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655 results for “constrain”
Data from: Label-free timing analysis of SiPM-based modularized detectors with physics-constrained deep learning
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Limited migration from physiological refugia constrains the rescue of native gastropods facing an invasive predator
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There and back to the present: a model-based framework to estimate phylogenetically constrained alpha diversity gradients
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Sparsity-constrained wavefront optimization by leveraging complex media
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Predation risk constrains herbivores' adaptive capacity to warming
<p>Global warming compels larger endothermic animals to adapt either physiologically or behaviourally to avoid thermal stress, especially in tropical ecosystems. Their adaptive responses may however be compromised by other constraints, such as predation risk or starvation. Using an exceptional camera trap dataset spanning 32 protected areas across Southern Africa, we find that intermediate-sized herbivores (100-550kg) switch activity to hotter times of the day when exposed to predation by lions. These herbivores thus face a tight window for foraging activity being exposed to nocturnal predation and to heat during the day, suggesting a trade-off between predation risk and thermoregulation mediated by body size. These findings stress the importance of incorporating trophic interactions into climate change predictions.</p>
Irreversible habitat specialization does not constrain diversification in hypersaline water beetles
<p>Specialization to extreme environments is often considered an evolutionary dead-end, leading to irreversible adaptations and reduced evolvability. There is, however, mixed evidence of this macroevolutionary pattern, and limited data from speciose lineages. Here, we tested the effect of habitat specialization to hypersaline waters in the diversification rates of aquatic beetles of the genus <i><span>Ochthebius </span></i><span>(Coleoptera, Hydraenidae), using a molecular phylogeny with more than 50% of the 546 recognized species, including representatives of all subgenus and species groups but one. Phylogenies were built combining mitochondrial and nuclear genes, with the addition of 42 mitochondrial genomes. Using Bayesian methods of character reconstruction, we show that hypersaline tolerance is an irreversible ecological specialization that arose multiple times independently. Two lineages of </span><i><span>Ochthebius</span></i><span> experienced a significant increase in diversification rates, one of them inhabiting hypersaline waters, but there was no overall correlation with habitat or any significant decrease in diversification rates despite the irreversibility of the hypersaline tolerance.</span><span> Our study tested for the first time the impact of hypersaline habitat specialization on diversification rates, without support of being an evolutionary dead-end. On the contrary, multiple and ancient lineages fully adapted to these extreme osmotic conditions seem able to diversify over long evolutionary periods.</span></p>
Data set for 'Lunge filter feeding biomechanics constrain rorqual foraging ecology across scale'...
<p>Fundamental scaling relationships influence the physiology of vital rates, which in turn shape the ecology and evolution of organisms. For diving mammals, benefits conferred by large body size include reduced transport costs and enhanced breath-holding capacity, thereby increasing overall foraging efficiency. Rorqual whales feed by engulfing a large mass of prey-laden water at high speed and filter it through baleen plates. However, as engulfment capacity increases with body length across species (Engulfment Volume ∝ Body Length <sup>3.57</sup>), the surface area of the baleen filter does not increase proportionally (Baleen Area ∝ Body Length<sup>1.82</sup>), and thus the filtration time of larger rorquals predictably increases because the baleen surface area must filter a disproportionally large amount of water. We predicted that filtration time should scale with body length to the power of 1.75 (Filter Time ∝ Body Length<sup>1.75</sup><i>)</i>. We tested this hypothesis on four rorqual species using multi-sensor tags with corresponding unoccupied aerial systems (UAS) -based body length estimates. We found that filter time scales with body length to the power of 1.79 (95% CI: 1.61 - 1.97). This result highlights a scale-dependent trade-off between engulfment capacity and baleen area that creates a biomechanical constraint to foraging through increased filtration time. Consequently, larger whales must target high density prey patches commensurate to the gulp size to meet their increased energetic demands. If these optimal patches are absent, larger rorquals may experience reduced foraging efficiency compared to smaller whales if they do not match engulfment capacity to the size of targeted prey aggregations.</p>
Ancient crested penguin constrains timing of recruitment into seabird hotspot
<p>New Zealand is a globally significant hotspot for seabird diversity, but the sparse fossil record for most seabird lineages has impeded our understanding of how and when this hotspot developed. Here, we describe multiple exceptionally well-preserved specimens of a new species of penguin from tightly dated (3.36–3.06 Ma) Pliocene deposits in New Zealand. Bayesian and parsimony analyses place <i>Eudyptes atatu</i> sp. nov. as the sister species to all extant and recently extinct members of the crested penguin genus <i>Eudyptes</i>. The new species has a markedly more slender upper beak and mandible compared with other <i>Eudyptes</i> penguins. Our combined evidence approach reveals that deep bills evolved in both crested and stiff-tailed penguins (<i>Pygoscelis</i>) during the Pliocene. That deep bills arose so late in the greater than 60 million year evolutionary history of penguins suggests that dietary shifts may have occurred as wind-driven Pliocene upwelling radically restructured southern ocean ecosystems. Ancestral area reconstructions using BioGeoBEARS identify New Zealand as the most likely ancestral area for total-group penguins, crown penguins and crested penguins. Our analyses provide a timeframe for recruitment of crown penguins into the New Zealand avifauna, indicating this process began in the late Neogene and was completed via multiple waves of colonizing lineages.</p>
A non‐steady state model based on dual nitrogen and oxygen isotopes to constrain moss nitrate uptake and reduction
<p><span><span>Epilithic mosses are early colonizers of the terrestrial biosphere, constitute a special ecosystem regulating rock-atmosphere interactions, and may be more restricted in their nitrogen (N) supply than other mosses.<sup> </sup>Terrestrial mosses can take up nitrate (NO<sub>3</sub><sup>-</sup>), a major form of bioavailable N, from soil substrates. However, the importance of substrate NO<sub>3</sub><sup>-</sup> relative to atmospheric NO<sub>3</sub><sup>-</sup> remains unclear in moss NO<sub>3</sub><sup>-</sup> utilization. This has prevented the understanding of moss NO<sub>3</sub><sup>-</sup> dynamics and its responses to environmental N loadings. Here we investigated the monthly concentrations, δ<sup>15</sup>N, and δ<sup>18</sup>O of NO<sub>3</sub><sup>-</sup> in four epilithic moss species from August, 2006 to August, 2007 in Guiyang, southwestern China. We developed a non-steady state isotope mass-balance model based on dual N and O isotopes to evaluate fractional contributions of atmospheric NO<sub>3</sub><sup>-</sup> (<i>Ф</i><sub>atm</sub>) and soil NO<sub>3</sub><sup>-</sup> (<i>Ф</i><sub>soil</sub>), moss NO<sub>3</sub><sup>-</sup> uptake flux (<i>F</i><sub>influx</sub>), moss NO<sub>3</sub><sup>-</sup> reduction flux (<i>F</i><sub>reduction</sub>), and the percentage of NO<sub>3</sub><sup>-</sup> reduction in total NO<sub>3</sub><sup>-</sup> uptake of mosses (expressed as <i>f</i><sub>reduced</sub>). Monthly <i>Ф</i><sub>soil</sub> values averaged 53 ± 13% and monthly <i>f</i><sub>reduced</sub> values averaged 50 ± 35%. Both monthly<i> F</i><sub>reduction</sub> and <i>f</i><sub>reduced</sub> values increased with monthly <i>F</i><sub>influx</sub> values, particularly when <i>Ф</i><sub>soil</sub> values were higher than <i>Ф</i><sub>atm</sub> values. However, the amount of annual NO<sub>3</sub><sup>-</sup> reduction (219.7 ± 30.5 μg-N/g, dw) accounted for only 1.0 ± 0.2% in bulk N of mosses. We conclude that half of NO<sub>3</sub><sup>-</sup> in epilithic mosses is derived from soil NO<sub>3</sub><sup>-</sup> and that NO<sub>3</sub><sup>-</sup> uptake from soil induces moss NO<sub>3</sub><sup>-</sup> reduction, but the total NO<sub>3</sub><sup>-</sup> assimilation contributed a low fraction to total N of study mosses. These findings are important for understanding N sources and dynamics in terrestrial mosses.</span></span></p>
Data from: Constrained optimization of landscape indices in conservation planning to support ecological restoration in New Caledonia
<p>1. Curbing habitat loss, reducing fragmentation, and restoring connectivity are frequent concerns of conservation planning. In this respect, the incorporation of spatial constraints, fragmentation, and connectivity indices into optimization procedures is an important challenge for improving decision support.</p> <p>2. Here we present a novel optimization approach developed to accurately represent a broad range of conservation planning questions with spatial constraints and landscape indices. Relying on constraint programming, a technique from artificial intelligence based on automatic reasoning, this approach provides both constraint satisfaction and optimality guarantees.</p> <p>3. We applied this approach in a real case study to support managers of the ``Côte Oubliée -- `Woen Vùù -- Pwa Pereeù'' provincial park project, in the biodiversity hotspot of New Caledonia. Under budget, accessibility, and equitable allocation constraints, we identified restorable areas optimal for reducing forest fragmentation and improving inter-patch structural connectivity, respectively measured with the effective mesh size and the integral index of connectivity.</p> <p>4. Synthesis and applications. Our work contributes to more effective and policy-relevant conservation planning by providing a spatially-explicit and problem-focused optimization approach. By allowing an exact representation of spatial constraints and landscape indices, it can address new questions and ensure whether the solutions will be socio-economically feasible, through optimality and satisfiability guarantees. Our approach is generic and flexible, thus applicable to a wide range of conservation planning problems such as ecological restoration planning, reserve or corridor design.</p>
Dataset for: Trust Assessment in 32 KiB of RAM: Multi-application Trust-based Task Offloading for Resource-constrained IoT Nodes
<p>The dataset used to generate graphs for: Matthew Bradbury, Arshad Jhumka and Tim Watson. Trust Assessment in 32 KiB of RAM: Multi-application Trust-based Task Offloading for Resource-constrained IoT Nodes. Proceedings of the Symposium on Applied Computing, ACM, 2021, 1-10.</p> <p>Also includes instructions for experiment setup.</p> <p>Scripts from https://github.com/MBradbury/iot-trust-task-alloc are required to analyse and graph these results.</p>
Public Defense of Doctoral Thesis: "Improving the Resilience of the Constrained Internet of Things" (raw video)
<p>This is the raw video footage of Renzo E. Navas' public PhD Thesis Defense: "Improving the Resilience of the Constrained Internet of Things". Original date: Wednesday 9th of December 2020.</p>
Data from: Ecological and social factors constrain spatial and temporal opportunities for mating in a migratory songbird
Many studies of sexual selection assume that individuals have equal mating opportunities and that differences in mating success result from variation in sexual traits. However, the inability of sexual traits to explain variation in male mating success suggests that other factors moderate the strength of sexual selection. Extrapair paternity is common in vertebrates and can contribute to variation in mating success and thus serves as a model for understanding the operation of sexual selection. We developed a spatially explicit, multifactor model of all possible female-male pairings to test the hypothesis that ecological (food availability) and social (breeding density, breeding distance, and the social mate's nest stage) factors influence an individual's opportunity for extrapair paternity in a socially monogamous bird, the black-throated blue warbler, Setophaga caerulescens. A male's probability of siring extrapair young decreased with increasing distance to females, breeding density, and food availability. Males on food-poor territories were more likely to sire extrapair young, and these offspring were produced farther from the male's territory relative to males on food-abundant territories. Moreover, males sired extrapair young mostly during their social mates' incubation stage, especially males on food-abundant territories. This study demonstrates how ecological and social conditions constrain the spatial and temporal opportunities for extrapair paternity that affect variation in mating success and the strength of sexual selection in socially monogamous species.
Respiratory medium and circulatory anatomy constrain size evolution in marine macrofauna
<p>The typical marine animal has increased in biovolume by more than two orders of magnitude since the beginning of the Cambrian, but the causes of this trend remain unknown. We test the hypothesis that the efficiency of intra-organism oxygen delivery is a major constraint on body size evolution in marine animals. To test this hypothesis, we compiled a dataset comprising 13,723 marine animal genera spanning the Phanerozoic. We coded each genus according to its respiratory medium, circulatory anatomy, and feeding mode. In extant genera, we find that respiratory medium and circulatory anatomy explain more of the difference in size than feeding modes. Likewise, we find that most of the Phanerozoic increase in mean biovolume is accounted for by size increase in taxa that accomplish oxygen delivery through closed circulatory systems. During the Cambrian, water-breathing animals with closed circulatory systems were smaller, on average, than contemporaries with open circulatory systems. However, genera with closed circulatory systems superseded in size genera with open circulatory systems by the middle Ordovician, as part of their Phanerozoic-long trend of increasing size. In a regression analysis, respiratory and circulatory anatomy explain far more size variation in the living fauna than do feeding modes, even after accounting for taxonomic affinity at the class level. These findings suggest that ecological drivers of the Phanerozoic increase in the mean size of marine animals operated within strong, anatomically determined constraints.</p>
Data from: Does metabolism constrain bird and mammal ranges and predict shifts in response to climate change?
Mechanistic approaches for predicting the ranges of endotherms are needed to forecast their responses to environmental change. We test whether physiological constraints on maximum metabolic rate and the factor by which endotherms can elevate their metabolism (metabolic expansibility) influence cold range limits for mammal and bird species. We examine metabolic expansibility at the cold range boundary (MECRB) and whether species' traits can predict variability in MECRB and then use MECRB as an initial approach to project range shifts for 210 mammal and 61 bird species. We find evidence for metabolic constraints: the distributions of metabolic expansibility at the cold range boundary peak at similar values for birds (2.7) and mammals (3.2). The right skewed distributions suggest some species have adapted to elevate or evade metabolic constraints. Mammals exhibit greater skew than birds, consistent with their diverse thermoregulatory adaptations and behaviors. Mammal and bird species that are small and occupy low trophic levels exhibit high levels of MECRB. Mammals with high MECRB tend to hibernate or use torpor. Predicted metabolic rates at the cold range boundaries represent large energetic expenditures (>50% of maximum metabolic rates). We project species to shift their cold range boundaries poleward by an average of 3.9° latitude by 2070 if metabolic constraints remain constant. Our analysis suggests that metabolic constraints provide a viable mechanism for initial projections of the cold range boundaries for endotherms. However, errors and approximations in estimating metabolic constraints (e.g., acclimation responses) and evasion of these constraints (e.g., torpor/hibernation, microclimate selection) highlight the need for more detailed, taxa‐specific mechanistic models. Even coarse considerations of metabolism will likely lead to improved predictions over exclusively considering thermal tolerance for endotherms.
A lack of genetically compatible mates constrains the spread of an invasive weed
<ul> <li>Introduced populations often experience lag-times prior to invasion, but the mechanisms constraining rapid expansions of introduced populations are unclear. <i>Solidago altissima</i> is a North American native plant with highly invasive Japanese populations, and introduced Australian populations that are not invasive despite the climatic and ecological suitability of the region.</li> <li>By contrasting Australian with Japanese populations, we tested the hypothesis that Australian population growth is limited by a lack of long-distance dispersal via seeds due to limited number of compatible mates. </li> <li>In the field, Australian populations rarely produced viable seeds. A cross-pollination experiment found that Australian plants are fertile, yet lack compatible mates within Australia. Genetic analysis revealed that Australian individuals descend from a small set of self-incompatible genetic clones, which explains the negligible seed set within Australia.</li> <li>Our results show that low genetic diversity, leading to mate incompatibility, inhibits invasiveness of Australian <i>S. altissima</i>, and provides compelling evidence for genetic, rather than ecological, factors constraining invasion in Australia.</li> </ul>
Data from: Running in circles in phylomorphospace: host environment constrains morphological diversification in parasitic wasps
Understanding phenotypic diversification and the conditions that spur morphological novelty or constraint is a major theme in evolutionary biology. Unequal morphological diversity between sister clades can result from either differences in the rate of morphological change or in the ability of clades to explore novel phenotype ranges. We combine an existing phylogenetic framework with new phylogenomic data and geometric morphometrics to explore the relative roles of rate versus mode of morphological evolution for a hyperdiverse group: cryptine ichneumonid wasps. Data from genomic ultraconserved elements (UCEs) confirm that cryptines are divided into two large clades: one specialized in the use of hosts that are deeply concealed under hard substrates, and another with a much more diversified host range. Using a phylomorphospace approach, we show that both clades have experienced similar rates of morphological evolution. Nonetheless, the more specialized group is much more restricted in morphospace occupation, indicating that it repeatedly evolved morphological change through the same morphospace regions. This is in agreement with our prediction that host use imposes constraints in the morphospace available to lineages, and reinforces an important distinction between evolutionary stasis as opposed to a scenario of continual morphological change restricted to a certain range of morphotypes.
Data from: The Bogert effect revisited: salamander regulatory behaviors are differently constrained by time and space
The use of behavior to buffer extreme environmental variation is expected to enable species to a) extend the breadth of environments they inhabit beyond that predicted from climatic data, and b) diminish the negative effects of broad-scale and chronic disturbances such as climate change. The term Bogert effect refers to behavioral compensation entailing microhabitat selection to maintain performance across a gradient of environmental conditions resulting in evolutionary inertia of physiological traits. Here we compare microhabitats used by plethodontid salamanders distributed along an elevational gradient to determine whether there is behavioral compensation that buffers them from deleterious temperatures and moisture levels. Overall, salamanders preferred cooler and more mesic environments and occupied microhabitats that maintained constant moisture conditions at both high and low elevation sites. Our results suggest that salamanders use microhabitats to regulate temperature and moisture levels, which is consistent with the Bogert effect. Maintenance of more moist conditions may help buffer these species from rising temperatures, but only in suitable high-elevation environments that are likely to disappear over the next century. We conclude that behavioral regulation of temperature and moisture is a potential mechanism for the Bogert effect in plethodontid salamanders.
Data from: Accounting for disturbance history in models: using remote sensing to constrain carbon and nitrogen pool spin‐up
Disturbances such as wildfire, insect outbreaks, and forest clearing, play an important role in regulating carbon, nitrogen, and hydrologic fluxes in terrestrial watersheds. Evaluating how watersheds respond to disturbance requires understanding mechanisms that interact over multiple spatial and temporal scales. Simulation modeling is a powerful tool for bridging these scales; however, model projections are limited by uncertainties in the initial state of plant carbon and nitrogen stores. Watershed models typically use one of two methods to initialize these stores: spin-up to steady state, or remote sensing with allometric relationships. Spin-up involves running a model until vegetation reaches equilibrium based on climate; this approach assumes that vegetation across the watershed has reached maturity and is of uniform age, which fails to account for landscape heterogeneity and non-steady state conditions. By contrast, remote sensing, can provide data for initializing such conditions. However, methods for assimilating remote sensing into model simulations can also be problematic. They often rely on empirical allometric relationships between a single vegetation variable and modeled carbon and nitrogen stores. Because allometric relationships are species- and region-specific, they do not account for the effects of local resource limitation, which can influence carbon allocation (to leaves, stems, roots, etc.). To address this problem, we developed a new initialization approach using the catchment-scale ecohydrologic model RHESSys. The new approach merges the mechanistic stability of spin-up with the spatial fidelity of remote sensing. It uses remote sensing to define spatially explicit targets for one, or several vegetation state variables, such as leaf area index, across a watershed. The model then simulates the growth of carbon and nitrogen stores until the defined targets are met for all locations. We evaluated this approach in a mixed pine-dominated watershed in central Idaho, and a chaparral-dominated watershed in southern California. In the pine-dominated watershed, model estimates of carbon, nitrogen, and water fluxes varied among methods, while the target-driven method increased correspondence between observed and modeled streamflow. In the chaparral watershed, where vegetation was more homogeneously aged, there were no major differences among methods. Thus, in heterogeneous, disturbance-prone watersheds, the target-driven approach shows potential for improving biogeochemical projections.
The Dynamics of the India-Eurasia Collision: Faulted Viscous Continuum Models Constrained by High-Resolution Sentinel-1 InSAR and GNSS Velocities
<p>Velocity field for the India-Eurasia collision zone from Sentinel-1 InSAR and GNSS data</p> <p>Citations:</p> <p>[1] Jin Fang, Gregory A Houseman, Tim J Wright, Lynn A Evans, Tim J Craig, John R Elliott and Andy Hooper (2023). The Dynamics of the India-Eurasia Collision: Faulted Viscous Continuum Models Constrained by High-Resolution Sentinel-1 InSAR and GNSS Velocities [Dataset]. Zenodo. https://doi.org/10.5281/zenodo.10053499</p> <p>[2] Jin Fang, Gregory A Houseman, Tim J Wright, Lynn A Evans, Tim J Craig, John R Elliott and Andy Hooper (2024). The Dynamics of the India-Eurasia Collision: Faulted Viscous Continuum Models Constrained by High-Resolution Sentinel-1 InSAR and GNSS Velocities, Journal of Geophysical Research: Solid Earth, https://doi.org/10.1029/2023JB028571</p> <p>More details about the methodology to generate the velocity field can be found in Wright et al. (2023):</p> <p>[3] Tim J Wright, Greg Houseman, Jin Fang, Yasser Maghsoudi, Andy Hooper, John Elliott, Lynn Evans, Milan Lazecky, Qi Ou, Barry Parsons, Chris Rollins, Lin Shen, Hua Wang (2023). High-resolution geodetic strain rate field reveals dynamics of the India-Eurasia collision, submitted to Science, preprint available at https://doi.org/10.31223/X5G95R.</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.