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16,646 results for “four”
Data from: Above and belowground responses of four tundra plant functional types to deep soil heating and surface soil fertilization
1.Climate warming is faster in the Arctic than the global average. Nutrient availability in the tundra soil is expected to increase by climate warming through 1) accelerated nutrient mobilization in the surface soil layers, and 2) increased thawing depths during the growing season which increases accessibility of nutrients in the deeper soil layers. Both processes may initiate shifts in tundra vegetation composition. It is important to understand the effects of these two processes on tundra plant functional types. 2.We manipulated soil thawing depth and nutrient availability at a Northeast-Siberian tundra site to investigate their effects on above and belowground responses of four plant functional types (grasses, sedges, deciduous shrubs and evergreen shrubs). Seasonal thawing was accelerated with heating cables at ~15 cm depth without warming the surface soil, whereas nutrient availability was increased in the surface soil by adding slow-release NPK fertilizer at ~5 cm depth. A combination of these two treatments was also included. This is the first field experiment specifically investigating the effects of accelerated thawing in tundra ecosystems. 3.Deep soil heating increased the aboveground biomass of sedges, the deepest-rooted plant functional type in our study, but did not affect biomass of the other plant functional types. In contrast, fertilization increased aboveground biomass of the two dwarf shrub functional types, which both had very shallow root systems. Grasses showed the strongest response to fertilization, both above and belowground. Grasses were deep-rooted, and they showed the highest plasticity in terms of vertical root distribution, as grass root distribution shifted to deep and surface soil in response to deep soil heating and surface soil fertilization, respectively. 4.Synthesis - Our results indicate that increased thawing depth can only benefit deep-rooted sedges, while the shallow-rooted dwarf shrubs as well as flexible-rooted grasses take advantage of increased nutrient availability in the upper soil layers. Our results suggest that grasses have the highest root plasticity, which enables them to be more competitive in rapidly changing environments. We conclude that root vertical distribution strategies are important for vegetation responses to climate-induced increases in soil nutrient availability in Arctic tundra, and that future shifts in vegetation composition will depend on the balance between changes in thawing depth and nutrient availability in the surface soil.
Data from: Haplotype structure, adaptive history and associations with exploratory behaviour of the DRD4 gene region in four great tit (Parus major) populations
The assessment of genetic architecture and selection history in genes for behavioural traits is fundamental to our understanding of how these traits evolve. The dopamine receptor D4 (DRD4) gene is a prime candidate for explaining genetic variation in novelty seeking behaviour, a commonly assayed personality trait in animals. Previously we showed that a single nucleotide polymorphism in exon 3 of this gene is associated with exploratory behaviour in at least one of four Western European great tit (Parus major) populations. These heterogeneous association results were explained by potential variable linkage disequilibrium (LD) patterns between this marker and the causal variant or by other genetic or environmental differences among the populations. Different adaptive histories are further hypothesized to have contributed to these population differences. Here, we genotyped 98 polymorphisms of the complete DRD4 gene including the flanking regions for 595 individuals of the four populations. We show that the LD structure, specifically around the original exon 3 SNP is conserved across the four populations and does not explain the heterogeneous association results. Study-wide significant associations with exploratory behaviour were detected in more than one haplotype block around exon 2, 3 and 4 in two of the four tested populations with different allele effect models. This indicates genetic heterogeneity in the association between multiple DRD4 polymorphisms and exploratory behaviour across populations. The association signals were in or close to regions with signatures of positive selection. We therefore hypothesize that variation in exploratory and other dopamine-related behaviour evolves locally by occasional adaptive shifts in the frequency of underlying genetic variants.
Data from: Ontogenetic responses of four plant species to additive and interactive effects of land-use history, canopy structure and herbivory
The strength of interactions among species is often highly variable in space and time, and a major challenge in understanding context-dependent effects of herbivores lies in disentangling habitat-mediated from herbivore-mediated effects on plant performance. We conducted a landscape-scale experiment that manipulated light availability in woodlands with either a history of agricultural use or no history of agricultural use and coupled this with performance measurements of three life stages on four perennial herbaceous species exposed to varying levels of herbivory. We found that the context-dependent effects of herbivory on plant performance changed as plants grew: juvenile plant survival was reduced by herbivores in low-light habitats whereas biomass of adult plants was reduced by a more diverse insect fauna in high-light environments. A history of agricultural land use also had negative effects on seedling establishment and adult performance, independent of herbivory. Synthesis. This work experimentally separates the habitat-mediated effects on plant performance from the herbivore-mediated effects on plant performance and highlights how context-dependent interactions depend on plant ontogenetic stages.
Data from: Passerine extrapair mating dynamics: a Bayesian modeling approach comparing four species
In many socially monogamous animals, females engage in extrapair copulation (EPC), causing some broods to contain both within‐pair and extrapair young (EPY). The proportion of all young that are EPY varies across populations and species. Because an EPC that does not result in EPY leaves no forensic trace, this variation in the proportion of EPY reflects both variation in the tendency to engage in EPC and variation in the extrapair fertilization (EPF) process across populations and species. We analyzed data on the distribution of EPY in broods of four passerines (blue tit, great tit, collared flycatcher, and pied flycatcher), with 18,564 genotyped nestlings from 2,346 broods in two to nine populations per species. Our Bayesian modeling approach estimated the underlying probability function of EPC (assumed to be a Poisson function) and conditional binomial EPF probability. We used an information theoretical approach to show that the expected distribution of EPC per female varies across populations but that EPF probabilities vary on the above‐species level (tits vs. flycatchers). Hence, for these four passerines, our model suggests that the probability of an EPC mainly is determined by ecological (population‐specific) conditions, whereas EPF probabilities reflect processes that are fixed above the species level.
Data from: Adaptive genetic divergence along narrow environmental gradients in four stream insects
A central question linking ecology with evolutionary biology is how environmental heterogeneity can drive adaptive genetic divergence among populations. We examined adaptive divergence of four stream insects from six adjacent catchments in Japan by combining field measures of habitat and resource components with genome scans of non-neutral Amplified Fragment Length Polymorphism (AFLP) loci. Neutral genetic variation was used to measure gene flow and non-neutral genetic variation was used to test for adaptive divergence. We identified the environmental characteristics contributing to divergence by comparing genetic distances at non-neutral loci between sites with Euclidean distances for each of 15 environmental variables. Comparisons were made using partial Mantel tests to control for geographic distance. In all four species, we found strong evidence for non-neutral divergence along environmental gradients at between 6 and 21 loci per species. The relative contribution of these environmental variables to each species' ecological niche was quantified as the specialization index, S, based on ecological data. In each species, the variable most significantly correlated with genetic distance at non-neutral loci was the same variable along which each species was most narrowly distributed (i.e., highest S). These were gradients of elevation (two species), chlorophyll-a, and ammonia-nitrogen. This adaptive divergence occurred in the face of ongoing gene flow (Fst = 0.01–0.04), indicating that selection was strong enough to overcome homogenization at the landscape scale. Our results suggest that adaptive divergence is pronounced, occurs along different environmental gradients for different species, and may consistently occur along the narrowest components of species' niche.
Data from: Competitive responses of eight old-field plant species in four environments
Variation in relative competitive abilities among environments has been proposed to control the species composition of plant communities. We tested whether the competitive responses of eight species varied with fertility and disturbance in an old field. We also tested whether the competitive effects of vegetation varied with fertility and disturbance in an old field. We also tested whether the competitive effects of vegetation varied with fertility and disturbance. Plots received one of four combinations of nitrogen (added or not) and disturbance (tilled or not) in each of five years. There were 10 replicates of each treatment. In the fifth summer, transplants of eight species comprising annual and perennial forbs and grasses were grown in all four combinations of the N and disturbance treatments. Transplants were grown in subplots with all neighbors, with only roots of neighbors, or with no neighbors. Transplant roots and shoots were harvested after one summer and individual growth rates were determined. Growth rate varied significantly with the interaction among species, competition, and N, suggesting that species differed in their competitive responses and that these differences varied with N availability. Comparisons among competition treatments at each level of N showed six distinct responses in the eight species examined. The competitive effect of neighboring vegetation shifted from roots to shoots as N increased, but decreased in disturbed plots. The total effect of competition increased significantly with neighbor mass in 4 of the 32 examined (eight species in four combinations of N and disturbance). All four cases involved annuals in annual neighborhoods. The results for eight species confirmed earlier single—species diverged in their responses to competition as soil N availability varied.
The effect of inter-and intraspecific competition on individual and population niche widths – a four-decade study on two interacting salmonids
<p>Competition is assumed to shape niche widths, affecting species survival and coexistence. Expectedly, high interspecific competition will reduce population niche widths, whereas high intraspecific competition will do the opposite. Here we test in situ how intra- and interspecific competition affects trophic resource use and the individual and population niche widths of two lacustrine fish species, Arctic charr and brown trout, covering a 40 year study period with highly contrasting competitive impacts prior to and following a large-scale fish culling experiment. Initially, an overcrowded Arctic charr population dominated the study system, with brown trout being nearly absent. The culling experiment reduced the littoral Arctic charr density by 80%, whereupon brown trout gradually increased its density in the system. Thus, over the study period, the Arctic charr population went from high to low intraspecific competition, followed by increasing interspecific competition with brown trout. As hypothesized, the relaxed intraspecific competition following the experimental culling reduced individual diet specialization and compressed population niche width of Arctic charr. During the initial increase of the brown trout population, there was a large dietary overlap between the two species. Over the subsequent intensified interspecific competition from the population build-up of brown trout, their trophic niche overlap chiefly declined due to a dietary shift of Arctic charr towards enhanced zooplankton consumption. Contrary to theoretical expectations, the individual and population niche widths of Arctic charr increased with intensified interspecific competition. In contrast, the diet and niche width of brown trout remained stable over time, confirming its competitive superiority. The large-scale culling experiment and associated long-term research revealed pronounced temporal dynamics in trophic niche and resource use of the inferior competitor, substantiating that intra- and interspecific competition have large and contrasting impacts on individual and population niches.</p>
Data from: Comparative rangewide phylogeography of four endemic Taiwanese bat species
Phylogeographic reconstructions of co-distributed taxa can help reveal the interplay between abiotic factors, such as altitude and climate, and species-specific attributes, in shaping patterns of population genetic structure. Recent studies also demonstrate the value of both range-wide sampling and species distribution modeling (SDM) in comparative phylogeography. Here we combine these approaches to study the population histories of four phylogenetically-related forest-dependent bat species. All are endemic to the mountainous island of Taiwan but show differences in their tolerance to altitude, with Murina gracilis considered to be a high altitude specialist, M. recondita and Kerivoula sp. low altitude specialists, and M. puta an altitudinal generalist. We tested the prediction that contrasting habitat preferences would impact on patterns of past and contemporary gene flow, and found broad concordance between the results of population genetic analyses and MIROC-based species distribution models. Both lowland species showed evidence of genetic divergence between the east and west of the island, consistent with SDMs that indicated the Central Mountain Range (CMR) has presented a long-term and continuous barrier to gene flow since before the Last Glacial Maximum. In contrast, Murina gracilis and M. puta showed lower degrees of historical isolation and genetic differentiation associated with the CMR, reflecting greater gene flow, possibly coupled with past population growth in M. puta. Together our results highlight the usefulness of combining distribution models with phylogeographic analyses to understand the drivers of genetic structure.
Data from: Life history, growth, and reproductive biology of four mobulid species in the Bohol Sea, Philippines
This study focuses on female life-history parameters and reproductive cycles for four mobulid rays (Mobula thurstoni, Mo. japanica, Mo. tarapacana, and Manta birostris) caught in a targeted fishery in the Philippines. We collected size and reproductive data from 1,510 specimens (30% of catch) landed in two seasons in 2015 and 2016. Sexual maturity was assessed by visual examination of 1,034 specimens, to determine size-at-maturity and size-at-pregnancy. Females of all species matured at a larger size than males. Pregnancy ogives were estimated for all species except Mo. tarapacana, and shifted to the right of female maturity ogives, suggesting that only a small percentage of the female reproduce upon reaching sexual maturity. We report an aseasonal reproductive cycle at the population level for both Mo. thurstoni and Ma. birostris due to the absence of specific ovulation cycle and the wide size ranges of embryos examined throughout the months. The development of the follicles is not always synchronous with gestation, supporting the theory of a resting period between pregnancies. Our results show the low reproductive potential of these species and their conservative life history, and suggest that population growth rates previously reported are an overestimate.
Figure 6 in Mollusk distribution in four habitats along a salinity gradient in a coastal lagoon from the Gulf of Mexico
Figure 6. PCA plot showing relationships between environmental variables and molluscan assemblages from Mecoacan lagoon. Numbers represent sites, black dots = cold fronts season, open triangles = drought season, and black squares = rainy season. Sal: salinity; OD: dissolved oxygen; TDS: turbidity; Temp: temperature.
Figure 4 in Mollusk distribution in four habitats along a salinity gradient in a coastal lagoon from the Gulf of Mexico
Figure 4. MDS plot of bootstrap averages showing variations of molluscan assemblages by habitat. Ellipses denote approximate 95% confidence intervals and black symbols represent averages (av).
Figure 5 in Mollusk distribution in four habitats along a salinity gradient in a coastal lagoon from the Gulf of Mexico
Figure 5. MDS plot of bootstrap averages showing variations of molluscan assemblages by sites nested within a) ARE, b) MAN, c) VAS, and d) RAI. Ellipses denote approximate 95% confidence intervals and black symbols represent averages (av).
Figure 3 in Mollusk distribution in four habitats along a salinity gradient in a coastal lagoon from the Gulf of Mexico
Figure 3. MDS plot of bootstrap averages showing variation in molluscan assemblages by climatic season: cold fronts (triangles), drought (circles) and rainy (diamonds). Ellipses denote approximate 95% confidence intervals and black symbols represent averages (av).
Figure 2 in Mollusk distribution in four habitats along a salinity gradient in a coastal lagoon from the Gulf of Mexico
Figure 2. PCO showing the ordination of water environmental variables from Mecoacan lagoon. Numbers represent sites, black dots = cold fronts season, black squares = drought season, and black triangles = rainy season.
Fours # 3-4
Fours de bronzier, Palais Royal, Ankor Thom, Siem Reap, Cambodge Source: Objaverse 1.0 / Sketchfab
Bowl with receding rim & four buttons on the rim
Bowl with receding rim and four buttons on the rim. Argaric culture. Early-Middle Bronze Age (2300-1600 BC). Inventory number: PG.2807.1091 Find this object in the museum's online catalog [Carmentis](https://www.carmentis.be:443/eMP/eMuseumPlus?service=ExternalInterface&module=collection&objectId=133709&viewType=detailView) Source: Objaverse 1.0 / Sketchfab
The Four Saison
The Four saison, made at Louvain-la-neuve with Memento Beta Source: Objaverse 1.0 / Sketchfab
Four # 8
Fours de bronzier, Palais Royal, Ankor Thom, Siem Reap, Cambodge Source: Objaverse 1.0 / Sketchfab
Inrap - Fours de faïencerie - Rouen,Rue B.Pascal
Une équipe de l'Institut national de recherches archéologiques préventives (Inrap) est intervenue entre fin septembre 2019 et la mi-mai 2020, sur la rive gauche de la Seine à Rouen, à l'emplacement de l'ancien Centre de Formation des Apprentis (CFA Lanfry), dans le cadre d'un projet immobilier porté par le groupe Edouard Denis. Prescrite par les services de l'Etat (Drac Normandie), cette fouille permet d'étudier les vestiges d'une manufacture de faïence du XVIIIe siècle et de la filature qui lui a succédé au XIXe siècle. https://www.inrap.fr/des-installations-manufacturieres-et-industrielles-exhumees-rouen-14876 Traitement photogrammétrie - Sylvain Hérubel - Janvier 2020 Source: Objaverse 1.0 / Sketchfab
FIGURES 25–31 in Four new species of the genus Omaliopsis Jeannel, 1940 (Coleoptera: Staphylinidae: Omaliinae: Omaliini) of China
FIGURES 25–31. Omaliopsis obliquesignata: 25–aedeagus, parameral view, 26–aedeagus, lateral view, 27–male tergite VIII, 28–male sternite VIII, 29–female tergite VIII, 30–female sternite 8, 31–female accessory sclerite. Scale bar: 0.1 mm.
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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.