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718 results for “Crown”
Walnut Gulch Experimental Watershed site, station Shrubs with grass vegetation zone in Walnut Gulch Watershed, study of plant cover of Koeberlinia spinosa (crown of thorns) in units of percent on a yearly timescale
The EcoTrends project was established in 2004 by Dr. Debra Peters (Jornada Basin LTER, USDA-ARS Jornada Experimental Range) and Dr. Ariel Lugo (Luquillo LTER, USDA-FS Luquillo Experimental Forest) to support the collection and analysis of long-term ecological datasets. The project is a large synthesis effort focused on improving the accessibility and use of long-term data. At present, there are ~50 state and federally funded research sites that are participating and contributing to the EcoTrends project, including all 26 Long-Term Ecological Research (LTER) sites and sites funded by the USDA Agriculture Research Service (ARS), USDA Forest Service, US Department of Energy, US Geological Survey (USGS) and numerous universities. Data from the EcoTrends project are available through an exploratory web portal (http://www.ecotrends.info). This web portal enables the continuation of data compilation and accessibility by users through an interactive web application. Ongoing data compilation is updated through both manual and automatic processing as part of the LTER Provenance Aware Synthesis Tracking Architecture (PASTA). The web portal is a collaboration between the Jornada LTER and the LTER Network Office. The following dataset from Walnut Gulch Experimental Watershed (WGE) contains plant cover of Koeberlinia spinosa (crown of thorns) measurements in percent units and were aggregated to a yearly timescale.
Extended Data Fig. 6 in Late Cretaceous neornithine from Europe illuminates the origins of crown birds
Extended Data Fig. 6 | Postcranial morphology of A. maastrichtensis (NHMM 2013 008). The left distal femur of Presbyornis pervetus (UW 27596) is shown for comparison.
Extended Data Fig. 3 in Late Cretaceous neornithine from Europe illuminates the origins of crown birds
Extended Data Fig. 3 | Morphology of individually segmented skull elements from A. maastrichtensis (NHMM 2013 008). Dorsal,ventral and rostral views of the frontals show the nasals separated from their in situ position to illustrate the morphology of the nasofrontal contact.Scale bars,1 cm.
Fig. 3 in Late Cretaceous neornithine from Europe illuminates the origins of crown birds
Fig. 3 | Relationships of A. maastrichtensis and stratigraphic provenance of holotype. a, Cladogram showing the phylogenetic position of Asteriornis and Vegavis inferred under parsimony (solid coloured lines) and tip-dated Bayesian analyses (dashed lines).A position for Vegavis allied with Anseriformes,as previously found12,28,34, is also shown (curved branch).Numbers within clades denote extant species richness.The analysis is based on a newly modified dataset;see Extended Data Fig. 9 and Supplementary Information for full phylogenetic results.Extinct taxa are denoted with daggers.b, Simplified stratigraphy of the Maastricht Formation,exposed in the vicinity of the holotype locality and surrounding areas24. c, Location of the CBR-Romontbos Quarry near Eben-Emael,Belgium.
FIGURE 9 in Species limits in the Tawny-crowned Pygmy-tyrant Euscarthmus meloryphus complex (Aves: Passeriformes: Tyrannidae)
FIGURE 9. Species Distribution Modeling of populations identified as Euscarthmus meloryphus paulus for the present (top) and the Last Glacial Maximum (21 kyr BP; bottom). Training AUC = 0.9706, test AUC = 0.9376. Occurrence points are presented as white circles.
FIGURE 7 in Species limits in the Tawny-crowned Pygmy-tyrant Euscarthmus meloryphus complex (Aves: Passeriformes: Tyrannidae)
FIGURE 7. Principal Component Analysis of 19 variables of the loudsongs of Euscarthmus m. meloryphus (orange circles), E. meloryphus paulus (yellow circles), and E. meloryphus fulviceps (red circles). Cumulative proportion of the total variance explained by principal component 1 (pace, overall number of notes, duration of interval between last and penultimate introductory notes) and principal component 2 (overall minimum frequency, minimum frequency of the last introductory note) are in parentheses beside axis labels.
The Fungal Endophyte Epichloë festucae var. lolii Plays a Limited Role in Mediating Crown Rust Severity in Perennial Ryegrass
<p>Perennial ryegrass (Lolium perenne L.) is an important turf and forage species that often becomes infected with Puccinia coronata f. sp. lolii, the causal pathogen of crown rust. Disease control through clavicipitaceous endophytes has been proposed as a potential biocontrol. Two field experiments were designed to determine the influence of native Epichloë endophyte infection on natural rust development across a diverse panel of perennial ryegrass germplasm. Experiment 1 used an isogenic population design in which infected (E+) or endophyte-free (E−) clonal plants were nested within 14 perennial ryegrass entries. Experiment 2 consisted of isofrequent E+ and E− progeny from isogenic parents. Results showed the endophyte had no consistent main effect on crown rust severity across or within entries; however, several isogenic host pairs did show either favorable or antagonistic effects. Despite these sporadic effects, no differences were found between isofrequent family pairs, indicating the presence of a host endophyte interaction. Genotypic and phenotypic data revealed that endophyte isolates were similar within entry, indicating that host genotype could be responsible for the highly specific endophyte effect on crown rust. The preponderance of host resistance in mediating rust severity was supported by large broad (>.75) and narrow-sense (.76) heritability estimates. These findings support the conclusion that endophyte infection does not play a substantial role in mediating crown rust severity on a population scale in perennial ryegrass.</p>
Data from: Inner ear morphology of diadectomorphs and seymouriamorphs (Tetrapoda) uncovered by high-resolution x-ray microcomputed tomography, and the origin of the amniote crown group
The origin of amniotes was a key event in vertebrate evolution, enabling tetrapods to break their ties with water and invade terrestrial environments. Two pivotal clades of early tetrapods, the diadectomorphs and the seymouriamorphs, have played an unsurpassed role in debates about the ancestry of amniotes for over a century, but their skeletal morphology has provided conflicting evidence for their affinities. Using high-resolution X-ray microcomputed tomography, we reveal the three-dimensional architecture of the well preserved endosseous labyrinth of the inner ear in representative species belonging to both groups. Data from the inner ear are coded in a new cladistic matrix of stem and primitive crown amniotes. Both maximum parsimony and Bayesian inference analyses retrieve seymouriamorphs as derived non-crown amniotes and diadectomorphs as sister group to synapsids. If confirmed, this sister group relationship invites re-examination of character polarity near the roots of the crown amniote radiation. Major changes in the endosseous labyrinth and adjacent braincase regions are mapped across the transition from non-amniote to amniote tetrapods, and include: a ventral shift of the cochlear recess relative to the vestibule and the semicircular canals; cochlear recess (primitively housed exclusively within the opisthotic) accommodated within both the prootic and the opisthotic; development of a distinct fossa subarcuata. The inner ear of seymouriamorphs foreshadows conditions of more derived groups, whereas that of diadectomorphs shows a mosaic of plesiomorphic and apomorphic traits, some of which are unambiguously amniote-like, including a distinct and pyramid-like cochlear recess.
Limited evidence of cloning and selfing within wild populations of coral-eating crown-of thorns seastar (Acanthaster cf. solaris)
<p>Population outbreaks of crown-of-thorns seastars (CoTS; <i>Acanthaster</i> spp.) are contributing to extensive coral loss and reef degradation throughout the Indo west-Pacific, but the causes and underlying mechanisms of population maintenance and outbreaks are equivocal. Two recent publications suggest that, in addition to outbreeding sexual reproduction, asexual reproduction through larval fission and selfing may contribute to rapid increases in the local abundance of <i>Acanthaster</i> spp. We re-analysed two large microsatellite datasets (collectively representing 3,714 individuals) that investigated connectivity in the Great Barrier Reef and Pacific region to investigate if potential cloning or selfing can be evidenced in the population genetic structure. Within this dataset we identified only a small number (18, < 0.5%) of putative clones (repeated multi locus genotypes). We argue that several of these are due to sampling and processing errors rather than direct evidence of cloning. Analysis of the population genetic structure (i.e., pairwise genetic differences between individuals, deviations from Hardy-Weinberg-Equilibrium, and linkage disequilibrium) also yielded no genetic evidence for asexual reproduction. There was a tendency towards slight heterozygote deficits, so we cannot refute that selfing does occur, but this is mostly likely attributable to sampling artefacts. Although we cannot exclude that asexual reproduction occurs to some extent in <i>Acanthaster</i> populations, we find no evidence that these processes make <span>a</span> contribution to population structure or directly enhance larval supply.</p>
Supporting Data: Monitoring spring phenology of individual tree crowns using drone-acquired NDVI data
<p>This data supports the RSEC publication: "Monitoring spring phenology of individual tree crowns using drone-acquired NDVI data"</p> <p>GeoTIFF:</p> <p>NDVI and green band orthomosaics from data acquired using a Parrot Sequoia camera mounted on a 3DR Solo quadcopter drone. Filename indicates data capture date (YYYY-MM-DD).</p> <p>Shapefiles:</p> <p>Shapefiles with tree ROIs and corresponding species class, described in ReadMe file.</p>
Data from: Closing a gap in tropical forest biomass estimation: taking crown mass variation into account in pantropical allometries
Accurately monitoring tropical forest carbon stocks is an outstanding challenge. Allometric models that consider tree diameter, height and wood density as predictors are currently used in most tropical forest carbon studies. In particular, a pantropical biomass model has been widely used for approximately a decade, and its most recent version will certainly constitute a reference in the coming years. However, this reference model shows a systematic bias for the largest trees. Because large trees are key drivers of forest carbon stocks and dynamics, understanding the origin and the consequences of this bias is of utmost concern. In this study, we compiled a unique tree mass dataset on 673 trees measured in five tropical countries (101 trees > 100 cm in diameter) and an original dataset of 130 forest plots (1 ha) from central Africa to quantify the error of biomass allometric models at the individual and plot levels when explicitly accounting or not accounting for crown mass variations. We first showed that the proportion of crown to total tree aboveground biomass is highly variable among trees, ranging from 3 to 88 %. This proportion was constant on average for trees < 10 Mg (mean of 34 %) but, above this threshold, increased sharply with tree mass and exceeded 50 % on average for trees ≥ 45 Mg. This increase coincided with a progressive deviation between the pantropical biomass model estimations and actual tree mass. Accounting for a crown mass proxy in a newly developed model consistently removed the bias observed for large trees (> 1 Mg) and reduced the range of plot-level error from −23–16 to 0–10 %. The disproportionally higher allocation of large trees to crown mass may thus explain the bias observed recently in the reference pantropical model. This bias leads to far-from-negligible, but often overlooked, systematic errors at the plot level and may be easily corrected by accounting for a crown mass proxy for the largest trees in a stand, thus suggesting that the accuracy of forest carbon estimates can be significantly improved at a minimal cost.
Data from: Crown asymmetry in high latitude forests: disentangling the directional effects of tree competition and solar radiation
Light foraging by trees is a fundamental process shaping forest communities. In heterogeneous light environments this behavior is expressed as plasticity of tree growth and the development of structural asymmetries. We studied the relative influence of neighborhood structure and directional solar radiation on horizontal asymmetry of tree crowns in late-successional high latitude (67–68°N) forests in northern Fennoscandia. We described crown asymmetries as crown vectors (i.e. horizontal vectors from stem center to crown center), which we obtained from canopy maps based on crown perimeter measurements in the field. To disentangle the influence of the two main determinants, inter-tree competition and directionality of above-canopy solar radiation at high latitudes, we applied circular statistical models, utilizing cylindrical distributions, to these data consisting of orientations and intensities of crown asymmetry. At the individual tree level, our model predicted crown asymmetry vectors from the current stand structure, and the predictions became better when the intensity of asymmetry (i.e. crown vector length) was higher. Competition was the main determinant of crown asymmetry for 2/3 of trees, and the model predictions improved when we incorporated the directionality of solar radiation. At the stand-level, these asymmetries had resulted in a small increment of the projected canopy area and an increased regularity of spatial structure. Our circular statistical modelling approach provided a quantitative evaluation of the relative importance of directionality of solar radiation and neighborhood stand structure, showing how both of these factors play a role in formation of crown asymmetries in high latitude forests. This approach further demonstrated the applicability of circular statistical modeling in ecological studies where the response variable has both orientation and intensity.
Data from: Neighbour species richness and local structural variability modulate aboveground allocation patterns and crown morphology of individual trees
<p>Local neighbourhood interactions are considered a main driver for biodiversity–productivity relationships in forests. Yet, the structural responses of individual trees in species mixtures and their relation to crown complementarity remain poorly understood. Using a large‐scale forest experiment, we studied the impact of local tree species richness and structural variability on above‐ground wood volume allocation patterns and crown morphology. We applied terrestrial laser scanning to capture the three‐dimensional structure of trees and their temporal dynamics. We found that crown complementarity and crown plasticity increased with species richness. Trees growing in species‐rich neighbourhoods showed enhanced aboveground wood volume both in trunks and branches. Over time, neighbourhood diversity induced shifts in wood volume allocation in favour of branches, in particular for morphologically flexible species. Our results demonstrate that diversity‐mediated shifts in allocation pattern and crown morphology are a fundamental mechanism for crown complementarity and may be an important driver of overyielding.</p> <p> </p>
Data from: Role of axis reversal from the short-shoot to long-shoot habit for crown maintenance in slow-growing Betula maximowicziana trees
PREMISE OF THE STUDY: Branch growth and its spatial arrangement determine tree crown architecture and leaf display, and thus the productivity of trees. Branch axes elongate by the sequential production of shoots with differing morphology and function, such as short shoots and long shoots. This study investigated ontogenetic changes in axis growth in Betula maximowicziana and quantified the role of axis reversal between the short-shoot and long-shoot habit, particularly reversal from the short-shoot to long-shoot habit. METHODS: From eight trees with varying levels of growth vigor, 716 branch axes forming the basic crown architecture were sampled. Past growth of the branch axes was reconstructed from leaf and bud scale scars, and compared between slow-growing and vigorously growing trees. KEY RESULTS: Branch axes reversed more frequently between the long- and short-shoot habits in slow-growing trees than in vigorously growing trees. Short-shoot-origin axes that reversed to the long-shoot habit lived for longer periods and grew larger than axes that remained in the short-shoot habit. Short-shoot-origin axes reversed as they grew away from branch apices, typically more than 6 years after they had originated. CONCLUSIONS: Reversal of short-shoot-origin axes to the long-shoot habit is an endogenous growth process of trees with reduced vigor. Like epicormic branching, the reversal may contribute to the maintenance of productivity of large old trees by prolonging axis longevity and filling the inner part of the crown. This study presented an ontogenetic change in branch growth, which broadened our perspectives on the growth and survival of long-living trees.
Data from: Mosaicism in a new Eocene pufferfish highlights rapid morphological innovation near the origin of crown tetraodontiforms
Tetraodontiformes (pufferfishes and kin) is a taxonomically and structurally diverse, widely-distributed clade of acanthomorphs, whose members often serve as models for genomics and, increasingly, macroevolutionary studies. Morphologically disparate Palaeogene fossils suggest considerable early experimentation, but these flattened specimens often preserve limited information. We present a three-dimensionally preserved beaked tetraodontiform from the early Eocene (c. 53 Ma) London Clay Formation, UK. Approximately coeval with the oldest crown tetraodontiforms, †Ctenoplectus williamsi gen. et sp. nov. presents an unprecedented combination of characters, pairing a fused beak-like dentition with prominent dorsal-fin spines that insert atop transversely-expanded pterygiophores roofing the skull. Bayesian total-evidence tip-dating analysis indicates that †Ctenoplectus represents the sister lineage of Triodontidae and highlights considerable levels of homoplasy in early tetraodontiform evolution. According to our dataset, rates of morphological character evolution were elevated at the origin of crown Tetraodontiformes, especially within gymnodonts, but declined after the principal body plans were established. Such 'early burst' patterns are regarded as a hallmark of adaptive radiations, but are typically associated with diversification at smaller spatiotemporal scales. However, denser sampling of Neogene and Recent taxa is needed to confirm this pattern.
Data from: Bias associated with the detectability of the coral-eating pest crown-of-thorns seastar and implications for reef management
Outbreaks of the predator crown-of-thorns seastar (COTS) Acanthaster planci cause widespread coral mortality across the Indo-Pacific. Like many marine invertebrates, COTS is a nocturnal species whose cryptic behaviour during the day can affect its detectability, particularly in structurally complex reef habitats that provide many refuges for benthic creatures. We performed extensive day and night surveys of COTS populations in coral reef habitats showing differing levels of structural complexity and COTS abundance. We tested whether estimations of COTS density varied between day and night observations, and if the differences were related to changes in COTS abundance, reef structural complexity, and the spatial scale of observation. Estimations of COTS density were on average 27% higher at night than during the day. Differences in COTS detection varied with changing seastar abundance but not reef structural complexity or scale of observation. Underestimation of COTS abundance in daytime was significant for a broad seastar density range, thus potentially affecting most outbreak events. Our study suggests that portions of COTS populations can be undetected during conventional surveys and control campaigns, which are exclusively conducted by day, and significantly affect the trajectory of coral reefs. Accounting for bias in COTS detection can strengthen coral reef management broadly.
Data from: Tropical tree height and crown allometries for the Barro Colorado Nature Monument, Panama: a comparison of alternative hierarchical models incorporating interspecific variation in relation to life history traits
Tree allometric relationships are widely employed for estimating forest biomass and production and are basic building blocks of dynamic vegetation models. In tropical forests, allometric relationships are often modeled by fitting scale-invariant power functions to pooled data from multiple species, an approach that fails to capture changes in scaling during ontogeny and physical limits to maximum tree size and that ignores interspecific differences in allometry. Here, we analyzed allometric relationships of tree height (9884 individuals) and crown area (2425) with trunk diameter for 162 species from the Barro Colorado Nature Monument, Panama. We fit nonlinear, hierarchical models informed by species traits – wood density, mean sapling growth, or sapling mortality – and assessed the performance of three alternative functional forms: the scale-invariant power function and the saturating Weibull and generalized Michaelis–Menten (gMM) functions. The relationship of tree height with trunk diameter was best fit by a saturating gMM model in which variation in allometric parameters was related to interspecific differences in sapling growth rates, a measure of regeneration light demand. Light-demanding species attained taller heights at comparatively smaller diameters as juveniles and had shorter asymptotic heights at larger diameters as adults. The relationship of crown area with trunk diameter was best fit by a power function model incorporating a weak positive relationship between crown area and species-specific wood density. The use of saturating functional forms and the incorporation of functional traits in tree allometric models is a promising approach for improving estimates of forest biomass and productivity. Our results provide an improved basis for parameterizing tropical plant functional types in vegetation models.
A comparison of neutral genetic differentiation and genetic diversity among migratory and resident populations of Golden-crowned-Kinglets (Regulus satrapa)
<p>Many animals migrate seasonally between breeding and non-breeding territories and these annual movements can have a profound effect on population genetic structure. We genotyped 283 individuals from 11 populations at seven variable microsatellite loci and compared patterns of neutral genetic differentiation and neutral genetic diversity among migratory and resident breeding populations of the Golden-crowned Kinglet (Regulus satrapa), a widespread North American songbird. We predicted that resident populations would exhibit greater genetic differentiation and lower genetic diversity than migratory populations because migratory behaviour is thought to enhance gene flow. The magnitude of genetic differentiation and genetic diversity among migratory and resident populations was comparable, and the greatest levels of differentiation were observed for pairwise comparisons between Ontario and all western populations. Distance-based redundancy models and redundancy models revealed that patterns of neutral genetic differentiation and neutral genetic diversity follow an isolation-by-distance model and are not correlated with migratory behaviour. Overall it appears that genetic patterns are more closely associated with Pleistocene glacial history as proposed in a previous study.</p>
Oliver Cromwell's silver crown (1658).
Oliver Cromwell's silver crown (1658). Year of minting: 1658. Inscription: "Oliver, by God's grace protector of the Republic of England, Scotland and Ireland". Oliver Cromwell - the leader of the English Revolution, an outstanding military leader and statesman, in the years 1643-1650. - Lieutenant General of the Parliamentary Army, in 1650-1653. - Lord General, in 1653-1658. - Lord Protector of England, Scotland and Ireland. It is believed that his death came from malaria or from poisoning. After his death, his body was removed from the grave, hanged and quartered, which was the traditional punishment for treason in England. Серебряная крона Оливера Кромвеля. Год чеканки: 1658. Надпись: «Оливер, Божьей милостью защитник республики Англии, Шотландии и Ирландии». Оливер Кромвель — вождь Английской революции, выдающийся военачальник и государственный деятель, в 1643—1650 гг. — генерал-лейтенант парламентской армии, в 1650—1653 гг. — лорд-генерал, в 1653—1658 гг. — лорд-протектор Англии, Шотландии и Ирландии. Source: Objaverse 1.0 / Sketchfab
Barrera Cemento Crown Plaza Dec19
Barrera Cemento Crown Plaza Dec19 Source: Objaverse 1.0 / Sketchfab
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Allen Brain Atlas
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DANDI Archive for NWB datasets
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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.