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795 results for “fluctuations”
Data from: Fluctuating temperature leads to evolution of thermal generalism and preadaptation to novel environments
Environmental fluctuations can select for generalism, which is also hypothesized to increase organisms' ability to invade novel environments. Here, we show that across a range of temperatures, opportunistic bacterial pathogen Serratia marcescens that evolved in fluctuating temperature (daily variation between 24°C and 38°C, mean 31°C) outperforms the strains that evolved in constant temperature (31°C). The growth advantage was also evident in novel environments in the presence of parasitic viruses and predatory protozoans, but less clear in the presence of stressful chemicals. Adaptation to fluctuating temperature also led to reduced virulence in Drosophila melanogaster host, which suggests that generalism can still be costly in terms of reduced fitness in other ecological contexts. While supporting the hypothesis that evolution of generalism is coupled with tolerance to several novel environments, our results also suggest that thermal fluctuations driven by the climate change could affect both species' invasiveness and virulence.
Data from: Critical thermal limits affected differently by developmental and adult thermal fluctuations
Means and variances of the environmental thermal regime play an important role in determining the fitness of terrestrial ectotherms. Adaptive phenotypic responses induced by heterogeneous temperatures have been shown to be mediated by molecular pathways independent of the classic heat shock responses, however, an in-depth understanding of plasticity induced by fluctuating temperatures is still lacking. We investigated high and low temperature acclimation induced by fluctuating thermal regimes at two different mean temperatures, at two different amplitudes of fluctuation and across the developmental and adult life stages. For developmental acclimation, we found mildly detrimental effects of high amplitude fluctuations for critical thermal minima, while the critical thermal maxima showed a beneficial response to higher amplitude fluctuations. For adult acclimation involving shifts between fluctuating and constant regimes, cold tolerance was shown to be dictated by developmental temperature conditions irrespective of the adult treatments, while the acquired heat tolerance was readily lost when flies developed at fluctuating temperature were shifted to a constant regime as adults. Interestingly, we also found that effect of fluctuations at any life stage was gradually lost with prolonged adult maintenance suggesting a more prominent effect of fluctuations during developmental compared to adult acclimation in Drosophila melanogaster.
Data from: Overestimation of the adaptive substitution rate in fluctuating populations
Estimating the proportion of adaptive substitutions (α) is of primary importance to uncover the determinants of adaptation in comparative genomic studies. Several methods have been proposed to estimate α from patterns polymorphism and divergence in coding sequences. However, estimators of α can be biased when the underlying assumptions are not met. Here we focus on a potential source of bias, i.e., variation through time in the long term population size (N) of the considered species. We show via simulations that ancient demographic fluctuations can generate severe overestimations of α, and this irrespective of the recent population history.
Data from: The plastic fly: the effect of sustained fluctuations in adult food supply on life history traits
Many adult traits in Drosophila melanogaster show phenotypic plasticity, and the effects of diet on traits such as lifespan and reproduction are well explored. Although plasticity in response to food is still present in older flies, it is unknown how sustained environmental variation affects life-history traits. Here, we explore how such life-long fluctuations of food supply affect weight and survival in groups of flies and affect weight, survival and reproduction in individual flies. In both experiments, we kept adults on constant high or low food and compared these to flies that experienced fluctuations of food either once or twice a week. For these 'yoyo' groups, the initial food level and the duration of the dietary variation differed during adulthood, creating four 'yoyo' fly groups. In groups of flies, survival and weight were affected by adult food. However, for individuals, survival and reproduction, but not weight, were affected by adult food, indicating that single and group housing of female flies affects life-history trajectories. Remarkably, both the manner and extent to which life-history traits varied in relation to food depended on whether flies initially experienced high or low food after eclosion. We therefore conclude that the expression of life-history traits in adult life is affected not only by adult plasticity, but also by early adult life experiences. This is an important but often overlooked factor in studies of life-history evolution and may explain variation in life-history experiments.
Data from: Intraspecific variability in growth response to environmental fluctuations modulates the stabilizing effect of species diversity on forest growth
1.Differences between species in their response to environmental fluctuations cause asynchronized growth series, suggesting that species diversity may help communities buffer the effects of environmental fluctuations. However, within-species variability of responses may impact the stabilizing effect of growth asynchrony. 2.We used tree ring data to investigate the diversity-stability relationship and its underlying mechanisms within the temperate and boreal mixed woods of Eastern Canada. We worked at the individual tree level to take into account the intraspecific variability of responses to environmental fluctuations. 3.We found that species diversity stabilized growth in forest ecosystems. The asynchrony of species' response to climatic fluctuations and to insect outbreaks explained this effect. We also found that the intraspecific variability of responses to environmental fluctuations was high, making the stabilizing effect of diversity highly variable. 4.Synthesis. Our results are consistent with previous studies suggesting that the asynchrony of species' response to environmental fluctuations drives the stabilizing effect of diversity. The intraspecific variability of these responses modulates the stabilizing effect of species diversity. Interactions between individuals, variation in tree size and spatial heterogeneity of environmental conditions could play a critical role in the stabilizing effect of diversity.
Data from: The rate of environmental fluctuations shapes ecological dynamics in a two-species microbial system
Species interactions change when the external conditions change. How these changes affect microbial community properties is an open question. We address this question using a two-species consortium in which species interactions change from exploitation to competition depending on the carbon source provided. We built a mathematical model and calibrated it using single-species growth measurements. This model predicted that low frequencies of change between carbon sources lead to species loss, while intermediate and high frequencies of change maintained both species. We experimentally confirmed these predictions by growing co-cultures in fluctuating environments. These findings complement more established concepts of a diversity peak at intermediate disturbance frequencies. They also provide a mechanistic understanding for how the dynamics at the community level emerges from single-species behaviors and interspecific interactions. Our findings suggest that changes in species interactions can profoundly impact the ecological dynamics and properties of microbial systems.
Data from: Impacts of dispersal on rapid adaptation and dynamic stability of Daphnia in fluctuating environments
Prior ecological research has shown that spatial processes can enhance the temporal stability of populations in fluctuating environments. Less explored is the effect of dispersal on rapid adaptation and its concomitant impact on population dynamics. For asexually reproducing populations, theory predicts that dispersal in fluctuating environments can facilitate asynchrony among clones and enhance stability by reducing temporal variability of total population abundance. This effect is predicted when clones exhibit heritable variation in environmental optima and when fluctuations occur asynchronously among patches. We tested this in the field using artificial ponds and metapopulations composed of a diverse assemblage of <i>Daphnia pulex</i> clones. We directly manipulated dispersal presence/absence and environmental fluctuations in the form of nutrient pulses. Consistent with predictions, dispersal enhanced temporal asynchrony among clones in the presence of nutrient pulses; this in turn stabilized population dynamics. This effect only emerged when patches experienced spatially asynchronous nutrient pulses (dispersal had no effect when patches were synchronously pulsed). Clonal asynchrony was driven by strong positive selection for a single clone that exhibited a performance advantage under conditions of low resource availability. Our work highlights the importance of dispersal as a driver of eco-evolutionary dynamics and population stability in variable environments.
Data from: Fluctuating seawater pH/ p CO 2 regimes are more energetically expensive than static pH/ p CO 2 levels in the mussel Mytilus edulis
Ocean acidification (OA) studies typically use stable open-ocean pH or CO2 values. However, species living within dynamic coastal environments can naturally experience wide fluctuations in abiotic factors, suggesting their responses to stable pH conditions may not be reflective of either present or near-future conditions. Here we investigate the physiological responses of the mussel Mytilus edulis to variable seawater pH conditions over short- (6 h) and medium-term (2 weeks) exposures under both current and near-future OA scenarios. Mussel haemolymph pH closely mirrored that of seawater pH over short-term changes of 1 pH unit with acidosis or recovery accordingly, highlighting a limited capacity for acid–base regulation. After 2 weeks, mussels under variable pH conditions had significantly higher metabolic rates, antioxidant enzyme activities and lipid peroxidation than those exposed to static pH under both current and near-future OA scenarios. Static near-future pH conditions induced significant acid–base disturbances and lipid peroxidation compared with the static present-day conditions but did not affect the metabolic rate. These results clearly demonstrate that living in naturally variable environments is energetically more expensive than living in static seawater conditions, which has consequences for how we extrapolate future OA responses in coastal species.
Data from: Strategic exploitation of fluctuating asymmetry in male Endler's guppy courtship displays is modulated by social environment
Lateral asymmetry in signalling traits enables males to strategically exploit their best side. In many animals, both body colouration and fluctuating asymmetry are signals of male attractiveness. We demonstrated experimentally that even sexually naïve male Poecilia wingei were able to identify their most attractive side (i.e. that with a higher proportion of carotenoid pigmentation) and use it preferentially during courtship. Notably, males retained their strategic signalling in a male-biased social environment, whereas they ceased to signal strategically in a female-biased environment. The degree of asymmetry in colouration did not affect overall courtship activity. Strategic lateralization in courtship displays was strongest and most repeatable in the male-biased social environment where males competed with rivals for matings. Individual asymmetry in colouration changed considerably over a period of 3 months. This suggests that colouration is a dynamic feature during adulthood and that males are capable of tracking and strategically exploiting their lateral asymmetry in accordance with their social environment.
Data from: Thermal fluctuations affect the transcriptome through mechanisms independent of average temperature
Terrestrial ectotherms are challenged by variation in both mean and variance of temperature. Phenotypic plasticity (thermal acclimation) might mitigate adverse effects, however, we lack a fundamental understanding of the molecular mechanisms of thermal acclimation and how they are affected by fluctuating temperature. Here we investigated the effect of thermal acclimation in Drosophila melanogaster on critical thermal maxima (CTmax) and associated global gene expression profiles as induced by two constant and two ecologically relevant (non-stressful) diurnally fluctuating temperature regimes. Both mean and fluctuation of temperature contributed to thermal acclimation and affected the transcriptome. The transcriptomic response to mean temperatures comprised modification of a major part of the transcriptome, while the response to fluctuations affected a much smaller set of genes, which was highly independent of both the response to a change in mean temperature and to the classic heat shock response. Although the independent transcriptional effects caused by fluctuations were relatively small, they are likely to contribute to our understanding of thermal adaptation. We provide evidence that environmental sensing, particularly phototransduction, is a central mechanism underlying the regulation of thermal acclimation to fluctuating temperatures. Thus, genes and pathways involved in phototransduction are likely of importance in fluctuating climates.
Data from: Continuous high and low temperature induced a decrease of photosynthetic activity and changes in the diurnal fluctuations of organic acids in Opuntia streptacantha
Opuntia plants grow naturally in areas where temperatures are extreme and highly variable in the day during the entire year. These plants survive through different adaptations to respond to adverse environmental conditions. Despite this capability, it is unknown how CAM photosynthetic activity and growth in Opuntia plantlets is affected by constant heat or cold. Therefore, the main objective of this research was to evaluate the short-term effect of high (40°C) and low (4°C) continuous temperatures on the photosynthetic efficiency, the organic acid content (malic acid) and the relative growth rate (RGR) in seven-month-old Opuntia streptacantha plantlets during 5, 10, and 15 days. Chlorophyll fluorescence analysis allowed us to determine that high temperatures negatively impact the photosynthetic efficiency of O. streptacantha plantlets, which exhibited the lowest values of maximum quantum efficiency of the photosystem II (Fv/Fm = 52%, Fv/F0 = 85%), operational quantum yield of PS (ΦPSII = 65%) and relative electron transport rate (rETR = 65%), as well as highest values of basal fluorescence (F0 = 226%) during 15 days of treatment. Similarly, low temperatures decreased Fv/Fm (16%), Fv/F0 (50%), ΦPSII and rETR (16%). High temperatures also decreased nocturnal acidification in approximately 34–50%, whereas low temperatures increased it by 30–36%. Additionally, both continuous temperatures affected drastically diurnal consumption of malic acid, which was related to a significant RGR inhibition, where the specific photosynthetic structure area component was the most affected. Our results allowed determining that, despite the high tolerance to extreme temperatures described for Opuntia plants, young individuals of O. streptacantha suffered photosynthetic impairment that led to the inhibition of their growth. Thus, the main findings reported in this study can help to predict the potential impact of climatic change on the establishment and survival of succulent species of arid and semiarid regions of Mexico.
Data from: Large fluctuations in the effective population size of the malaria mosquito Anopheles gambiae s.s. during vector control cycle
On Bioko Island, Equatorial Guinea, indoor residual spraying (IRS) has been part of the Bioko Island Malaria Control Project since early 2004. Despite success in reducing childhood infections, areas of high transmission remained on the island. We therefore examined fluctuations in the effective population size (N_e) of the malaria vector Anopheles gambiae in an area of persistent high transmission over two spray rounds. We analyzed data for 13 microsatellite loci from 791 An. gambiae specimens collected at 6 time points in 2009 and 2010 and reconstructed the demographic history of the population during this period using Approximate Bayesian Computation (ABC). Our analysis shows that IRS rounds have a big impact on N_e, reducing it by 65% to 92% from pre-spray round N_e. More importantly our analysis shows that after 3-5 months, the An. gambiae population rebounded by 2,818% compared to shortly following the spray round. Our study underscores the importance of adequate spray round frequency to provide continuous suppression of mosquito populations, and that increased spray round frequency should substantially improve the efficacy of IRS campaigns. It also demonstrates the ability of ABC to reconstruct a detailed demographic history across only a few tens of generations in a large population.
Skeletonema marinoi eco-types show specific habitat-related responses to fluctuating light supporting high potential for growth under photobioreactor light regime
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Fig. 1 in Fluctuating Asymmetry As A Tool In Identifying Population Stress In Hungarian Populations Of Bombina Bombina, B. Variegata And Their Hybrids
Fig. 1. Mean asymmetry compared among the two pure species and their hybrids for: a) femur and b) tibia length. Bars represent 95% confidence intervals
Fig. 4 in Spatial patterns of zooplanktivore Chirostoma species (Atherinopsidae) during water-level fluctuation in the shallow tropical Lake Chapala, Mexico: seasonal and interannual analysis
Fig. 4. GAM results for May of species correlation influence on fish density. a: effect of Chirostoma jordani on C. consocium; b: effect of C. jordani on C. labarcae; c: effect of C. labarcae on C. consocium. Circles represent the residuals. Spline fit (solid line) is bound by 95% confidence intervals (dotted lines).
Data Repo for "Crossover of high-energy spin fluctuations from collective triplon excitations to incoherent gapped magnetic modes in the cuprate ladders of Sr14-xCaxCu24O41"
<p>Data set for the paper "Crossover of high-energy spin fluctuations from collective triplon excitations to incoherent gapped magnetic modes in the cuprate ladders of Sr14-xCaxCu24O41"</p> <p>Preprint Available at: https://arxiv.org/abs/2201.05027</p> <p> </p>
Visualization and analysis of membrane fluctuation
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Effects of pH/pCO2 fluctuation on photosynthesis and fatty acid composition of two marine diatoms
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Non-invasive monitoring of a reactive soil transition zone during water table fluctuations using spectral induced polarization (SIP) and electrodic potential (EP)
<p>Transition zones separating the unsaturated and saturated domains in soils are a hotspot for biogeochemical activity. They are challenging to study because they are dynamic, requiring high resolution temporal and spatial data acquisition methods to capture the biogeochemical processes across the water table. Non-invasive geophysical techniques, such as spectral induced polarization (SIP) and electrodic potential (EP), offer comparatively inexpensive monitoring approaches that yield data on changes in soil electrical properties, driven by reactive processes at high spatial and temporal resolutions. We investigated SIP and EP signal variations in artificial soil-filled columns, experiencing periodic water table fluctuations in order to: (1) assess the effectiveness of SIP and EP in monitoring a complex soil transition zone, and (2) couple the measured geophysical signals to changes in physical, chemical and microbial properties. SIP responses showed a clear dependence on the depth-distribution of microbial biomass. Dynamic imaginary conductivity (<em>σ''</em>) responses were only detected in the water table fluctuation zone and, in contrast to real conductivity (<em>σ'</em>) data, did not exhibit a direct soil moisture driven dependence. We attribute the observed dynamics in <em>σ'' </em>to microbially driven reactions. An EP anomaly arose concurrent to the production of SO<sub>4</sub><sup>2- </sup>as a result of oxygenation at depth during drainage of the columns. Our findings show that continuous SIP and EP signals, in conjunction with periodic measurements of geochemical indicators, can help determine the location and temporal variability of biogeochemical activity and be used to monitor targeted reaction zones and pathways in complex soil environments.</p>
Dynamical charge density fluctuations pervading the phase diagram of a Cu-based high-Tc superconductor
<p>[This repository contains the raw data for the manuscript "<strong>Dynamical charge density fluctuations pervading the phase diagram of a Cu-based high-Tc superconductor</strong>" (arXiv:1809.04949)]</p> <p>Charge density modulations are a common occurrence in all families of high critical temperature superconducting cuprates. Although consistently observed in the underdoped region of the phase diagram and at relatively low temperatures, it is still unclear to what extent they influence the unusual properties of these systems. Using resonant x-ray scattering we carefully determined the temperature dependence of charge density modulations in YBa<sub>2</sub>Cu<sub>3</sub>O<sub>7-δ</sub> and Nd<sub>1+x</sub>Ba<sub>2-x</sub>Cu<sub>3</sub>O<sub>7-δ</sub> for several doping levels. We discovered short-range dynamical charge density fluctuations besides the previously known quasi-critical charge density waves. They persist up to well above the pseudogap temperature <em>T*</em>, are characterized by energies of few meV and pervade a large area of the phase diagram, so that they can play a key role in shaping the peculiar normal-state properties of cuprates.</p>
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Allen Brain Atlas
Allen Brain Atlas is an Allen Institute collection of brain map atlases, datasets, APIs, and analysis tools covering mouse, human, and non-human primate brain resources.
Annotated Behaviour and Observability Dataset (ABODe)
ABODe is a University of Edinburgh DataShare dataset for behavior classification in group-housed mice using home-cage video, identities, bounding boxes, ground-plate positions, and annotator labels.
DANDI Archive for NWB datasets
DANDI is a BRAIN Initiative archive for publishing and sharing neurophysiology data, including electrophysiology, optophysiology, and behavioral data packaged as NWB and related standards.
International Brain Laboratory public data
The International Brain Laboratory public data releases expose standardized mouse decision-making experiments, including Neuropixels recordings, widefield calcium imaging, behavior, and session metadata accessed through the ONE API.
OpenNeuro
OpenNeuro is a free, open platform for sharing neuroimaging datasets, with public search, dataset pages, and download paths for web, S3, DataLad, and the OpenNeuro CLI.