Trait-mediated indirect effects and complex life-cycles in two European frogs.

Most animals actively avoid predators. If such a reaction reduces competitive ability, for example by reducing food intake, predator presence can lead to trait-mediated indirect effects. Because predator avoidance typically leads to reduced growth rather than reduced survival, its effect on population processes is difficult to assess. This is especially true for organisms with complex life-cycles, where predator avoidance during one stage is expected to lead to traitmediated indirect effects if it has effects reaching into the following life stages. I experimentally investigated the effect of caged (thus non-lethal) dragonfly larvae on the competition between tadpoles of two frog species (Rana lessonae and R. esculenta) and on juvenile frog survival during the subsequent terrestrial stage. In response to caged predators, R. lessonae delayed metamorphosis more than R. esculenta, but they both metamorphosed heavier. These differences suggest the possibility of a competitive disadvantage for R. lessonae in the presence of predators, which could lead to trait-mediated indirect effects. However, the presence of predators did not modify competitive effects and had no measurable consequences on terrestrial survival. Regardless of the presence of predators, competition during the larval stage had large effects on metamorphosis and led to strongly decreased survival in the subsequent terrestrial stage. These results suggest that trait-mediated indirect effects are not important in this system, because the predator reaction of the tadpoles in both species had no measurable effect on the following life stage and, therefore, probably no strong effect on community dynamics

44-jähriger Patient mit kulturnegativer, purulenter Perikarditis

Zusammenfassung: Wir berichten über einen Patienten mit purulenter Perikarditis und drohender Perikardtamponade, verursacht durch Neisseria meningitidis. Bei negativen Kulturen aus Blut und Perikardpunktat, wahrscheinlich bedingt durch die Vorbehandlung mit Antibiotika, konnten wir mittels Breitspektrumpolymerasekettenreaktion aus dem Perikardpunktat und einem Latexagglutinationstest aus Pleurapunktat Meningokokken der SerogruppeC nachweisen. Eine Meningokokkenperikarditis ohne Meningitis ist selten. Diagnostische Methoden auf nicht-kultureller Basis spielen bei Patienten, die bereits mit Antibiotika vorbehandelt sind, eine wichtige Roll

Spondylodiscitis as the first manifestation of Whipple's disease -a removal worker with chronic low back pain

Whipple's disease is a rare systemic infectious disease caused by the actinobacterium Tropheryma whipplei. Spondylodiscitis is an extremely rare manifestation of the infection and has previously been described in only three case reports. We present a 55-year-old man with persistent lumbago and signs of systemic illness, but without any gastrointestinal symptoms or arthralgia. The signal response in the lumbar spine in magnetic resonance tomography, both native and after intravenous gadolinium administration, was compatible with spondylodiscitis at the L4/L5 level. Culture of a specimen obtained by radiographically guided disc puncture and repeated blood cultures remained sterile. Tropheryma whipplei was detected by PCR amplification in material obtained from the disc specimen, from a biopsy of the terminal ileum and from the stool. The histology of duodenum, terminal ileum, colon and disc material was normal and, in particular, showed no PAS-positive inclusions in macrophages. Long-term antibiotic treatment with sulphamethoxazole and trimethoprim was successful, with marked improvement of the low back pain and normalisation of the systemic inflammatory signs. The possibility of Whipple's disease must be suspected in the case of a ‘culture-negative' spondylodiscitis even if there are no gastrointestinal symptoms and no arthralgia presen

Hall Effect in the coma of 67P/Churyumov-Gerasimenko

Magnetohydrodynamics simulations have been carried out in studying the solar wind and cometary plasma interactions for decades. Various plasma boundaries have been simulated and compared well with observations for comet 1P/Halley. The Rosetta mission, which studies comet 67P/Churyumov-Gerasimenko, challenges our understanding of the solar wind and comet interactions. The Rosetta Plasma Consortium observed regions of very weak magnetic field outside the predicted diamagnetic cavity. In this paper, we simulate the inner coma with the Hall magnetohydrodynamics equations and show that the Hall effect is important in the inner coma environment. The magnetic field topology becomes complex and magnetic reconnection occurs on the dayside when the Hall effect is taken into account. The magnetic reconnection on the dayside can generate weak magnetic filed regions outside the global diamagnetic cavity, which may explain the Rosetta Plasma Consortium observations. We conclude that the substantial change in the inner coma environment is due to the fact that the ion inertial length (or gyro radius) is not much smaller than the size of the diamagnetic cavity.Comment: 23 pages, 6 figur

Bottom-up effects of a no-take zone on endangered penguin demographics.

This is the author accepted manuscript. The final version is available from The Royal Society via the DOI in this record.Marine no-take zones can have positive impacts for target species and are increasingly important management tools. However, whether they indirectly benefit higher order predators remains unclear. The endangered African penguin (Spheniscus demersus) depends on commercially exploited forage fish. We examined how chick survival responded to an experimental 3-year fishery closure around Robben Island, South Africa, controlling for variation in prey biomass and fishery catches. Chick survival increased by 18% when the closure was initiated, which alone led to a predicted 27% higher population compared with continued fishing. However, the modelled population continued to decline, probably because of high adult mortality linked to poor prey availability over larger spatial scales. Our results illustrate that small no-take zones can have bottom-up benefits for highly mobile marine predators, but are only one component of holistic, ecosystem-based management regimes.We thank the Earthwatch Institute, Bristol Zoological Society, Leiden Conservation Foundation and National Research Foundation

New European Union fisheries regulations could benefit conservation of marine animals

Peer Reviewe

Origin of molecular oxygen in Comet 67P/Churyumov-Gerasimenko

Molecular oxygen has been detected in the coma of comet 67P/Churyumov-Gerasimenko with abundances in the 1-10% range by the ROSINA-DFMS instrument on board the Rosetta spacecraft. Here we find that the radiolysis of icy grains in low-density environments such as the presolar cloud may induce the production of large amounts of molecular oxygen. We also show that molecular oxygen can be efficiently trapped in clathrates formed in the protosolar nebula, and that its incorporation as crystalline ice is highly implausible because this would imply much larger abundances of Ar and N2 than those observed in the coma. Assuming that radiolysis has been the only O2 production mechanism at work, we conclude that the formation of comet 67P/Churyumov-Gerasimenko is possible in a dense and early protosolar nebula in the framework of two extreme scenarios: (1) agglomeration from pristine amorphous icy grains/particles formed in ISM and (2) agglomeration from clathrates that formed during the disk's cooling. The former scenario is found consistent with the strong correlation between O2 and H2O observed in 67P/C-G's coma while the latter scenario requires that clathrates formed from ISM icy grains that crystallized when entering the protosolar nebula.Comment: The Astrophysical Journal Letters, in pres

Inter-Cohort Competition Drives Density Dependence and Selective Mortality in a Marine Fish

For organisms with complex life cycles, the transition between life stages and between habitats can act as a significant demographic and selective bottleneck. In particular, competition with older and larger conspecifics and heterospecifics may influence the number and characteristics of individuals successfully making the transition. We investigated whether the availability of enemy-free space mediated the interaction between adult goldspot gobies (Gnatholepis thompsoni), a. common tropical reef fish, and juvenile conspecifics that had recently settled from the plankton. We added rocks, which provide refuge from predators, to one-half of each of five entire coral reefs in the Bahamas and measured the survival and growth of recent settlers in relation to adult goby densities. We also evaluated whether mortality was selective with respect to three larval traits (age at settlement, size at settlement, and presettlement growth rate) and measured the influence of refuge availability and adult goby density on selection intensity. Selective mortality was measured by comparing larval traits of newly settled gobies (≤ 5 postsettlement) with those of survivors (2-3 week postsettlement juveniles). We detected a negative relationship between juvenile survival and adult goby density in both low- and high-refuge habitats, though experimental refuge addition reduced the intensity of this density dependence. Juvenile growth also declined with increasing adult goby density, but this effect was similar in both low- and high-refuge habitats. Refuge availability had no consistent effect on selective mortality, but adult goby density was significantly related to the intensity of size-selective mortality: bigger juveniles were favored where adults were abundant, and smaller juveniles were favored where adults were rare. Given the typically large difference in sizes of juveniles and adults, similar stage-structured interactions may be common but underappreciated in many marine species

Is there a future for genome-editing technologies in conservation?

In a recent review, Pimm et al. (2015) highlight emerging technologies in protecting biodiversity. While their list is noteworthy, the authors’ exclusion of innovations in genomic research, with the exception of single-species DNA barcoding methods, was surprising given recent advances in genome-editing technology and its potential application to conservation. Taylor & Gemmell (2016) address that deficiency in a subsequent commentary identifying three avenues where emerging genomic technologies have great potential for increasing our ability to conserve biodiversity. Those areas include the use of next-generation sequencing technologies and methods such as RADseq for monitoring genetic diversity, effective population size, and introgression (Andrews et al., 2016); the use of environmental DNA (eDNA) and metabarcoding approaches to map species occurrence and interaction networks (Evans et al., 2016); and the use of genomic data and gene-editing technology to identify and alter regions of the genome that may impact fitness and limit survival in endangered taxa (Taylor & Gemmell, 2016). Here, we extend that the theme with additional discussion on how genome-editing technologies can benefit the conservation of threatened and endangered species