Competition level determines compensatory growth abilities

In many animal taxa, size-selective predation favors fast growth early in life. However, same-aged juveniles can diverge in size due to differences in genotype, environmental conditions, and parental effects and thus may vary in competitive ability. Under food scarcity, competitively inferior juveniles may suffer suppressed growth, whereas under benign conditions, small juveniles may exhibit growth compensation and perform as well as large ones. However, studies testing this while controlling for parental effects are lacking. Here, we hand-raised cichlids, Simochromis pleurospilus, from a wide range of egg sizes and manipulated their size by differential feeding. Afterward, high- and low-ration siblings were kept in groups assigned to either a high- or low-competition environment. We investigated how the degree of competition affected aggressiveness and growth of juveniles with different feeding histories. As predicted, when competition was high, high-ration offspring grew fastest. Interestingly, when competition was weak, low-ration juveniles grew at a similar rate as high-ration ones and many were able to catch up in size. High-ration fish were more aggressive than low-ration ones, and this effect was strongest under high competition. Additionally, in the high-competition environment, received aggression was negatively related to growth, and inflicted aggression correlated positively with the growth of the aggressor. These relationships were absent under low competition. Our findings suggest that the abilities to compensate for early growth depression depend on the prevalent level of competition. Aggression is likely used to monopolize food by juvenile S. pleurospilus; however, when competition is strong, aggression cannot compensate for a size disadvantag

Characterization of defects in a martensitic CuAlNi shape-memory alloy

A water-quenched martensitic CuAlNi shape-memory alloy was investigated by a combination of coincidence Doppler broadening and positron-lifetime spectroscopy, supported by positron-lifetime calculations. We find a high defect concentration in the as-quenched samples. The positron-lifetime calculations suggest that the defects are not only single vacancies but also vacancies associated with dislocations and stacking faults. Annealing in the martensitic phase has no significant influence on the vacancy concentration but results in a different chemical environment around the vacancies. After aging in the austenitic phase the vacancy concentration decreases significantl

The 'rotiferologist' effect and other global correlates of species richness in monogonont rotifers

Global biodiversity patterns are often driven by diff erent environmental variables at diff erent scales. However, it is still controversial whether there are general trends, whether similar processes are responsible for similar patterns, and/or whether confounding eff ects such as sampling bias can produce misleading results. Our aim is twofold: 1) assessing the global correlates of diversity in a group of microscopic animals little analysed so far, and 2) inferring the infl uence of sampling intensity on biodiversity analyses. As a case study, we choose rotifers, because of their high potential for dispersal across the globe. We assembled and analysed a new worldwide dataset of records of monogonont rotifers, a group of microscopic aquatic animals, from 1960 to 1992. Using spatially explicit models, we assessed whether the diversity patterns conformed to those commonly obtained for larger organisms, and whether they still held true after controlling for sampling intensity, variations in area, and spatial structure in the data. Our results are in part analogous to those commonly obtained for macroorganisms (habitat heterogeneity and precipitation emerge as the main global correlates), but show some divergence (potential absence of a latitudinal gradient and of a large-scale correlation with human population). Moreover, the eff ect of sampling eff ort is remarkable, accounting for 50% of the variability; this strong eff ect may mask other patterns such as latitudinal gradients. Our study points out that sampling bias should be carefully considered when drawing conclusions from large-scale analyses, and calls for further faunistic work on microorganisms in all regions of the world to better understand the generality of the processes driving global patterns in biodiversity

Energie- en klimaatmonitor agrosectoren 2011

Onderzoek van Agenschap NL en WUR-LEI in opdracht van het ministerie van Economische Zaken, Landbouw en Innovatie (EL&I). Uit de monitor blijkt dat de Nederandse land- en tuinbouwbedrijven meer elektriciteit produceren dan ze zelf verbruiken. De totale bijdrage van deze sectoren aan de in Nederland gebruikte duurzame energie is 44 procent. Ruim de helft van het energieverbruik van de land- en tuinbouwbedrijven zelf (uitgezonderd de glastuinbouw) is afkomstig uit hernieuwbare bronnen

Towards a list of available names in zoology, partim Phylum Rotifera

Many, mostly older, names of animal species are nomenclaturally problematic, either because their orthography is unstable, or they cannot be linked reliably to a taxonomic identity, due to the lack of recognisable descriptions and/or types. Yet, they represent available (sensu International Code of Zoological Nomenclature) names and must be taken into account in zoological works. This situation, with available senior, yet dubious names confounding nomenclature, is undesirable. It creates uncertainties at a time when molecular approaches are revolutionizing our concepts of species diversity, and fails us when the current extinction crisis calls for efficient, accurate, and constructive approaches to document, monitor, and conserve biodiversity. The International Code of Zoological Nomenclature (The Code) provides a means to address this issue by restricting availability, application and orthography of names to those included in the List of Available Names in Zoology (LAN). The Code (Art. 79) allows an international body of zoologists in consultation with the Commission to propose a candidate part of the LAN for a major taxonomic field. We explore this possibility for 3570 species-group names of Phylum Rotifera (of which 665 are problematic), by presenting such a candidate Rotifera part of the LAN. The web site of the International Commission on Zoological Nomenclature (http://www.iczn.org) will hold both the candidate list and a forum to facilitate consultation on the candidate list, while the list itself also can already be freely downloaded from three other Internet sites: http://fada.biodiversity. be, http://rotifer.ansp.org/LAN, and www.hausdernatur.at/rotifera. We give here an overview of the general approach and procedures applied in preparation of the candidate list, and anticipate that our effort will promote the process as well as result in a standard list of names for use in taxonomy, the Global Names Architecture and other biodiversity information initiatives

Flickering AGN can explain the strong circumgalactic O VI observed by COS-Halos

Proximity zone fossils (PZFs) are ionization signatures around recently active galactic nuclei (AGNs) where metal species in the circumgalactic medium remain overionized after the AGNs have shut off due to their long recombination time scales. We explore cosmological zoom hydrodynamic simulations, using the EAGLE (Evolution and Assembly of GaLaxies and their Environments) model paired with a non-equilibrium ionization and cooling module including time-variable AGN radiation to model PZFs around star-forming disc galaxies in the z ∼ 0.2 Universe. Previous simulations typically underestimated the O VI content of galactic haloes, but we show that plausible PZF models increase O VI column densities by 2 − 3 × to achieve the levels observed around COS-Halos star-forming galaxies out to 150 kpc. Models with AGN bolometric luminosities 1043.6erg s−1, duty cycle fractions 10 per cent, and AGN lifetimes 106 yr are the most promising, because their supermassive black holes grow at the cosmologically expected rate and they mostly appear as inactive AGN, consistent with COS-Halos. The central requirement is that the typical star-forming galaxy hosted an active AGN within a time-scale comparable to the recombination time of a high metal ion, which for circumgalactic O VI is ≈107 yr. H I, by contrast, returns to equilibrium much more rapidly due to its low neutral fraction and does not show a significant PZF effect. O VI absorption features originating from PZFs appear narrow, indicating photoionization, and are often well aligned with lower metal ion species. PZFs are highly likely to affect the physical interpretation of circumgalactic high ionization metal lines if, as expected, normal galaxies host flickering AGN