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153 results for “Long-term dynamic”
Data from: Long-term dynamics of adaptation in asexual populations
Experimental studies of evolution have increased greatly in recent years, stimulated by the growing power of genomic tools. However, organismal fitness remains the ultimate metric for interpreting these experiments, and the dynamics of fitness remain poorly understood over long timescales. Here, we examine fitness trajectories for 12 Escherichia coli populations during 50,000 generations. Mean fitness appears to increase without bound, consistent with a power law. We also derive this power-law relation theoretically by incorporating clonal interference and diminishing-returns epistasis into a dynamical model of changes in mean fitness over time.
Data from: Shock and stabilisation following long-term drought in tropical forest from 15 years of litterfall dynamics
Litterfall dynamics in tropical forests are a good indicator of overall tropical forest function, indicative of carbon invested in both photosynthesising tissues and reproductive organs such as flowers and fruits. These dynamics are sensitive to changes in climate, such as drought, but little is known about the long-term responses of tropical forest litterfall dynamics to extended drought stress. We present a 15-year dataset of litterfall (leaf, flower and fruit, and twigs) from the world's only long-running drought experiment in tropical forest. This dataset comprises one of the longest published litterfall time series in natural forest, which allows the long-term effects of drought on forest reproduction and canopy investment to be explored. Over the first 4 years of the experiment, the experimental soil moisture deficit created only a small decline in total litterfall and leaf fall (12% and 13%, respectively), but a very strong initial decline in reproductive litterfall (flowers and fruits) of 54%. This loss of flowering and fruiting was accompanied by a de-coupling of all litterfall patterns from seasonal climate variables. However, following >10 years of the experimental drought, flower and fruiting re-stabilised at levels greater than in the control plot, despite high tree mortality in the drought plot. Litterfall relationships with atmospheric drivers were re-established alongside a strong new apparent trade-off between litterfall and tree growth. Synthesis. We demonstrate that this tropical forest went through an initial shock response during the first 4 years of intense drought, where reproductive effort was arrested and seasonal litterfall patterns were lost. However, following >10 years of experimental drought, this system appears to be re-stabilising at a new functional state where reproduction is substantially elevated on a per tree basis; and there is a new strong trade-off between investment in canopy production and wood production.
Data from: Parental and hybrid Daphnia from the D. longispina complex: long-term dynamics in genetic structure and significance of overwintering modes
In recent decades, hybridization has become a focus of attention because of its role in evolutionary processes. However, little is known about changes in genetic structure within and between parental species and hybrids over time. Here, we studied processes of genetic change in parental species and hybrids from the Daphnia longispina complex (Crustacea, Cladocera) over a period of six years across ten habitats. These cyclical parthenogens respond to fluctuating environments by switching from asexual to sexual reproduction. Importantly, sexually produced diapausing eggs, which resist extreme conditions such as low temperatures and serve as dispersal stages, are produced to a lower extent by hybrids. Long-term microsatellite data revealed clear differences between hybrids and parental species. In hybrids, clonal diversity values were lower, whereas heterozygosity and linkage disequilibrium values were higher compared to parental species. Clonal diversity of hybrids responded to the strength of the winter, with cold winters resulting in few genotypes in the following spring. In time windows when only asexual hybrid females survive, priority effects will favour the establishment of the hybrid offspring before hatchlings from parental diapause eggs can enter the community. The constant high levels of heterozygosity maintained by clonal reproduction in hybrids might lead to their successful establishment over time, when they are able to escape competition from both parental species. Although we found evidence that hybrids diversity depends on fluctuating environments, a direct link between hybrid abundance and the strength of winter was missing. Because of reduced adaptability in clonally reproducing hybrids, multiple factors must contribute to promoting their long-term success in fluctuating environments.
Data from: Long-term dynamics of liana seedlings suggest decelerating increases in liana relative abundance over time
<ol> <li>Over the past decades, tropical forests have experienced both compositional and structural changes. In the Neotropics, researchers at multiple sites have observed significant increases in the abundance and biomass of lianas (i.e. woody vines) relative to trees. However, the role of dynamics at early life stages in contributing to increasing liana abundance remains unclear. </li> <li>We took advantage of a unique dataset on seedling dynamics over 16 years in ~20,000 1-m<sup>2</sup>plots in a tropical forest in Panama to examine temporal and spatial trends in liana and tree seedling abundance. </li> <li>We found that the relative abundance of liana seedlings increased across the study period, from 0.18 in 2001 to 0.24 in 2017. However, increases in liana seedling relative abundance appear to have leveled off in more recent years. The observed increases in liana relative abundance appear to be the result of both higher survival and higher recruitment rates of liana seedlings compared to tree seedlings.</li> <li>Increasing liana abundance in the seedling layer was not explained by annual variation in dry season length, total rainfall, or the proportion of area occupied by canopy gaps. In addition, liana seedlings did not exhibit a demographic advantage (i.e., higher recruitment or survival) over tree seedlings in dry habitats. </li> <li> <i>Synthesis:</i>Our results reveal that seedling communities experienced important compositional changes in the past, but liana seedling relative abundance may have stabilized in recent years. Longer-term monitoring is needed to determine whether tropical forests will continue to experience compositional changes that may alter forest structure and ecosystem function. </li> </ol>
Data from: Long-term prevalence data reveals spillover dynamics in a multi-host (Artemia), multi-parasite (Microsporidia) community
In the study of multi-host parasites, it is often found that host species contribute asymmetrically to parasite transmission. Yet in natural populations, identifying which hosts contribute to parasite transmission and maintenance is a recurring challenge. Here, we approach this issue by taking advantage of natural variation in the composition of a host community. We studied the brine shrimps Artemia franciscana and Artemia parthenogenetica and their microsporidian parasites Anostracospora rigaudi and Enterocytospora artemiae. Previous laboratory experiments had shown that each host can transmit both parasites, but could not predict their actual contributions to the parasites' maintenance in the field. To resolve this, we gathered long-term prevalence data from a metacommunity of these species. Metacommunity patches could contain either or both of the Artemia host species, so that the presence of the hosts could be linked directly to the persistence of the parasites. First, we show that the microsporidian A. rigaudi is a spillover parasite: it was unable to persist in the absence of its maintenance host A. parthenogenetica. This result was particularly striking, as A. rigaudi displayed both high prevalence (in the field) and high infectivity (when tested in the laboratory) in both hosts. Moreover, the seasonal presence of A. parthenogenetica imposed seasonality on the rate of spillover, causing cyclical pseudo-endemics in the spillover host A. franciscana. Second, while our prevalence data was sufficient to identify E. artemiae as either a spillover or a facultative multi-host parasite, we could not distinguish between the two possibilities. This study supports the importance of studying the community context of multi-host parasites, and demonstrates that in appropriate multi-host systems, sampling across a range of conditions and host communities can lead to clear conclusions about the drivers of parasite persistence.
Data from: Long-term effective population size dynamics of an intensively monitored vertebrate population
Long-term genetic data from intensively monitored natural populations are important for understanding how effective population sizes (Ne) can vary over time. We therefore genotyped 1622 common buzzard (Buteo buteo) chicks sampled over 12 consecutive years (2002–2013 inclusive) at 15 microsatellite loci. This data set allowed us to both compare single-sample with temporal approaches and explore temporal patterns in the effective number of parents that produced each cohort in relation to the observed population dynamics. We found reasonable consistency between linkage disequilibrium-based single-sample and temporal estimators, particularly during the latter half of the study, but no clear relationship between annual Ne estimates (hdy201667e1gif(239)1917) and census sizes. We also documented a 14-fold increase in hdy201667e2gif(239)1917 between 2008 and 2011, a period during which the census size doubled, probably reflecting a combination of higher adult survival and immigration from further afield. Our study thus reveals appreciable temporal heterogeneity in the effective population size of a natural vertebrate population, confirms the need for long-term studies and cautions against drawing conclusions from a single sample.
Data from: Complex biotic interactions drive long-term vegetation dynamics in a subarctic ecosystem
Predicting impacts of global warming requires understanding of the extent to which plant biomass and production are controlled by bottom-up and top-down drivers. By annually monitoring community composition in grazed control plots and herbivore-free exclosures at an Arctic location for 15 years, we detected multiple biotic interactions. Regular rodent cycles acted as pulses driving synchronous fluctuations in the biomass of field-layer vegetation; reindeer influenced the biomass of taller shrubs, and the abundance of plant pathogenic fungi increased when densities of their host plants increased in exclosures. Two outbreaks of geometrid moths occurred during the study period, with contrasting effects on the field layer: one in 2004 had marginal effects, while one in 2012 severely reduced biomass in the control plots and eliminated biomass that had accumulated over 15 years in the exclosures. The latter was followed by a dramatic decline of the dominant understory dwarf-shrub Empetrum hermaphroditum, driven by an interaction between moth herbivory on top buds and leaves, and increased disease severity of a pathogenic fungus. We show that the climate has important direct and indirect effects on all these biotic interactions. We conclude that long time series are essential to identify key biotic interactions in ecosystems, since their importance will be influenced by climatic conditions, and that manipulative treatments are needed in order to obtain the mechanistic understanding needed for robust predictions of future ecosystem changes and their feedback effects.
Does salinization impact long-term Daphnia assemblage dynamics? Evidence from the sediment egg bank in a small hard-water lake
<p>Salinization of freshwater ecosystems threatens global aquatic biodiversity. There is a need for studies that follow populations <i>in situ </i>during salinization to understand the effects on species and ecosystems. We follow 170 years of <i>Daphnia </i>dynamics in the sediment ephippia archive of a small urban lake near St. Paul, Minnesota, to characterize effects of severe recent salinization on lake<i> Daphnia</i>. We found modest changes in the flux of ephippia in this lake; all three key <i>Daphnia </i>functional groups remained in the assemblage throughout the period of salinization. Reconstruction of the size distribution of <i>D. pulicaria </i>demonstrated that predation pressure by fish may not have increased for the largest and most susceptible member of the assemblage despite cultural meromixis. Our findings highlight that in hardwater lakes, the effects of salinization are nuanced and require further investigation to better understand overall impacts of salinization on lake <i>Daphnia </i>assemblages.</p>
Archive data supporting the results in the paper: Long-term soil warming alters fine root dynamics and morphology, and their ectomycorrhizal fungal community in a temperate forest soil"
<p><span>Climate warming is predicted to affect temperate forests severely, but the response of fine roots, key to plant nutrition, water uptake, soil carbon and nutrient cycling is unclear. Understanding how fine roots will respond to increasing temperature is a prerequisite for predicting the functioning of forests in a warmer climate. We studied the response of fine roots and their ectomycorrhizal (EcM) fungal and root-associated bacterial communities to soil warming by 4 °C in a mixed spruce-beech forest in the Austrian Limestone Alps after 8 and 14 years of soil warming, respectively. Fine root biomass (FRB) and fine root production were 17% and 128% higher in the warmed plots, respectively, after 14 years. The increase in FRB (13%) was not significant after 8 years of treatment, whereas specific root length, specific root area, and root tip density were significantly higher in warmed plots at both sampling occasions. Soil warming did not affect EcM exploration types and diversity, but changed their community composition, with an increase in the relative abundance of <em>Cenoccocum</em> at 0 – 10 cm soil depth, a drought-stress tolerant genus, and an increase in short and long-distance exploration types like <em>Sebacina </em>and <em>Boletus </em>at 10 – 20 cm soil depth. Warming increased the root-associated bacterial diversity but did not affect their community composition. Soil warming did not affect nutrient concentrations of fine roots, though we found indications of limited soil phosphorus (P) and potassium (K) availability. </span><span>Our findings suggest that, in the studied ecosystem, global warming could persistently increase soil carbon inputs due to accelerated fine root growth and turnover, and could simultaneously alter fine root morphology and EcM fungal community composition towards improved nutrient foraging. </span></p>
Experimental data for: Long-term memory and synapse-like dynamics in two-dimensional nanofluidic channels
<p>Experimental data set for: Long-term memory and synapse-like dynamics in two-dimensional nanofluidic channels. Provides all raw data needed to reproduce experimental graphs presented within the paper.</p>
Competition dynamics in long-term propagations of Schizosaccharomyces pombe strain communities
<p>Experimental evolution studies with microorganisms such as bacteria and yeast have been an increasingly important and powerful tool to draw long-term inferences of how microbes interact. However, while several strains of the same species often exist in natural environments, many ecology and evolution studies in microbes are typically performed with isogenic populations of bacteria or yeast. In the present study, we firstly perform a genotypic and phenotypic characterization of two lab and eight natural strains of the yeast <i>Schizosaccharomyces pombe</i>. We then propagated, in a rich resource environment, yeast communities of 2-, 3-, 4- and 5-strains for hundreds of generations and asked which fitness related phenotypes – maximum growth rate or relative competitive fitness – would better predict the outcome of a focal strain during the propagations. While the strain's growth rates would wrongly predict long-term co-existence, pairwise competitive fitness with a focal strain qualitatively predicted the success or extinction of the focal strain by a simple multi-genotype population genetics model, given the initial community composition. Interestingly, we have also measured the competitive fitness of the ancestral and evolved communities by the end of the experiment (≈370 generations) and observed frequent maladaptation to the abiotic environment in communities with more than three members. Overall, our results aid establishing pairwise competitive fitness as good qualitative measurement of long-term community composition but also reveal a complex adaptive scenario when trying to predict the evolutionary outcome of those communities.</p>
Fig. 2 in Long-term dynamics of microplastic accumulation in the intestinal tract of terrestrial insects on the example of Vespula vulgaris (Linnaeus, 1758) (Hymenoptera: Vespidae)
Fig. 2. Occurrence of different types of MPs inside wasps, %. Рис. 2. Встречаемость раЗнотипных частиц МП в осах, %.
Fig. 1 in Long-term dynamics of microplastic accumulation in the intestinal tract of terrestrial insects on the example of Vespula vulgaris (Linnaeus, 1758) (Hymenoptera: Vespidae)
Fig. 1. Box and whisker plot showing average content of MP particles inside wasps from natural populations sampled in the vicinity of the village of Kireevsk (five samples/year; Tomsk region, Russia). Рис. 1. Диаграмма, демонстрируюЩаЯ среднее содержание частиц МП в осах иЗ природных популЯций (5 выборок/год) в окрестностЯх с. Киреевск (ТомскаЯ область, РоссиЯ).
Data from: Temperature effects on long-term population dynamics in a parasitoid-host system
Long-term environmental changes will likely alter the strengths of interactions between species and consequently their population dynamics, leading to changes in the stability of ecological systems. While an increasing number of empirical studies have shown that environmental changes can alter the strengths of species interactions, these studies are typically short (<1–2 generations) and therefore give only partial information about longer term population dynamics. To focus on longer term dynamics, we investigated population cycles of pea aphids and their most common parasitoid, Aphidius ervi, in Wisconsin, USA. Data collected over three years in alfalfa fields showed an apparent host–parasitoid population cycle. Furthermore, higher pea aphid population growth rates and increased parasitism were correlated with higher naturally occurring temperatures. While these effects were observed with seasonal fluctuations in temperature, they beg the question of how long-term changes in mean annual temperature might change aphid–parasitoid population cycles, a question which we further pursued with laboratory experiments. To quantify temperature-dependent demographic parameters, we used short-term (<1 generation) experiments conducted at 20°C and 27°C. The higher temperature increased aphid and parasitoid development rates, adult aphid life span and fecundity, and parasitoid attack rates. We then conducted multi-generation population-level laboratory experiments to reveal the effects of temperature (20°C vs. 27°C) on population dynamics. We fit the resulting time series data using a nonlinear age-structured state-space model to estimate population-level processes that could not be estimated in short-term laboratory experiments. Using the model, we parsed out the demographic rates that had the largest impacts on aphid–parasitoid population cycles. This analysis showed that there were frequent contrasts in the effects of temperature operating through different demographic rates. For example, the temperature-dependent increase in aphid development rate decreased cycle amplitude, while the increase in parasitoid attack rate increased cycle amplitude. There were also striking interactions among demographic rates. For example, the temperature-dependent increase in aphid development rate could either increase or decrease the cycle period depending on the values of other demographic rates. Although these complexities make predictions difficult, overall they suggest that increasing long-term mean temperature will decrease the period, increase the amplitude, and tend to destabilize pea aphid–A. ervi dynamics.
Capturing the dynamics of small populations: A retrospective assessment using long-term data for an island reintroduction
<p>1. The art of population modelling is to incorporate factors essential for capturing a population's dynamics while otherwise keeping the model as simple as possible. However, it is unclear how optimal model complexity should be assessed, and whether this optimal complexity has been affected by recent advances in modelling methodology. This issue is particularly relevant to small populations because they are subject to complex dynamics but inferences about those dynamics are often constrained by small sample sizes.</p> <p>2. We fitted Bayesian hierarchical models to long-term data on vital rates (survival and reproduction) for the toutouwai (Petroica longipes) population reintroduced to Tiritiri Matangi, a 220-ha New Zealand island, and quantified the performance of those models in terms of their likelihood of replicating the observed population dynamics. These dynamics consisted of overall growth from 33 (± 0.3) to 160 (± 6) birds from 1992–2018, including recoveries following five harvest events for further reintroductions to other sites.</p> <p>3. We initially included all factors found to affect vital rates, which included inbreeding, post-release effects, density-dependence, sex, age and random annual variation, then progressively removed these factors. We also compared performance of models where data analysis and simulations were done simultaneously to those produced with the traditional two-step approach, where vital rates are estimated first then fed into a separate simulation model. Parametric uncertainty and demographic stochasticity were incorporated in all projections.</p> <p>4. The essential factors for replicating the population's dynamics were density-dependence in juvenile survival and post-release effects, i.e. initial depression of survival and reproduction in translocated birds. Inclusion of other factors reduced the precision of projections, and therefore the likelihood of matching observed dynamics. However, this reduction was modest when the modelling was done in an integrated framework. In contrast, projections were much less precise when done with a two-step modelling approach, and the cost of additional parameters was much higher under the two-step approach.</p> <p>5. These results suggest that minimization of complexity may be less important than accounting for covariances in parameter estimates, which is facilitated by integrating data analysis and population projections using Bayesian methods. 13-Aug-2021 --</p>
Prognostic Model for Long-Term Cardiac Function After Pulmonary Embolism Based on Dynamic Electrocardial Signal and Circulating Biomarkers
ClinicalTrials.gov study NCT06541353. IPD Sharing: Not stated. Countries: 1. Publications: 0.
Data from: Long-term dynamics of adaptation in asexual populations
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Competition dynamics in long-term propagations of Schizosaccharomyces pombe strain communities
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Data from: Complex biotic interactions drive long-term vegetation dynamics in a subarctic ecosystem
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Long-term population dynamics of an insect in a simple food web under a changing environment
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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.