Varying patterns on varying scales: A metacommunity analysis of nematodes in European lakes

Dümmer B, Ristau K, Traunspurger W. Varying patterns on varying scales: A metacommunity analysis of nematodes in European lakes. PLOS One. 2016;11(3): e0151866.Ecological community patterns are often extremely complex and the factors with the greatest influence on community structure have yet to be identified. In this study we used the elements of metacommunity structure (EMS) framework to characterize the metacommunities of freshwater nematodes in 16 European lakes at four geographical scales (radius ranging from 80 m to 360 km). The site characteristics associated with site scores indicative of the structuring gradient were identified using Spearman rank correlations. The metacommunities of the 174 nematode species included in this analysis mostly had a coherent pattern. The degree of turnover increased with increasing scale. Ordination scores correlated with geographical variables on the larger scales and with the trophic state index on a regional scale. The association of the structuring gradient with spatial variables and the scale-dependent increase in turnover showed that nematode dispersal was limited. The different metacommunity patterns identified at the increasing geographical scales suggested different, scale-related mechanisms of species distribution, with species sorting dominating on smaller and mass effects on larger geographical scales

Fertilization benefits the facultative parasitic plant Rhamphicarpa fistulosa while gains by the infected host Oryza sativa are marginalized

• Background and Aims. Rhamphicarpa fistulosa (Hochst.) Benth. is an annual facultative parasitic plant adapted to hydromorphic soils. In sub-Saharan Africa it causes high crop losses as a weed in rainfed lowland rice (Oryza sativa L.). Fertilisers are often proposed as control measure against hemiparasitic weeds but understanding of nutrient effects on R. fistulosa is currently still elusive. • Methods. In two greenhouse pot experiments, conducted in 2016 in the Netherlands and in 2019 in the UK, host plants (O. sativa, cv IR64) and parasitic plants (R. fistulosa) were grown alone or combined, and subjected to different nutrient availability levels. Biomass measurements were used to assess if and how nutrient availability effects are expressed in the host and parasite. • Key Results. Compared to parasite-free host plants, the biomass of parasite-infested plants was severely reduced and nutrient effects on host plant biomass were less pronounced. Inversely, increased nutrient availability did not have an effect on parasitic plants when grown alone, but when grown with a host the parasitic plant biomass proportionally increased. Grown together, the combined biomass of host plant and parasite was substantially lower than that of the host plant grown alone. The ratio in biomass between host plant and parasite was unaffected by nutrient availability. • Conclusions. Fertilization benefits to rice plants are severely reduced but not completely nullified by R. fistulosa infection. The parasite's production and reproduction benefits accrued from increased nutrient availability are restricted to conditions in presence of a host plant. Host presence and nutrient effects are thus observed to be synergetic; R. fistulosa plants parasitizing a suitable host respond strongly to increasing levels of nutrients. This is associated with an increased root biomass of the parasitic plant itself but more likely resulting from exploitation of the nutrient uptake capacity of the host plant it parasitizes on

Los desafíos de escenificar el “alma nacional”. Chile en la Exposición Iberoamericana de Sevilla (1929).

This article examines Chilean national imaginaries during the 1920s and their graphic and material representation. It does so through a concrete case: the preparations and staging of Chile's pavilion in the Ibero-American Exposition of 1929 in Seville. The study begins by explaining the influence of culturalist nationalism on Chilean imaginaries and the need to represent the "national soul" in the exposition. It then analyzes how these ideas were physically and graphically represented in the country's exhibit. Special attention is paid to the representational challenges and the negotiations between different participants concerning the content of the exhibit

"Cuestión Judía" en España durante el reino visigodo: acusación de conjura contra el monarca bajo el reinado de Egica (694)

This piece of research studies one particular episode in the history of the Jews in the Visigoth kingdom of the VII century: the accusation of their conspiracy against King Egica in 694. The main objective is to determine whether the punishment imposed on the supposed conspirators corresponded to a genuine reaction against a perceived menace or if this was only an interested move by the monarch. In order to do this we are going to analyse the Councilliar Documents of the period along with the reconstruction of the conditions under which the Visigoth kings governed, based on the available bibliography.La presente investigación aborda el tema de la "cuestión judía" en el Reino Visigodo durante el siglo VII. Particularmente, la acusación de conspirar contra el Rey Egica que se le imputó a este grupo en 694. El ensayo tiene como objetivo determinar si el castigo impuesto a los supuestos conspiradores correspondió a una reacción genuina ante la amenaza, o bien se trató de una maniobra interesada por parte del monarca. Para ello, se desarrolla un análisis de los documentos conciliares del período, además de reconstruir el período y las condiciones bajo las cuales gobernaron los reyes visigodos a partir de la bibliografía existente

De Rooms-Katholieke begraafplaats te Sneek 1892-2017

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Entre el norte y el sur: norteaméricanización en México y Chile en el siglo XX temprano. Una visión comparativa

Las influencias culturales estadounidenses en Chile y México tomaron forma durante el primer tercio del siglo XX. Pese a las diferencias geográficas e históricas entre ambos países, es posible ver importantes similitudes en sus procesos de “norteamericanización”. Las facilidades para viajar y la circulación de símbolos culturales a través de los medios de masas, hicieron que la cercanía geográfica no fuera condición previa para el encuentro con la cultura estadounidense. Por un lado, se generó en los centros urbanos de ambos países un escenario parecido. Por otro lado, la influencia estadounidense fue vista por muchos chilenos y mexicanos como una amenaza a la que había que frenar y oponer resistencia. Llama la atención que en ambos casos se recurriera a la promoción de la cultura propia como defensa ante la influencia foránea.

Nematode colonisation of artificial water-filled tree holes

Ptatscheck C, Dümmer B, Traunspurger W. Nematode colonisation of artificial water-filled tree holes. Nematology. 2015;17(8):911-921