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3,339 results for “heterogeneities”
Data from: Microhabitat heterogeneity and a non-native avian frugivore drive the population dynamics of an island endemic shrub, Cyrtandra dentata
Understanding of the role of environmental change in the decline of endangered species is critical to designing scale-appropriate restoration plans. For locally endemic rare plants on the brink of extinction, frugivory can drastically reduce local recruitment by dispersing seeds away from geographically isolated populations. Dispersal of seeds away from isolated populations can ultimately lead to population decline. For localized endemic plants, fine-scale changes in microhabitat can further limit population persistence. Evaluating the individual and combined impact of frugivores and microhabitat heterogeneity on the short-term (i.e. transient) and long-term (i.e. asymptotic) dynamics of plants will provide insight into the drivers of species rarity. In this study, we used four years of demographic data to develop matrix projection models for a long-lived shrub, Cyrtandra dentata (H. St. John & Storey) (Gesneriaceae), which is endemic to the island of O'ahu in Hawai'i. Furthermore, we evaluated the individual and combined influence of a non-native frugivorous bird, Leiothrix lutea, and microhabitat heterogeneity on the short-term and long-term C. dentata population dynamics. Frugivory by L. lutea decreased the short-term and long-term population growth rates. However, under the current level of frugivory at the field site the C. dentata population was projected to persist over time. Conversely, the removal of optimum microhabitat for seedling establishment (i.e. rocky gulch walls and boulders in the gulch bottom) reduced the short-term and long-term population growth rates from growing to declining. Survival of mature C. dentata plants had the greatest influence on long-term population dynamics, followed by the growth of seedlings and immature plants. The importance of mature plant survival was even greater when we simulated the combined effect of frugivory and the loss of optimal microhabitat, relative to population dynamics based on field conditions. In the short-term (10 years), however, earlier life stages had the greatest influence on population growth rate. Synthesis and applications. This study emphasizes how important it is to decouple rare plant management strategies in the short versus long-term in order to prioritize restoration actions, particularly when faced with multiple stressors not all of which can be feasibly managed. From an applied conservation perspective, our findings also illustrate that the life stage that, if improved by management, would have the greatest influence on population dynamics is dependent on the timeframe of interest and initial conditions of the population.
Data from: Spatially heterogeneous perturbations homogenize the regulation of insect herbivores
Anthropogenic influences on resources and consumers can affect food web regulation, with impacts on trophic structure and ecosystem processes. Identifying how these impacts unfold is challenging because alterations to one or both resources and consumers can similarly transform community structure, especially for intermediate consumers. To date, empirical testing of perturbations on trophic regulation has been limited by the difficulty in separating the direct effect of perturbations on species composition and diversity from those unfolding indirectly via altered feeding pathways. Moreover, disentangling the independent and interactive impacts of covarying stressors that characterize human-altered systems has been an ongoing analytical challenge. We used a large-scale metacommunity experiment in grasslands to test how resource inputs, stand perturbation, and spatial factors affect regulation of insect herbivores in tritrophic grassland food webs. Using path-model comparisons, we observed significant simplification of food web regulation on insect herbivores, shifting from mixed predator-resource regulation in unaltered mainland areas to strictly resource-based regulation with landscape perturbation and fragmentation. Most changes were attributed to homogenization of plant community caused by landscape fragmentation and the deterministic influence of eutrophication that reduced among-patch beta diversity. This led to a simplified food web dominated by fewer but more abundant herbivore taxa. Our work implies that anthropogenic perturbation relating to resources and spatial isolation can transform the regulation of food web diversity, structure, and function.
Data from: Heterogeneous genomic differentiation in marine threespine sticklebacks: adaptation along an environmental gradient
Evolutionary divergence among populations occupying ecologically distinct environments can occur even in the face of on-going gene flow. However, the genetic underpinnings, as well as the scale and magnitude at which this differentiation occurs in marine habitats are not well understood. We investigated the patterns and degree of genomic heterogeneity in threespine sticklebacks (Gasterosteus aculeatus) by assessing genetic variability in 20 nongenic and 20 genic (associated with genes important for freshwater adaptation) microsatellite loci in samples collected from 38 locations spanning the entire Baltic Sea coast to the North Sea boundary. Population divergence (FST ≈ 0.026) and structuring (five genetic clusters) was significantly more pronounced in the genic as compared to nongenic markers (FST ≈ 0.008; no genetic clusters). Patterns of divergence in the genic markers—45% of which were identified as outliers—correlated with local differences in salinity. Yet, a strong positive correlation between divergence in genic and nongenic markers, and their association with environmental factors suggests that adaptive divergence is reducing gene flow across the genome. Apart from providing a clear demonstration of heterogeneous genomic patterns of differentiation in a marine species, the results are indicative of adaptive population structuring across the relatively young Baltic Sea in spite of ample opportunities for gene flow.
Data from: Highly diverse and spatially heterogeneous mycorrhizal symbiosis in a rare epiphyte is unrelated to broad biogeographic or environmental features
Symbiotic interactions are common in nature. In dynamic or degraded environments, the ability to associate with multiple partners (i.e. broad specificity) may enable species to persist through fluctuations in the availability of any particular partner. Understanding how species interactions vary across landscapes is necessary to anticipate direct and indirect consequences of environmental degradation on species conservation. We asked whether mycorrhizal symbiosis by populations of a rare epiphytic orchid (Epidendrum firmum) is related to geographic or environmental heterogeneity. The latter would suggest that interactions are governed by environmental conditions rather than historic isolation of populations and/or mycorrhizal fungi. We used DNA-based methods to identify mycorrhizal fungi from eleven E. firmum populations in Costa Rica. We used molecular and phylogenetic analyses to compare associations. Epidendrum firmum exhibited broad specificity, associating with diverse mycorrhizal fungi, including six Tulasnellaceae molecular operational taxonomic units (MOTUs), five Sebacinales MOTUs and others. Notably, diverse mycorrhizal symbioses formed in disturbed pasture and roadside habitats. Mycorrhizal fungi exhibited significant similarity within populations (spatial and phylogenetic autocorrelation) and significant differences among populations (phylogenetic community dissimilarity). However, mycorrhizal symbioses were not significantly associated with biogeographic or environmental features. Such unexpected heterogeneity among populations may result from complex combinations of fine-scale environmental factors and macro-evolutionary patterns of change in mycorrhizal specificity. Thus, E. firmum exhibits broad specificity and the potential for opportunistic associations with diverse fungi. We suggest that these characteristics could confer symbiotic assurance when mycorrhizal fungi are stochastically available, which may be crucial in dynamic or disturbed habitats such as tropical forest canopies.
Data from: Heterogeneity of genetic architecture of body size traits in a free-living population
Knowledge of the underlying genetic architecture of quantitative traits could aid in understanding how they evolve. In wild populations, it is still largely unknown whether complex traits are polygenic or influenced by few loci with major effect, due to often small sample sizes and low resolution of marker panels. Here, we examine the genetic architecture of five adult body size traits in a free-living population of Soay sheep on St Kilda using 37 037 polymorphic SNPs. Two traits (jaw and weight) show classical signs of a polygenic trait: the proportion of variance explained by a chromosome was proportional to its length, multiple chromosomes and genomic regions explained significant amounts of phenotypic variance, but no SNPs were associated with trait variance when using GWAS. In comparison, genetic variance for leg length traits (foreleg, hindleg and metacarpal) was disproportionately explained by two SNPs on chromosomes 16 (s23172.1) and 19 (s74894.1), which each explained >10% of the additive genetic variance. After controlling for environmental differences, females heterozygous for s74894.1 produced more lambs and recruits during their lifetime than females homozygous for the common allele conferring long legs. We also demonstrate that alleles conferring shorter legs have likely entered the population through a historic admixture event with the Dunface sheep. In summary, we show that different proxies for body size can have very different genetic architecture and that dense SNP helps in understanding both the mode of selection and the evolutionary history at loci underlying quantitative traits in natural populations.
Data from: Patterns of cyto-nuclear linkage disequilibrium in Silene latifolia: genomic heterogeneity and temporal stability
Non-random association of alleles in the nucleus and cytoplasmic organelles, or cyto-nuclear linkage disequilibrium (LD), is both an important component of a number of evolutionary processes and a statistical indicator of others. The evolutionary significance of cyto-nuclear LD will depend on both its magnitude and how stable those associations are through time. Here, we use a longitudinal population genetic data set to explore the magnitude and temporal dynamics of cyto-nuclear disequilibria through time. We genotyped 135 and 170 individuals from 16 and 17 patches of the plant species Silene latifolia in Southwestern VA, sampled in 1993 and 2008, respectively. Individuals were genotyped at 14 highly polymorphic microsatellite markers and a single-nucleotide polymorphism (SNP) in the mitochondrial gene, atp1. Normalized LD (D′) between nuclear and cytoplasmic loci varied considerably depending on which nuclear locus was considered (ranging from 0.005–0.632). Four of the 14 cyto-nuclear associations showed a statistically significant shift over approximately seven generations. However, the overall magnitude of this disequilibrium was largely stable over time. The observed origin and stability of cyto-nuclear LD is most likely caused by the slow admixture between anciently diverged lineages within the species' newly invaded range, and the local spatial structure and metapopulation dynamics that are known to structure genetic variation in this system.
Data from: Environmental heterogeneity leads to higher plasticity in dry-edge populations of a semiarid Chilean shrub: insights into climate change responses
1.Interannual variability in climatic conditions should be taken into account in climate change studies in semiarid ecosystems. It may determine differentiation in phenotypic plasticity among populations, with populations experiencing higher environmental heterogeneity showing higher levels of plasticity. 2.The ability of populations to evolve key functional traits and plasticity may determine the survival of plant populations under the drier and more variable climate expected for semiarid ecosystems. 3.Working with populations of the semiarid Chilean shrub Senna candolleana along its entire distribution range, we assessed inter- and intra-population variation in functional traits as well as in their plasticity in response to water availability. We measured morphological and physiological traits related to drought resistance in both field conditions and in a greenhouse experiment, where drought response was evaluated under two water availability treatments. 4.All populations responded plastically, but higher precipitation heterogeneity in dry-edge populations seemed to have selected for more plastic genotypes compared to populations growing at mesic sites and with more homogeneous environmental conditions. 5.Synthesis: Our results suggest adaptive plasticity since higher levels of phenotypic plasticity were positively associated with plant performance. However, we did not find evidence for genetic variation for plasticity within populations. To the extent that phenotypic plasticity may play a key role in future persistence, populations at mesic sites may be more vulnerable to climate change due to their lower plasticity and their current limitations to evolve novel norms of reaction. Conversely, although Senna candolleana populations at the dry-edge are exposed to higher levels of stress, they may be less susceptible to climate change in view of their greater plasticity. We highlight the need to consider population differentiation in both mean traits and their plasticity to model realistic scenarios of species distribution under climate change.
Data from: Spatial heterogeneity in landscape structure influences dispersal and genetic structure: empirical evidence from a grasshopper in an agricultural landscape
Dispersal may be strongly influenced by landscape and habitat characteristics that could either enhance or restrict movements of organisms. Therefore, spatial heterogeneity in landscape structure could influence gene flow and the spatial structure of populations. In the past decades, agricultural intensification has led to the reduction in grassland surfaces, their fragmentation and intensification. As these changes are not homogeneously distributed in landscapes, they have resulted in spatial heterogeneity with generally less intensified hedged farmland areas remaining alongside streams and rivers. In this study, we assessed spatial pattern of abundance and population genetic structure of a flightless grasshopper species, Pezotettix giornae, based on the surveys of 363 grasslands in a 430-km² agricultural landscape of western France. Data were analysed using geostatistics and landscape genetics based on microsatellites markers and computer simulations. Results suggested that small-scale intense dispersal allows this species to survive in intensive agricultural landscapes. A complex spatial genetic structure related to landscape and habitat characteristics was also detected. Two P. giornae genetic clusters bisected by a linear hedged farmland were inferred from clustering analyses. This linear hedged farmland was characterized by high hedgerow and grassland density as well as higher grassland temporal stability that were suspected to slow down dispersal. Computer simulations demonstrated that a linear-shaped landscape feature limiting dispersal could be detected as a barrier to gene flow and generate the observed genetic pattern. This study illustrates the relevance of using computer simulations to test hypotheses in landscape genetics studies.
Data from: Designed habitat heterogeneity on green roofs increases seedling survival but not plant species diversity
Urban areas benefit from the ecosystem services provided by low input green roofs. However, limited substrate depth on these green roofs creates challenging conditions for plant establishment and survival, leading to industry reliance on non-native succulents. Through a green roof and glasshouse study, we assessed the impact of simple design modifications to the green roof surface, including redistribution of substrate and addition of logs and pebble piles, on both substrate temperature and moisture content. We added seeds of 26 native species and quantified seedling density, species richness and composition over a single growing season. Overall effects of microsite heterogeneity on species diversity were assessed using species accumulation curves. The modifications altered substrate temperature and moisture. Deep substrate (10-12 cm) and the presence of surface features reduced temperature by 14.6°C and, while surface features had mixed effects on substrate moisture on the green roof, pebble piles slowed moisture loss during a six-week drought in the glasshouse. Following drought conditions, seedling density and species richness was greatest, relative to seeded controls, where substrate was deep on the green roof and where pebbles were present in glasshouse modules, despite high mortality overall. Design modifications did not result in differentiation of seedling communities among different microsite types. Species accumulation curves showed no difference in species richness between aggregates of modified vs. unaltered microsites. Synthesis and applications. Redistribution of green roof substrate and the addition of logs and pebble piles altered microsite conditions and created habitat heterogeneity on a green roof. These design modifications represent a minimalist strategy to ameliorate growing conditions, improve seedling survival and decrease species loss on shallow substrate green roofs.
Supplemental Information: Dynamic Team Heterogeneity in Cooperative Coevolutionary Algorithms
<p>Videos of some of the solutions evolved with Hyb-CCEA and a standard CCEA, for the Soccer and Multi-rover tasks.</p>
Dataset from "Rewarded visual items capture attention only in heterogeneous contexts"
<p>Dataset from the following publication: Feldmann-Wüstefeld, T., Brandhofer, R. & Schubö, A. (2016). Rewarded visual items capture attention only in heterogeneous contexts. Psychophysiology, 53, 1063-1073. DOI: 10.1111/psyp.12641</p>
Heterogeneity of TRPV1 from EMPIAR 10059 studied 5 with different methods.
<p>Suplementary material for preprint publication</p> <p><br>https://www.biorxiv.org/content/10.1101/2024.10.07.617120v1</p>
Dataset: The Role and Lifetime of Dissociative Heterogeneous Processes in Improving Simulated Ozone on Mars
<p>VERSION 1:</p> <p>Dataset for the manuscript 'The Role and Lifetime of Dissociative Heterogeneous Processes in Improving Simulated Ozone on Mars'. The four netcdf files contain the full outputs to the MGCM for sols 7351-7381 (approximately Ls = 0 - 14, MY 35) with all chemical tracers:</p> <ul> <li>fullry_0_diagfi : 0% release dataset</li> <li>fullry_50_diagfi : 50% release dataset</li> <li>fullry_100_diagfi : 100% release dataset</li> <li>fullry_control_diagfi : control (gas only) dataset</li> </ul> <p>The MGCM values which match locations of observed ozone and water vapour TCA, as well as the observations themselves are found in df_nadir_gcm_vapo3_hyb_spin_20230829.pkl. </p> <p> </p> <p>VERSION 2:</p> <p>Also uploaded are the data for sols 7501-7531 (Ls = 68 - 82, MY 35):</p> <ul> <li>d7501-7531_control_diagfi : control (gas only) dataset</li> <li>d7501-7531_50_diagfi : 50% release dataset</li> </ul> <p> </p> <p>VERSION 3:</p> <p>Uploaded are data for sols 7621-7651 (Ls = 124 - 138, MY 35)</p> <ul> <li>d7621-7651_control_diagfi : control (gas only) dataset</li> <li>d7621-7651_50_diagfi : 50% release dataset</li> </ul> <p> </p>
Snow-Induced Perturbations in Nitrous Acid (HONO) Levels: Insights into Heterogeneous Reactions During Wintertime in Mid-Latitude Regions
<ol> <li>Variations in HONO, PM2.5, NO2, and HONO/NO2 concentrations data</li> <li>Time series data of pollutants</li> </ol>
Strong-ground motion for the city of Santiago (Chile) by using the Heterogeneous Energy-Based method
<p>Information pertaining to the generation of strong ground motion in the city of Santiago, Chile, using the Heterogeneous Energy-Based method proposed by Venegas-Aravena (2023) for the San Ramón Fault.</p>
Data from: Functional heterogeneity facilitates effectual collective task performance in a worker-polymorphic ant
<p class="MsoNormal"><span>Effective coordination of group actions underlies the success of group-living organisms. Recent studies of animal personality have shown that groups composed of individuals with different behavioral propensities can outperform uniform groups in a range of different tasks, but we have only a rudimentary understanding of how differences in individual behavior influence the behavior of the group as a whole. In this study, we use natural variation in behavioral propensity among morphologically distinct worker castes of the small carpenter ant <em>Camponotus yamaokai</em> to shed new light on this. Iterative testing indicated that ants displayed consistent behavioral differences among individuals and between castes, with major workers exhibiting a lower exploratory tendency than minors. By constructing groups of different caste composition and quantifying their performance in the task of colony emigration, we show that group performance is an asymmetric humped function of caste ratio, with optimal performance achieved by groups with natural caste ratios. Using a simulation model based on our empirical data, we demonstrate that inter-individual differences in social attraction and exploratory tendency are sufficient to explain the observed patterns. Our results provide new insights into how group performance in collective tasks can vary with group composition. </span></p>
Data from: geo-genomic predictors of genetree heterogeneity explain phylogeographic and introgression history: a case study in an Amazonian bird (Thamnophilus aethiops)
<p>Can knowledge about genome architecture inform biogeographic and phylogenetic inference? Selection, drift, recombination, and gene flow interact to produce a genomic landscape of divergence wherein patterns of differentiation and genealogy vary nonrandomly across the genomes of diverging populations. For instance, genealogical patterns that arise due to gene flow should be more likely to occur on smaller chromosomes, which experience high recombination, whereas those tracking histories of geographic isolation (reduced gene flow caused by a barrier) and divergence should be more likely to occur on larger and sex chromosomes. In Amazonia, populations of many bird species diverge and introgress across rivers, resulting in reticulated genomic signals. Herein, we used reduced representation genomic data to disentangle the biogeographic history of four populations of an Amazonian antbird, Thamnophilus aethiops, whose biogeographic history was associated with the dynamic evolution of the Madeira River Basin. Specifically, we evaluate whether a large river capture event ca. 200 kya, gave rise to reticulated genealogies in the genome by making spatially explicit predictions about isolation and gene flow based on knowledge about genomic processes. We first estimated chromosome-level phylogenies and recovered two primary topologies across the genome. The first topology (T1) was most consistent with predictions about population divergence, and was recovered for the Z chromosome. The second (T2), was consistent with predictions about gene flow upon secondary contact. To evaluate support for these topologies, we trained a convolutional neural network to classify our data into alternative diversification models and estimate demographic parameters. The best-fit model was concordant with T1 and included gene flow between non-sister taxa. Finally, we modeled levels of divergence and introgression as functions of chromosome length, and found that smaller chromosomes experienced higher gene flow. Given that (1) gene-trees supporting T2 were more likely to occur on smaller chromosomes and (2) we found lower levels of introgression on larger chromosomes (and especially the Z-chromosome), we argue that T1 represents the history of population divergence across rivers and T2 the history of secondary contact due to barrier loss. Our results suggest that a significant portion of genomic heterogeneity arises due to extrinsic biogeographic processes such as river capture interacting with intrinsic processes associated with genome architecture. Future biogeographic studies would benefit from accounting for genomic processes, as different parts of the genome reveal contrasting, albeit complementary histories, all of which are relevant for disentangling the intricate biogeographic mechanisms of biotic diversification.</p>
Fig. 3 in The Extent of Seed Predation by Bruchine Beetles (Coleoptera: Chrysomelidae: Bruchinae) in a Heterogeneous Landscape in Southeastern Brazil
Fig. 3. Cumulative percentage of germinated seeds (means ± SE) over an 11-day period for attacked and unattacked Leucaena leucocephala seeds. Germination was not recorded on days 2 and 5.
Fig. 1 in The Extent of Seed Predation by Bruchine Beetles (Coleoptera: Chrysomelidae: Bruchinae) in a Heterogeneous Landscape in Southeastern Brazil
Fig. 1. Monthly emergence of all bruchine species throughout the year of the study. Gibbobruchus spp., Acanthoscelides sp., Ctenocolum podagricus, and Acanthoscelides macrophthalmus emerged from seeds of Bauhinia forficata, Senna hirsuta, Lonchocarpus muehlbergianus, and Leucaena leucocephala, respectively. "Left" and "Right" in brackets mean that the emergence of each bruchine is recorded on the left or on the right y-axis.
Subset of instances used in article "On solving the 1.5-dimensional cutting stock problem with heterogeneous slitting lines allocation in the steel industry"
<p>The dataset presented is part of the one used in the article "On solving the 1.5-dimensional cutting stock problem with heterogeneous slitting lines allocation in the steel industry" by María Sierra-Paradinas, Óscar Soto-Sánchez, Antonio Alonso-Ayuso, F. Javier Martín-Campo and Micael Gallego, in Computers & Industrial Engineering (2024), doi: <a title="Persistent link using digital object identifier" href="https://doi.org/10.1016/j.cie.2024.110120" target="_blank" rel="noreferrer noopener"><span>https://doi.org/10.1016/j.cie.2024.110120</span></a>.</p> <p>This paper proposes a mathematical optimisation model for a cutting stock problem in the steel industry. This problem appears in a Spanish company and the proposed model has been tested on real orders received by the company.</p> <p>The dataset presented here includes twelve instances used in the paper (the rest cannot be presented for confidentiality reasons). For each instance, the characteristics of the order and the solution obtained by the model are provided.</p>
ScienceDex guides
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These curated guides explain access requirements, typical timelines, costs, and reuse considerations for widely used research datasets.
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.