549 research outputs found
Pesticide exposure enhances dominance patterns in a zooplankton community
No full textExposure to pesticides can profoundly alter community dynamics. It is expected that dominance patterns will be enhanced or reduced depending on whether the dominant species is less or more sensitive to the pesticide than the subdominant species. Community dynamics are, however, also determined by processes linked to population growth as well as competition at carrying capacity. Here, we used a mesocosm experiment to quantify the effect of chlorpyrifos exposure on the population dynamics of four cladoceran species (Daphnia magna, Daphnia pulicaria, Daphnia galeata and Scapholeberis mucronata) in mixed cultures, testing for direct effects of chlorpyrifos and indirect effects mediated by interactions with other species on the timing of population growth and dominance at carrying capacity. We also quantified whether the pesticide-induced changes in community dynamics affected top-down control of phytoplankton. By adding a treatment in which we used different genotype combinations of each species, we also tested to what extent genetic composition affects community responses to pesticide exposure. Immobilization tests showed that D. magna is the least sensitive to chlorpyrifos of the tested species. Chlorpyrifos exposure first leads to a reduction in the abundance of D. galeata to the benefit of D. pulicaria, and subsequently to a reduction in densities of D. pulicaria to the benefit of D. magna. This resulted in D. magna being more dominant in the pesticide than in the control treatment by the end of the experiment. There was no effect of genotypic differences on community patterns, and top-down control of phytoplankton was high in all treatments. Our results suggest that in this community dominance patterns are enhanced in line with the observed among-species differences in sensitivity to the pesticide. Our results also show that the development of the community in pesticide treatment is a complex interaction between direct and indirect effects of the pesticide.FWO, Grant/Award Numbers: 11E3222N, G0B9818; KU Leuven, Grant/Award Number: C16/2017/002
This study was financially supported by FWO project G0B9818 and KU Leuven Research Fund project C16/2017/002. Rafaela A. Almeida acknowledges a FWO PhD SB fellowship (application 1S04618N) and Maxime Fajgenblat a FWO PhD FR fellowship (application 11E3222N). We thank Edwin van den Berg and Julie Tytgat for their valuable help with the practical work
Dispersal evolution alters evolution-mediated priority effects in a metacommunity
No full textBiologists have long sought to predict the distribution of species across landscapes to understand biodiversity patterns and dynamics. These efforts usually integrate ecological niche and dispersal dynamics, but evolution can also mediate these ecological dynamics. Species that disperse well and arrive early might adapt to local conditions, which creates an evolution-mediated priority effect that alters biodiversity patterns. Yet, dispersal is also a trait that can evolve and affect evolution-mediated priority effects. We developed an individual-based model where populations of competing species can adapt not only to local environments but also to different dispersal probabilities. We found that lower regional species diversity selects for populations with higher dispersal probabilities and stronger evolution-mediated priority effects. When all species evolved dispersal, they monopolized fewer patches and did so at the same rates. When only one of the species evolved dispersal, it evolved lower dispersal than highly dispersive species and monopolized habitats once freed from maladaptive gene flow. Overall, we demonstrate that dispersal evolution can shape evolution-mediated priority effects when provided with a greater ecological opportunity in species-poor communities. Dispersal- and evolution-mediated priority effects probably play greater roles in species-poor regions like the upper latitudes, isolated islands and in changing environments.This article is part of the theme issue 'Diversity-dependence of dispersal: interspecific interactions determine spatial dynamics'.Funding
M.F. acknowledges a FWO PhD FR fellowship (application 11E3222N). L.D.M. was supported by KU Leuven Research Fund project C16/23/003, FWO project G0A3M24 and the PONDERFUL project (grant no. H2020-LC-CLA-2019-2, funded by the European Union). M.C.U. was supported by NASA awards nos. 80NSSC22K0883 and 80NSSC19K0476, the Arden Chair in Ecology and Evolutionary Biology and a Leverhulme visiting professorship
Acknowledgements.
We thank Emanuel Fronhofer and Dries Bonte for inviting us to participate in this special issue, as well as the anonymous reviewers who improved our manuscript
Evaluating the direct effect of vaccination and non-pharmaceutical interventions during the COVID-19 pandemic in Europe
No full textBackgroundAcross Europe, countries have responded to the COVID-19 pandemic with a combination of non-pharmaceutical interventions and vaccination. Evaluating the effectiveness of such interventions is of particular relevance to policy-makers.MethodsWe leverage almost three years of available data across 38 European countries to evaluate the effectiveness of governmental responses in controlling the pandemic. We developed a Bayesian hierarchical model that flexibly relates daily COVID-19 incidence to past levels of vaccination and non-pharmaceutical interventions as summarised in the Stringency Index. Specifically, we use a distributed lag approach to temporally weight past intervention values, a tensor-product smooth to capture non-linearities and interactions between both types of interventions, and a hierarchical approach to parsimoniously address heterogeneity across countries.ResultsWe identify a pronounced negative association between daily incidence and the strength of non-pharmaceutical interventions, along with substantial heterogeneity in effectiveness among European countries. Similarly, we observe a strong but more consistent negative association with vaccination levels. Our results show that non-linear interactions shape the effectiveness of interventions, with non-pharmaceutical interventions becoming less effective under high vaccination levels. Finally, our results indicate that the effects of interventions on daily incidence are most pronounced at a lag of 14 days after being in place.ConclusionsOur Bayesian hierarchical modelling approach reveals clear negative and lagged effects of non-pharmaceutical interventions and vaccination on confirmed COVID-19 cases across European countries. As soon as COVID-19 hit Europe in early 2020, non-pharmaceutical interventions such as movement restrictions and social distancing were employed to contain the pandemic. Towards the end of 2020, vaccination was available and promoted as an additional defence. We analysed almost three years of public COVID-19 data to determine how effective both types of strategies were in containing the pandemic across 38 European countries. We developed a statistical model to relate confirmed cases to how strict non-pharmaceutical interventions were and to vaccination levels. Both non-pharmaceutical interventions and vaccination resulted in decreased confirmed cases, although variation exists among countries. When an intervention is applied, the effect on number of confirmed cases could be seen most about fourteen days after implementation. Fajgenblat et. al utilize almost three years of COVID-19 data to model consequences of interventions across Europe. They find that both non-pharmaceutical interventions and vaccination impact daily case rates, with the strongest effect at a lag of 14 days post-implementation.M.F. acknowledges funding by the Research Foundation Flanders through an FWO PhD FR fellowship (grant number 11E3222N). T.N. acknowledges project funding by the Research Foundation Flanders (grant number G0A4121N). N.H. and C.F. acknowledge support from the EU Horizon 2020 grant EpiPose (grant number 101003688). The research presented in this paper is funded by BELSPO (Belgian Science Policy Office) in the frame of the POST-COVID programme (contract nr. TD/231/BE-PIN)
The doubling effect of COVID-19 cases on key health indicators
No full textFrom the beginning of the COVID-19 pandemic, researchers advised policy makers to make informed decisions towards the adoption of mitigating interventions. Key easy-to-interpret metrics applied over time can measure the public health impact of epidemic outbreaks. We propose a novel method which quantifies the effect of hospitalizations or mortality when the number of COVID-19 cases doubles. Two analyses are used, a country-by-country analysis and a multi-country approach which considers all countries simultaneously. The new measure is applied to several European countries, where the presence of different variants, vaccination rates and intervention measures taken over time leads to a different risk. Based on our results, the vaccination campaign has a clear effect for all countries analyzed, reducing the risk over time. However, the constant emergence of new variants combined with distinct intervention measures impacts differently the risk per country
The doubling effect of COVID-19 cases on key health indicators
No full textFrom the beginning of the COVID-19 pandemic, researchers advised policy makers to make informed decisions towards the adoption of mitigating interventions. Key easy-to-interpret metrics applied over time can measure the public health impact of epidemic outbreaks. We propose a novel method which quantifies the effect of hospitalizations or mortality when the number of COVID-19 cases doubles. Two analyses are used, a country-by-country analysis and a multi-country approach which considers all countries simultaneously. The new measure is applied to several European countries, where the presence of different variants, vaccination rates and intervention measures taken over time leads to a different risk. Based on our results, the vaccination campaign has a clear effect for all countries analyzed, reducing the risk over time. However, the constant emergence of new variants combined with distinct intervention measures impacts differently the risk per country
Souvenirs et paysages d'Orient. Smyrne -Éphèse-Magnésie- Constantinople-Scio. Par Maxime du Paris chez. Arthus Bertrand, Libraire Editeur de la Société géographique 1848.
No full textPreface: by the authorDedication: by the author to B.F., S. ad. 5Content description: Detailed contentsPagination: PP10+380PVolumes: 1Text Genre:Prose / Journa
Leveraging Massive Opportunistically Collected Datasets to Study Species Communities in Space and Time
No full textOnline portals have facilitated collecting extensive biodiversity data by naturalists, offering unprecedented coverage and resolution in space and time. Despite being the most widely available class of biodiversity data, opportunistically collected records have remained largely inaccessible to community ecologists since the imperfect and highly heterogeneous detection process can severely bias inference. We present a novel statistical approach that leverages these datasets by embedding a spatiotemporal joint species distribution model within a flexible site-occupancy framework. Our model addresses variable detection probabilities across visits and species by modelling phenological patterns and by extending the use of latent variables to characterise observer-specific detection and reporting behaviour. We apply our model to an opportunistically collected dataset on lentic odonates, encompassing over 100,000 waterbody visits in Flanders (N-Belgium), to show that the model provides insights into biological communities at high resolution, including phenology, interannual trends, environmental associations and spatiotemporal co-distributional patterns in community composition.We thank the Flemish Dragonfly Society and the many naturalists for contributing their sightings to Waarnemingen.be well as the experts of the platform's data validation team. M.F., T.N. and L.D.M. acknowledge funding by Research Foundation Flanders (FWO, grant numbers 11E3222N, G0A4121N and G0A3M24N). R.W. acknowledges a KU Leuven PhD scholarship (grant number DB/22/007/bm). L.D.M. and R.S. acknowledge financial support from a KU Leuven research project (number C16/2023/003). L.D.M. acknowledges support by an IGB starting fund. M.F., R.W., P.L. and L.D.M. acknowledge support from the PONDERFUL project, funded by the European Union's
Horizon 2020 research and innovation program under grant agreement No. 869296. The computational resources and services used in this work were provided by the VSC (Flemish Supercomputer Center), funded by the Research Foundation Flanders (FWO) and the Flemish Government
Estimating COVID-19-Related Excess Mortality Excluding Seasonal Phenomena in Belgium
No full textExcess mortality, rather than reported COVID-19 deaths has been suggested to evaluate the impact of the SARS-CoV-2 induced Corona Virus Disease (COVID-19) pandemic on mortality. However, the relationship between excess mortality and COVID-19 mortality is perturbed by seasonal phenomena, such as extreme temperatures and seasonal influenza. Models used to estimate excess mortality often ignore these underlying patterns. We propose a dynamic linear state-space model to estimate all-cause mortality, which accounts for extreme temperatures above 25°C and seasonal influenza via the Goldstein index. The state-space model prediction of the excess mortality that is not explained by heat waves and seasonal influenza coincides with the reported COVID-19 mortality in the year 2020 in Belgium.Funding
CF and NH acknowledge funding from the Epipose project from the European Union's SC1-PHECORONAVIRUS-2020 programme, project number 101003688.
Acknowledgements
We are grateful for the ability to use the Belgian data on COVID-19 confirmed deaths and seasonal influenza cases (Sciensano, Belgium). Additionally, we would like to thank the Royal Meteorological Institute (RMI) of Belgium to provide data on
temperature. The data providers hold no responsibility for the analyses reported in this manuscript
Managing African Swine Fever: Assessing the Potential of Camera Traps in Monitoring Wild Boar Occupancy Trends in Infected and Non-infected Zones, Using Spatio-Temporal Statistical Models
No full textThe recent spreading of African swine fever (ASF) over the Eurasian continent has been acknowledged as a serious economic threat for the pork industry. Consequently, an extensive body of research focuses on the epidemiology and control of ASF. Nevertheless, little information is available on the combined effect of ASF and ASF-related control measures on wild boar (Sus scrofa) population abundances. This is crucial information given the role of the remaining wild boar that act as an important reservoir of the disease. Given the high potential of camera traps as a non-invasive method for ungulate trend estimation, we assess the effectiveness of ASF control measures using a camera trap network. In this study, we focus on a major ASF outbreak in 2018-2020 in the South of Belgium. This outbreak elicited a strong management response, both in terms of fencing off a large infected zone as well as an intensive culling regime. We apply a Bayesian multi-season site-occupancy model to wild boar detection/non-detection data. Our results show that (1) occupancy rates at the onset of our monitoring period reflect the ASF infection status; (2) ASF-induced mortality and culling efforts jointly lead to decreased occupancy over time; and (3) the estimated mean total extinction rate ranges between 22.44 and 91.35%, depending on the ASF infection status. Together, these results confirm the effectiveness of ASF control measures implemented in Wallonia (Belgium), which has regained its disease-free status in December 2020, as well as the usefulness of a camera trap network to monitor these effects.sponsorship: Funding MB and MF are PhD fellows, MB is funded by a BOF-mandate at Hasselt University, MF is funded by the Research Foundation Flanders (FWO) (grant number 11E3220N). The camera trapping infrastructure was provided and funded by the Public Service of Wallonia. Services used in this work were provided by the VSC (Flemish Supercomputer Center), funded by the Research Foundation Flanders (FWO) and the Flemish Government. Finally, the ecotope dataset, used in this work, is derived from the LifeWatch ecotope database, which is led by the Earth & Life Institute (UC Louvain) and funded by the Wallonia-Brussels Federation. (y)status: Publishe
The Gut Microbiome Causally Contributes to Interspecific Differences in Pesticide Sensitivity
No full textExplaining interspecific differences in pesticide sensitivity is key to increasing the predictive power of ecotoxicology. Besides species traits, the gut microbiome may provide an untested additional predictive factor since it often plays a role in host defense against stressors. Therefore, we investigated the gut microbiome's causal role in shaping differences in pesticide sensitivity between two congeneric damselfly species. After an antibiotic treatment, reciprocal gut microbiome transplants were performed between pesticide-sensitive Ischnura elegans and more tolerant Ischnura pumilio larvae, with donor larvae first preexposed to either chlorpyrifos or a solvent control to match the subsequent pesticide treatments of the recipients. The gut microbiome, determined by 16S rRNA gene amplicon sequencing, of both species included pesticide-degrading bacteria, but also showed shared and species-specific responses to the pesticide. Notably, the most pesticide-sensitive combination, with the highest pesticide-induced mortality, consisted of I. elegans larvae receiving I. elegans donor gut microbiota, whereas the least sensitive combination consisted of I. pumilio larvae receiving I. pumilio donor gut microbiota, whereby the pesticide did not increase larval mortality. The two mixed donor-recipient gut microbiome combinations resulted in an intermediate sensitivity. Remarkably, I. elegans recipient larvae experienced a lower chlorpyrifos-induced mortality when they received an I. pumilio donor gut microbiome than when they received their conspecific I. elegans donor gut microbiome. Our results provide, to our knowledge, the first proof-of-evidence that the gut microbiome causally contributes to species differences in pesticide sensitivity.Funding
Financial support came from research grants from KU Leuven (C16/17/002) and FWO-Flanders (G.095619 and G014423N).
ACKNOWLEDGMENTS
We thank Ria Van Houdt for analytical support, and Floortje Vleugels, Geert Neyens and Rony Van Aerschot for technical support during the experiment. C.T. and M.F. are Ph.D. fellows, and J.V. a postdoctoral fellow of FWO-Flanders, N.T. is a postdoctoral fellow of the Alexander von Humboldt foundatio
- …
