 y 30 años y una edad máxima de 60-80 años. En esta tesis se ha propuesto un modelo dinámico donde se contemplan los distintos procesos que afectan a los bancos de huevos

Are there so many congeneric species of chironomid larvae in a small stream?

The co-occurrence of larvae of congeneric chironomid species is common in natural stream assemblages, and raises the problem of finding mechanisms to explain the co-existence of species with similar ecological requirements. In this contribution, we explored the co-occurrence of chironomid larvae belonging to congeneric species within four genera of chironomids: Cricotopus, Eukiefferiella, Orthocladius and Rheocricotopus (with 2, 7, 2 and 4 species, respectively) in the headwaters of a small Mediterranean calcareous stream. Due to the intrinsic, natural spatial and temporal variability in these habitats, we studied three different sites at two different seasons within the annual hydrological cycle (spring vs summer samples), and each microhabitat unit was surveyed with an effort proportional to its cover at the sampling site. The Outlying Median Index method was used to distinguish the niches of the different chironomid species in relation to the hydraulic features and substrates within each site. Our results showed that hydraulic features helped to improve discrimination between the niches of five congeneric species of Eukiefferiella, and the same occurred within the species belonging to Cricotopus and Orthocladius, although niche overlap was high in general. One Rheocricotopus species was associated to algal substrate.  Schoener’s co-occurrence at the microhabitat scale was low among the congeneric species found in our study, suggesting exclusion mechanisms. Flow regime, substrate type and shifts in environmental conditions may favor the settlement of some species to the detriment of other congeneric ones, but other mechanisms such as lottery competition, diffusion competition or predation should be considered in further studies

Parasite-host relationships of water mites (Acari: Hydrachnidia) and black flies (Diptera: Simuliidae) in southeastern Spain

Abstract Background: Documentation on water mites in Spain is scarce, as is information on the parasite-host relationship between certain water mite species and representatives of the dipteran family Simuliidae. The discomfort caused to humans and animals by black fies seems to be increasing in recent years. In this context, an investigation of parasitic water mites is of great importance, not only from the point of view of biodiversity, but also in terms of their potential to control black fy populations. Methods: Rivers across a wide region of eastern Spain were sampled to determine the specifc richness of simuliid dipterans and to investigate their possible parasites, such as water mites, mermithid nematodes and microsporidia (fungal microbes). Data on environmental variables, abundance, prevalence and intensity of parasitism on the collected specimens were analyzed. Results: In 10 streams, 15,396 simuliid pupae were collected and checked for the presence of water mite larvae; 426 pupae in seven streams were found to be associated with water mite larvae. Of the 21 simuliid species identifed based on morphological characters, eight were found to be associated with water mite larvae. Water mite infection was not equally distributed among black fy species. Also, the prevalence of parasitism was low and difered among simuliid species, ranging from one to 13 water mites per black fy pupa. Variation at the intra- and interspecifc levels was detected in terms of the number of water mites inside the black fy cocoons. Free-living deutonymphal and adult water mites representing 15 diferent species of six genera and fve families were morphologically identifed. The taxonomic identity of the parasitic mite larvae is unclear at present. Morphologically, they ft descriptions of larval Sperchon (Hispidosperchon) algeriensis Lundblad, 1942, but the possibility cannot be excluded that they represent Sperchon algeriensis, the most abundant species at the adult stage in this study and unknown at the larval stage, or even another species of the genus. A molecular analysis produced for the frst time cytochrome oxidase I gene sequences for S. algeriensis. Conclusions: Our results contribute to current knowledge on Spanish Hydrachnidia and their relationships with simuliids as hosts. However, further research is needed to evaluate the diversity, distribution, bioecology and prevalence of this parasitism

Gene expression in diapausing rotifer eggs in response to divergent environmental predictability regimes

In unpredictable environments in which reliable cues for predicting environmental variation are lacking, a diversifying bet-hedging strategy for diapause exit is expected to evolve, whereby only a portion of diapausing forms will resume development at the first occurrence of suitable conditions. This study focused on diapause termination in the rotifer Brachionus plicatilis s.s., addressing the transcriptional profile of diapausing eggs from environments differing in the level of predictability and the relationship of such profiles with hatching patterns. RNA-Seq analyses revealed significant differences in gene expression between diapausing eggs produced in the laboratory under combinations of two contrasting selective regimes of environmental fluctuation (predictable vs unpredictable) and two different diapause conditions (passing or not passing through forced diapause). The results showed that the selective regime was more important than the diapause condition in driving differences in the transcriptome profile. Most of the differentially expressed genes were upregulated in the predictable regime and mostly associated with molecular functions involved in embryo morphological development and hatching readiness. This was in concordance with observations of earlier, higher, and more synchronous hatching in diapausing eggs produced under the predictable regime

Ecological genomics of adaptation to unpredictability in experimental rotifer populations

Elucidating the genetic basis of phenotypic variation in response to different environments is key to understanding how populations evolve. Facultatively sexual rotifers can develop adaptive responses to fluctuating environments. In a previous evolution experiment, diapause-related traits changed rapidly in response to two selective regimes (predictable vs unpredictable) in laboratory populations of the rotifer Brachionus plicatilis. Here, we investigate the genomic basis of adaptation to environmental unpredictability in these experimental populations. We identified and genotyped genome-wide polymorphisms in 169 clones from both selective regimes after seven cycles of selection using genotyping by sequencing (GBS). Additionally, we used GBS data from the 270 field clones from which the laboratory populations were established. This GBS dataset was used to identify candidate SNPs under selection. A total of 76 SNPs showed divergent selection, three of which are candidates for being under selection in the particular unpredictable fluctuation pattern studied. Most of the remaining SNPs showed strong signals of adaptation to laboratory conditions. Furthermore, a genotype-phenotype association approach revealed five SNPs associated with two key life-history traits in the adaptation to unpredictability. Our results contribute to elucidating the genomic basis for adaptation to unpredictable environments and lay the groundwork for future evolution studies in rotifers

Genomic signatures of local adaptation to the degree of environmental predictability in rotifers

Environmental fuctuations are ubiquitous and thus essential for the study of adaptation. Despitethis, genome evolution in response to environmental fuctuations —and more specifcally to thedegree of environmental predictability– is still unknown. Saline lakes in the Mediterranean regionare remarkably diverse in their ecological conditions, which can lead to divergent local adaptationpatterns in the inhabiting aquatic organisms. The facultatively sexual rotifer Brachionus plicatilis showsdiverging local adaptation in its life-history traits in relation to estimated environmental predictabilityin its habitats. Here, we used an integrative approach —combining environmental, phenotypic andgenomic data for the same populations– to understand the genomic basis of this diverging adaptation.Firstly, a novel draft genome for B. plicatilis was assembled. Then, genome-wide polymorphisms werestudied using genotyping by sequencing on 270 clones from nine populations in eastern Spain. As aresult, 4,543 high-quality SNPs were identifed and genotyped. More than 90 SNPs were found tobe putatively under selection with signatures of diversifying and balancing selection. Over 140 SNPswere correlated with environmental or phenotypic variables revealing signatures of local adaptation,including environmental predictability. Putative functions were associated to most of these SNPs, sincethey were located within annotated genes. Our results reveal associations between genomic variationand the degree of environmental predictability, providing genomic evidence of adaptation to localconditions in natural rotifer populations

A comparative analysis of printing techniques by using an active concentric ring electrode for bioelectrical recording

Purpose This paper aims to present a comparison between three types of manufacturing techniques, namely, screen-printed, inkjet and gravure, using different types of inks, for the implementation of concentric ring electrodes which permit estimation of Laplacian potential on the body surface. Design/methodology/approach Flexible concentric ring electrodes not only present lower skin electrode contact impedance and lower baseline wander than rigid electrodes but are also less sensitive to interference and motion artefacts. The above three techniques allow printing of conductive inks on flexible substrates, and with this work, the authors aim to study which is the best technique and ink to obtain the best electrode response. Findings From the results obtained regarding ink thickness, resistivity, electrode resistance and other performance parameters derived from electrocardiographic signal recording tests, it can be said that concentric electrodes using the screen-printing and inkjet techniques are suitable for non-invasive bioelectric signal acquisition. Originality/value The development of new types of inks and substrates for the electronics industry and the adaptation of new manufacturing techniques allow for an improvement in the development of electrodes and sensors.This work was financially supported by the Spanish Government and European FEDER funds (MAT2012-38429-C04-04).García Breijo, E.; Prats Boluda, G.; Lidon-Roger, JV.; Ye Lin, Y.; Garcia Casado, FJ. (2015). A comparative analysis of printing techniques by using an active concentric ring electrode for bioelectrical recording. Microelectronics International. 32(2):103-107. https://doi.org/10.1108/MI-03-2015-0021S103107322Besio, W., Aakula, R., Koka, K., & Dai, W. (2006). Development of a Tri-polar Concentric Ring Electrode for Acquiring Accurate Laplacian Body Surface Potentials. Annals of Biomedical Engineering, 34(3), 426-435. doi:10.1007/s10439-005-9054-8Besio, W., & Chen, T. (2007). Tripolar Laplacian electrocardiogram and moment of activation isochronal mapping. Physiological Measurement, 28(5), 515-529. doi:10.1088/0967-3334/28/5/006He, B., & Cohen, R. J. (1992). Body surface Laplacian mapping of cardiac electrical activity. The American Journal of Cardiology, 70(20), 1617-1620. doi:10.1016/0002-9149(92)90471-aLu, C.C. and Tarjan, P.P. (2002), “An ultra-high common-mode rejection ratio (CMRR) AC instrumentation amplifier for laplacian electrocardiographic measurement”,Biomedical Instrumentation and Technology, Vol. 33 No. 1, pp. 76-83.Prats-Boluda, G. , Ye-Lin, Y. , Garcia-Breijo, E. , Ibanez, J. and Garcia-Casado, J. (2012), “Active flexible concentric ring electrode for non-invasive surface bioelectrical recordings”,Measurement Science & Technology, Vol. 23 No. 12

Characterization of Screen-Printed Organic Electrochemical Transistors to Detect Cations of Different Sizes

[EN] A novel screen-printing fabrication method was used to prepare organic electrochemical transistors (OECTs) based on poly(3,4-ethylenedioxythiophene) doped with polysterene sulfonate (PEDOT:PSS). Initially, three types of these screen-printed OECTs with a different channel and gate areas ratio were compared in terms of output characteristics, transfer characteristics, and current modulation in a phosphate buffered saline (PBS) solution. Results confirm that transistors with a gate electrode larger than the channel exhibit higher modulation. OECTs with this geometry were therefore chosen to investigate their ion-sensitive properties in aqueous solutions of cations of different sizes (sodium and rhodamine B). The effect of the gate electrode was additionally studied by comparing these all-PEDOT:PSS transistors with OECTs with the same geometry but with a non-polarizable metal gate (Ag). The operation of the all-PEDOT:PSS OECTs yields a response that is not dependent on a Na+ or rhodamine concentration. The weak modulation of these transistors can be explained assuming that PEDOT:PSS behaves like a supercapacitor. In contrast, the operation of Ag-Gate OECTs yields a response that is dependent on ion concentration due to the redox reaction taking place at the gate electrode with Cl− counter-ions. This indicates that, for cation detection, the response is maximized in OECTs with non-polarizable gate electrodes.Financial support from FEDER and Spanish Government funds (MAT2015-64139-C4-3-R (MINECO/FEDER)) and GVA funds (AICO/2015/103) are gratefully acknowledged.Contat-Rodrigo, L.; Pérez Fuster, C.; Lidon-Roger, JV.; Bonfiglio, A.; Garcia-Breijo, E. (2016). Characterization of Screen-Printed Organic Electrochemical Transistors to Detect Cations of Different Sizes. Sensors. 16(10). https://doi.org/10.3390/s16101599S15991610Shirakawa, H., Louis, E. J., MacDiarmid, A. 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