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1,610 results for “ratio”
Adult sex-ratio bias does not lead to detectable adaptive offspring sex allocation via nest-site choice in a turtle with temperature-dependent sex determination
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Range-wide study in a sexually polymorphic wild strawberry reveals climatic and soil associations of sex ratio, sexual dimorphism, and sex chromosomes
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Coastal Wetland Basal Consumer and End Member C-13 and N-15 Isotopic Ratios Across a Mangrove Encroachment Gradient, 2019
Foundation species support highly productive and valuable ecosystems, but anthropogenic disturbances and environmental changes are increasingly causing foundation species shifts, where one foundation species replaces another. The consequences of foundation shifts are not well understood, as there is limited research on the equivalency of different foundation species and the functions they support. Here, we provide insight into community-level consequences of foundation shifts in the Gulf of Mexico, where the typical marsh foundation species (Spartina alterniflora) is being replaced with a mangrove foundation species (Avicennia germinans), forcing marsh fauna to rely on Avicennia for foundational support. We evaluated the interactions of two common and ecologically valuable basal consumers, fiddler crabs (Uca spp.) and marsh periwinkle snails (Littoraria irrorata), with both foundation species across sites with different levels of mangrove encroachment. By investigating both physical support, measured as habitat association and co-occurrence, and trophic support, as basal resource diet contributions, we found that Avicennia can physically replace Spartina for some consumers, but is not providing equivalent trophic support. Uca and Littoraria commonly occupy encroached sites and associate with mangroves but incorporate almost no mangrove plant matter into their diets. The ultimate consequences of a foundation shift in the case of mangrove encroachment may include shifting energy flows and resource use and decreased populations of basal consumers. Looking at interactions with foundation species from multiple perspectives is necessary to obtain a complete picture of the effects that foundational shifts are having, especially as such shifts are becoming increasingly common.
The Combined Effects of Road Salt and Biotic Stressors on Amphibian Sex Ratios
Aquatic systems worldwide are threatened by the anthropogenic use of synthetic chemicals, including pesticides, pharmaceuticals, and road de‐icers. Exposure to contaminants can alter the behavior, morphology, and physiology of organisms if it occurs during sensitive life stages. For instance, past studies have documented feminization of male amphibians following herbicide exposure and skewed sex ratios among amphibian populations exposed to road salt. However, many of these studies lack the complexities found within natural environments, such as competition with conspecifics or threat of predation, which are also known to influence development. Thus, it is important to understand how anthropogenic and natural stressors interact to alter animal sex ratios. Given the growing concern of secondary salinization of freshwater systems, we exposed larval wood frogs (Rana sylvatica) to either road salt (sodium chloride [NaCl]) or an alternative salt mixture (NaCl, magnesium chloride [MgCl2], and potassium chloride [KCl]) at 3 concentrations (200, 600, and 1000 mg Cl−/L) crossed with 3 biotic stressors (no‐stressor control, competition, or predator cues) to examine their potentially interactive effects on sex. Exposure to biotic stressors and NaCl did not influence wood frog sex ratios. In contrast, tadpole exposure to the intermediate salt mixture concentration significantly reduced the proportion of female frogs. Future studies are needed to determine whether such changes in sex are widespread among sensitive species with complex life cycles, and to assess the consequences of sex ratio changes on long‐term population dynamics.
Percent C, Percent N and C:N ratio for leaf samples from ITEX flux survey plots for 2003-2004, Toolik Alaska.
Foliar carbon and nitrogen concentrations of the dominant species from within the ITEX flux survey plots 2003-2004. Plots were located in the Toolik Lake LTER moist acidic tussock experiment plots in Alaska; at Imnavait Creek, Alaska.
Arctic LTER 1988: del 13C and del 15N ratios measurement for Eriophorum, Carex and lichen species in water tracks at Toolik and Imnavait Creek
del 13C and del 15N ratios were measured for plant and lichen in watertracks in the Toolik Lake drainage and the east facing slope of the Imnavait Creek area. Sampling locations for each species for a specific date were chosen across an elevation gradient starting from the lakeside and leading to ridge crest. The vegetation was dried and analyzed for stable isotopes.
Del 13C and del 15N ratios in a peat core at 2 cm depth intervals at 4 locations along the Dalton Highway, North Slope Alaska, 1989.
del 13C and del 15N ratios were measured on a peat core at 2 cm depth intervals. Peat cores were taken at Imnavait Creek, Pump Station 3, the Happy Valley Steram and Olikok Dock Road along the Dalton Highway, Alaska.
Del 13C ratios were measured for mosses collected from terrestrial, emergent and submerged sites in pond 13 of Imnavait Creek, North Slope Alaska 1990.
Del 13C ratios were measured for mosses collected from terrestrial, emergent and submerged sites in pond 13 of Imnavait Creek. Terrestrial mosses were collected from dry sites near the pond margin, emergent mosses were collected from the littoral zone of the pond and submerged mosses were collected from deep in the pond.
Concentration of dissolved inorganic carbon (DIC), carbon and nitrogen concentrations, C:N ratios and del 13C isotope value for lakes and rivers on North Slope from Brooks Range to Prudhoe Bay, Arctic LTER 1988 to 2005
Composite file describing plant, animal, water, and sediment samples collected at various sites near Toolik Research Station (68 38'N, 149 36'W). Sample site descriptors include an assigned number specific to the file, a number that relates the samples to other samples collected on the same date and time (sortchem), site, date, time, and depth. Samples are identified by type, category, and a short description. Data include isotope values, carbon and nitrogen concentrations, and C:N ratios of samples.
McMurdo Dry Valleys Isotope Ratios of Ice and Snow in Taylor Valley
As a part of the McMurdo Dry Valleys LTER program, isotope ratios have been determined from 295 ice/snow samples in Taylor Valley, Antarctica. Hydrogen/deuterium isotope ratios are given for all samples, and for a subset, there are oxygen isotope ratios, and a deuterium-excess. Values are reported relative to VSMOW, +/- 1.0 per mil for hydrogen, and +/- 0.1 for oxygen.
Isotope Ratios for Taylor Valley Streams
As a part of the McMurdo Dry Valleys LTER program, isotope ratios have been determined for 166 samples of stream water in Taylor Valley, Antarctica. Hydrogen/deuterium isotope ratios are given for all samples, and for a subset, there are oxygen isotope ratios, and a deuterium-excess. Values are reported relative to VSMOW, +/- 1.0 per mil for hydrogen, and +/- 0.1 for oxygen.
Shoot height and average carbon:nitrogen ratio for Spartina alterniflora in intertidal marshes on Hog Island, Parramore Island, Quinby inlet, and Phillips Creek of the Virginia Coast Reserve 1988-1989
Shoot height and average carbon:nitrogen ratio for Spartina alterniflora in intertidal marshes on Hog Island (Cattleshed Creek and Hodges Narrows), Parramore Island (Cresent Island: South Parramore), Quinby Inlet (Chimney Pole Marsh), and Phillips Creek (Phillips Creek) of the Virginia Coast Reserve 1988-1989.
Data from: A seasonal shift in offspring sex ratio of the brood parasitic Brown-headed Cowbird (Molothrus ater)
<p>Avian obligate brood parasites do not provide parental care for their eggs and young, and may therefore serve as a strong model system to test predictions of evolutionary sex-allocation theories, independent of parental modulation of primary sex ratios. However, none of the handful of previous studies examining offspring sex ratio in brood parasitic birds have revealed a bias from parity at the level of the female parasite, the host species, or temporal scale(s). This is also surprising, because in at least one brood parasite, the Brown-headed Cowbird (Molothrus ater), adult sex ratios are consistently and heavily male-biased. Here we used a large database of embryonic and nestling cowbirds' genetic sex ratios collected from nests of a single host species, the Prothonotary Warbler (Protonotaria citrea) to assess potential overall, temporal, and individual patterns of bias. Contrary to previous findings, we documented an increase in the calculated male sex ratios later in the breeding season. There was no effect of whether embryos or nestlings were sampled, implying a lack of host parental effect on shifting the primary-to-secondary sex ratios of brood parasitic offspring. Future work should explore the sex-specific survival and recruitment pattern of fledgling cowbirds raised by this and other host species to reconcile theoretical and empirical predictions and patterns.</p>
Data from: Influence of intra- and interspecific variation in predator-prey body size ratios on trophic interaction strengths
<p>1. Predation is a pervasive force that structures food webs and directly influences ecosystem functioning. The relative body sizes of predators and prey may be an important determinant of interaction strengths. However, studies quantifying the combined influence of intra- and interspecific variation in predator-prey body size ratios are lacking.</p> <p>2. We use a comparative functional response approach to examine interaction strengths between three size classes of invasive bluegill and largemouth bass towards three scaled size classes of their tilapia prey. We then quantify the influence of intra- and interspecific predator-prey body mass ratios on the scaling of attack rates and handling times.</p> <p>3. Type II functional responses were displayed by both predators across all predator and prey size classes. Largemouth bass consumed more than bluegill at small and intermediate predator size classes, whilst large predators of both species were more similar. Small prey were most vulnerable overall, however differential attack rates among prey were emergent across predator sizes. For both bluegill and largemouth bass, small predators exhibited higher attack rates towards small and intermediate prey sizes, whilst larger predators exhibited greater attack rates towards large prey. Conversely, handling times increased with prey size, with small bluegill exhibiting particularly low feeding rates towards medium-large prey types. Attack rates for both predators peaked unimodally at intermediate predator-prey body mass ratios, whilst handling times generally shortened across increasing body mass ratios.</p> <p>4. We thus demonstrate effects of body size ratios on predator-prey interaction strengths between key fish species, with attack rates and handling times dependent on the relative sizes of predator-prey participants.</p> <p>5. Considerations for intra- and interspecific body size ratio effects are critical for predicting the strengths of interactions within ecosystems and may drive differential ecological impacts among invasive species as size ratios shift.</p>
Data from: Detecting the population dynamics of an autosomal sex-ratio distorter transgene in malaria vector mosquitoes
<p>1. The development of genetically modified mosquitoes and their subsequent field release offers innovative and cost-effective approaches to reduce mosquito-borne diseases, such as malaria. A sex-distorting autosomal transgene has been developed recently in G3 mosquitoes, a lab strain of the malaria vector Anopheles gambiae s.l. The transgene expresses an endonuclease called I-PpoI during spermatogenesis, which selectively cleaves the X chromosome to result in ~95% male progeny. Following the World Health Organization Guidance Framework for the testing of genetically modified mosquitoes, we assessed the dynamics of this transgene in large cages using a joint experimental-modelling approach.</p> <p>2. We performed a four-month experiment in indoor large cages to study the population genetics of the transgene. The cages were set up to mimic a simple tropical environment with a diurnal light-cycle, constant temperature, and constant humidity. We allowed the generations to overlap to engender a stable age structure in the populations. We constructed a model to mimic the experiments, and used the experimental data to infer the key model parameters.</p> <p>3. We identified two fitness costs associated to the transgene. First, transgenic adult males have reduced fertility and, second, their female progeny have reduced pupal survival rates. Our results demonstrate that the transgene is likely to disappear in less than three years under our confined conditions. Model predictions suggest this will be true over a wide range of background population sizes and transgene introduction rates.</p> <p>4. Synthesis and applications: Our semi-field indoor cage experiments are in line with WHO guidance recommendations in regards to the development and testing of self-limiting technologies. Since the transgenic strain (Ag(PMB)1) has been considered for genetic vector control of malaria, our results are fundamentally important for determining expectations on the persistence of the transgene post-release. Our results provide a demonstration of the self-limiting nature of the transgene, and indicate that longevity will be further reduced by fitness costs that were not previously identified. Finally, our study has showcased an alternative and effective method for characterising the phenotypic expression of a transgene in an insect pest population.</p>
Quantifying tensions in cosmological parameters: Interpreting the DES evidence ratio (supplementary inference products)
<p>These are the nested sampling inference products and input files that were used to compute results for <a href="https://arxiv.org/abs/1902.04029">arXiv:1902.04029</a> and <a href="https://arxiv.org/abs/1903.06682">arXiv:1903.06682</a></p> <p>An example plotting script and plots from the papers are included to demonstrate usage.</p> <p>Filename conventions:</p> <p>runs_default: default prior widths</p> <p>runs_narrow: narrowest prior widths</p> <p>runs_medium: intermediate prior widths</p> <p>planck: Planck 2018 baseline likelihoods</p> <p>SH0ES: Riess et al 2018 Hubble likelihood</p> <p>BAO: BOSS DR12 baryonic acoustic oscillations + redshift space distortion likelihood</p> <p>DES: Dark Energy Survey Y1 baseline</p> <p>Software used:</p> <p>CosmoChord <a href="https://github.com/williamjameshandley/CosmoChord/tree/e2f7020bd9d4254230097037fb6ebaee95a3d558">https://github.com/williamjameshandley/CosmoChord/tree/e2f7020bd9d4254230097037fb6ebaee95a3d558</a></p>
Sex-specific patterns of senescence in artificial insect populations varying in sex-ratio to manipulate reproductive effort
<p><strong>Background:</strong> The disposable soma theory of ageing assumes that organisms optimally trade-off limited resources between reproduction and longevity to maximize fitness. Early reproduction should especially trade-off against late reproduction and longevity because of reduced investment into somatic protection, including immunity. Moreover, as optimal reproductive strategies of males and females differ, sexually dimorphic patterns of senescence may evolve. In particular, as males gain fitness through mating success, sexual competition should be a major factor accelerating male senescence. In a single experiment, we examined these possibilities by establishing artificial populations of the mealworm beetle, <em>Tenebrio molitor</em>, in which we manipulated the sex-ratio to generate variable levels of investment into reproductive effort and sexual competition in males and females.</p> <p><strong>Results:</strong> As predicted, variation in sex-ratio affected male and female reproductive efforts, with contrasted sex-specific trade-offs between lifetime reproduction, survival and immunity. High effort of reproduction accelerated mortality in females, without affecting immunity, but high early reproductive success was observed only in balanced sex-ratio condition. Male reproduction was costly on longevity and immunity, mainly because of their investment into copulations rather than in sexual competition.</p> <p><strong>Conclusions:</strong> Our results suggest that <em>T. molitor</em> males, like females, maximize fitness through enhanced longevity, partly explaining their comparable longevity. </p>
Pretreatment Neutrophil-to-Lymphocyte Ratio, Mutational Load, and Outcomes in Patients Treated with Immune Checkpoint Inhibitors
<p>This dataset has been used to analyze the association between pre-treatment neutrophil-to-lymphocyte ratio and tumour mutational burden with survival and response to treatment in immunotherapy-treated patients with cancer. The dataset contains clinical and genomic data for 2,037 patients with 18 cancer types.</p>
Dataset: Quasi-static shear-compression tests on stone masonry walls with plaster: Influence of load history and axial load ratio
<p>This repository contains the results of six quasi-static cyclic shear-compression tests performed on single-leaf stone masonry walls made of limestone blocks and lime-based mortar joints. Of the six walls, four are tested under different axial load ratios, performing a cyclic load history with two cycles per increasing drift demand. Three are tested under the same axial load ratio but are subjected to different load histories, namely, one monotonic loading, one cyclic loading with two cycles per drift level and one cyclic loading with one hundred cycles per drift level.</p> <p>Results and details of the tests are reported in:</p> <blockquote> <p>Godio M, Vanin F, Zhang S, Beyer K (2019). “Quasi-Static Shear-Compression Tests on Stone Masonry Walls with Plaster: Influence of Load History and Axial Load Ratio.” Engineering Structures 192: 264–78. <a href="https://doi.org/10.1016/j.engstruct.2019.04.041">https://doi.org/10.1016/j.engstruct.2019.04.041</a> </p> </blockquote>
Data from: The sources of variation for individual prey-to-predator size ratios
<p>The relative body size at which predators are willing to attack prey, a key trait for predator-prey interactions, is usually considered invariant. However, this ratio can vary widely among individuals or populations. Identifying the range and origin of such variation is key to understanding the strength and constraints on selection in both predators and prey. Still, these sources of variation remain largely unknown. We filled this gap by measuring the genetic, maternal and environmental variation of the maximum prey-to-predator size ratio (PPSRmax) in juveniles of the wolf spider Lycosa fasciiventris using a paternal half-sib split brood design, in which each male was paired with two different females and the offspring reared in two different food environments: poor and rich. Each juvenile spider was then sequentially offered crickets of decreasing size and the maximum prey size killed was determined. We also measured body size and body condition of spiders upon emergence and just before the trial. We found low, but significant heritability (h2=0.069) and dominance and common environmental variance (d2+4c2=0.056). PPSRmax was also partially explained by body condition (during trial) but there was no effect of the rearing food environment. Finally, a maternal correlation between body size early in life and PPSRmax indicated that offspring born larger were less predisposed to feed on larger prey later in life. Therefore, PPSRmax, a central trait in ecosystems, can vary widely and this variation is due to different sources, with important consequences for changes in this trait in the short and long terms.</p>
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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.
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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.
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