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13,017 results for “Positionning”
Social network position experiences more variable selection than weaponry in wild subpopulations of forked fungus beetles
<p>1. The phenotypic expression and fitness consequences of behaviors that are exhibited during social interactions are especially sensitive to their local social context. This context-dependence is expected to generate more variation in the sign and magnitude of selection on social behavior than that experienced by static characters like morphology. Relatively few studies, however, have examined selection on behavioral traits in multiple populations. 2. We estimated sexual selection in the wild to determine if the strength and form of selection on social phenotypes is more variable than that on morphology. 3. We compared selection gradients on social network position, body size, and weaponry of male forked fungus beetles (Bolitotherus cornutus) as they influenced mating success across nine natural subpopulations. 4. Male horn length consistently experienced positive sexual selection. However, the sign and magnitude of selection on individual measures of network centrality (strength and betweenness) differed significantly among subpopulations. Moreover, selection on social behaviors occurred at local scale ("soft selection"), whereas selection on horn length occurred at the metapopulation scale ("hard selection"). 5. These results indicate that an individual with a given social phenotype could experience different fitness consequences depending on the network it occupies. While individuals seem to be unable to escape the fitness effects of their morphology, they may have the potential to mediate the pressures of selection on behavioral phenotypes by moving among subpopulations or altering social connections within a network.</p>
Positive and negative interspecific interactions between coexisting rice planthoppers neutralize the effects of elevated temperatures
Global warming is often predicted to increase damage to plants through direct effects on insect herbivores. However, the indirect impacts of rising temperatures on herbivores, mediated through interactions with their biotic environment, could dampen these effects. Using a series of reciprocal density experiments with gravid females and developing nymphs, we examined interspecific competition between two coexisting phloem feeders, Nilaparvata lugens (BPH) and Sogatella furcifera (WBPH), on rice at 25°C and 30°C. WBPH performed better (i.e., adults survived longer, nymphs developed faster and grew larger) at 25°C and BPH (i.e., nymphs developed faster) at 30°C. However, contrary to predictions, WBPH had a greater effect in reducing oviposition and nymph performance in BPH at 30°C. A decoupling of resource use by WBPH and its antagonistic effects on BPH at the higher temperature suggests that WBPH feeding induces host defenses that reduce BPH fitness (i.e., interference competition). Meanwhile, BPH facilitated WBPH oviposition at 30°C and facilitated WBPH nymph performance at 25 and 30°C. Greater facilitation of feeding in WBPH nymphs by BPH at high densities suggests that mechanical damage and host responses to damage increased the fitness of the heterospecific nymphs. Although BPH also facilitated egg-laying by WBPH, intra- and interspecific crowding countered this facilitation at both temperatures. Simulated life tables for planthoppers at 25 and 30°C depicted significantly lower offspring numbers on rice infested by WBPH alone and from mixed BPH-WBPH infestations than from infestations by BPH alone. Our results indicate how interference competition – mediated through host plant defenses - can increase ecosystem resilience to the warmer temperatures predicted under global climate change.
Positive selection and inactivation in vision and hearing genes of cetaceans
<p>The transition to an aquatic lifestyle in cetaceans (whales and dolphins) resulted in a radical transformation in their sensory systems. Toothed whales acquired specialized high-frequency hearing tied to the evolution of echolocation, while baleen whales evolved low-frequency hearing. More generally, all cetaceans show adaptations for hearing and seeing underwater. To determine the extent to which these phenotypic changes have been driven by molecular adaptation, we performed large-scale targeted sequence capture of 179 sensory genes across the Cetacea, incorporating up to 54 cetacean species from all major clades as well as their closest relatives, the hippopotamuses. We screened for positive selection in 167 loci related to vision and hearing, and found that the diversification of cetaceans has been accompanied by pervasive molecular adaptations in both sets of genes, including several loci implicated in non-syndromic hearing loss (NSHL). Despite these findings, however, we found no direct evidence of positive selection at the base of odontocetes coinciding with the origin of echolocation, as found in studies examining fewer taxa. By using contingency tables incorporating taxon- and gene-based controls, we show that, while numbers of positively selected hearing and NSHL genes are disproportionately high in cetaceans, counts of vision genes do not differ significantly from expected values. Alongside these adaptive changes, we find increased evidence of pseudogenization of genes involved in cone-mediated vision in mysticetes and deep diving odontocetes. </p>
Weed dataset - Crop diversity Experiment - Crop-weed relationships are context-dependent and cannot fully explain the positive effects of intercropping on yield
<p>This shows the weed mass per species and crop yield per species of each plot described in the experiment. </p>
Positive genetic covariance between male sexual ornamentation and fertilizing capacity
<p>Postcopulatory sexual selection results from variation in competitive fertilization success among males, and comprises powerful evolutionary forces that operate after the onset of mating [1, 2]. Theoretical advances in the field of sexual selection addressing the build-up and co-evolutionary consequences of genetic coupling [3-5], motivate the hypothesis that indirect postcopulatory sexual selection may promote evolution of male secondary sexual traits—those traits traditionally ascribed to mate choice and male fighting [6, 7]. A crucial prediction of this hypothesis is genetic covariance between trait expression and competitive fertilization success, which has been predicted to arise, for example, when traits subject to pre- and postcopulatory sexual selection are under positive correlational selection [8]. We imposed bidirectional artificial selection on male ornament (sex comb) size in <i>Drosophila bipectinata</i>, and demonstrate increased competitive fertilization success as a correlated evolutionary response to increasing ornament size. Transcriptional analyses revealed that levels of specific seminal fluid proteins repeatedly shifted in response to this selection, suggesting that properties of the ejaculate rather than the enlarged sex comb itself contributed fertilizing capacity. We used ultraprecise laser surgery to reduce ornament size of high line males, and found that their fertilizing superiority persisted despite the size reduction, reinforcing the transcriptional results. The data support the existence of positive genetic covariance between a male secondary sexual trait and competitive fertilization success, and suggest the possibility that indirect postcopulatory sexual selection may under certain conditions magnify net selection on ornamental trait expression. </p>
Elevated rates of positive selection drive the evolution of pestiferousness in the Colorado potato beetle ( Leptinotarsa decemlineata, Say)
<p class="Paragraph">In order to understand the evolution of pestiferousness, which we define as the accumulation of traits that contribute to an insect population's success in an agroecosystem, we tested the importance of known genomic properties associated with rapid adaptation. Within the leaf beetle genus <i>Leptinotarsa</i>, only the Colorado potato beetle (CPB), <i>Leptinotarsa decemlineata</i> Say, and a few populations therein, has risen to pest status on cultivated nightshades, <i>Solanum</i>. Using whole genomes from ten closely related <i>Leptinotarsa</i> species native to the United States we reconstructed a high-quality species tree and used this phylogenetic framework to assess evolutionary patterns in four genomic features of rapid adaptation: standing genetic variation, gene family expansion and contraction, transposable element variation, and positive selection at protein coding genes. Throughout approximately 20 million years of history, <i>Leptinotarsa</i> species show little evidence of gene family turnover and transposable element variation. However, there is a clear pattern of recently derived lineages, including CPB, experiencing higher rates of positive selection on protein coding genes. We determine these rates are associated with greater standing genetic variation due to larger effective population size, which support the theory that the demographic history contributes to rates of protein evolution. Furthermore, we identify a suite of genes under positive selection that are linked to pestiferousness, exclusively, in the Colorado potato beetle lineage. They are involved in the biological processes of xenobiotic detoxification, chemosensation, and hormone function.</p>
Thunderstorm_Lower_Positive_Charge_Data
<p>Data and instructions on how to produce the figures in an article</p> <p>titled "Thunderstorm lower positive charge and triggered negative lightning-leaders"</p> <p>to be submitted to the Journal of Geophysical Research, Atmospheres.</p> <p>Triggered negative leaders propagated into thunderstorm lower positive charge. Current</p> <p>measured at the ground where the triggering wire was attached and an estimate of</p> <p>the volume occupied by the branched leaders give an average charge density in the lower</p> <p>positive region. </p>
FIG. 6 in Trophic position of some Late Devonian-Carboniferous (Mississippian) conodonts revealed on carbon organic matter isotope signatures: a case study of the East European basin
FIG. 6. — Bivariate plot for bulk carbonate δ13Cand conodont δ13Cvalues. carb org
FIG. 4 in Trophic position of some Late Devonian-Carboniferous (Mississippian) conodonts revealed on carbon organic matter isotope signatures: a case study of the East European basin
FIG. 4. — Organic carbon isotope compositions of conodonts measured in the study.
Data Sets and Code for Simple formulas for pseudoposition for electrical resistivity and IP in vertical boreholes based on mean positions of the sensistivity
<p>Data and Matlab code in figures.</p>
Data from: Phenotype-environment matching predicts both positive and negative effects of intraspecific variation
Natural populations can vary considerably in their genotypic and/or phenotypic diversity. Differences in this intraspecific diversity can have important consequences for contemporary ecological dynamics, but the direction and magnitude of these effects appear inconsistent across studies and systems. Here we proposed and tested the hypothesis that context-dependent ecological effects of altering phenotypic variance are predictable and arise from the relationship between a population's mean phenotype and the local environmental optimum. By factorially manipulating the mean and variance of a key host trait in environments with and without a lethal parasite, we demonstrate that increasing phenotypic variance can have beneficial effects for host populations (e.g. smaller disease epidemics), but only when the population's initial phenotype was poorly-matched to the local environment. When phenotypes were initially well-suited to environmental conditions, in contrast, greater phenotypic variance led to larger disease epidemics. Significant reductions in individual susceptibility occurred in both contexts over time, but the mechanisms leading to those reductions differed; strong selection was caused by either a 'suboptimal' trait mean and insufficient trait variance, or a 'near-optimal' trait mean and too much trait variance. Increasing intraspecific variation is clearly not always beneficial for populations, instead producing predictable ecological and evolutionary effects that depend on environmental context and biological interactions.
Drought survival is positively associated with high turgor loss points in temperate perennial grassland species
<p>1. Turgor loss point (π<sub>tlp</sub>) has been suggested to be a key trait for drought resistance in woody species. In herbaceous grassland species the role of π<sub>tlp</sub> for species drought survival has not yet been tested, although grasslands are projected to experience more frequent and intense droughts with climate change.</p> <p>2. To gain insights into the role of π<sub>tlp</sub> for drought resistance of temperate perennial grassland species, we assessed π<sub>tlp</sub> of 41 species common in Germany (20 forbs, 21 grasses). We directly related them to the species' comparative whole-plant drought survival and midday leaf water potentials under drought (Ψ<sub>MD</sub>) assessed in a common garden drought experiment, and to species moisture association.</p> <p>3. Species drought survival increased with increasing π<sub>tlp</sub> across all species as well as within forbs or grasses separately. Ψ<sub>MD</sub> was positively related to π<sub>tlp</sub> and drought survival. Our results imply that high π<sub>tlp</sub> promotes drought survival of common perennial European temperate mesic grassland species by enabling them to maintain high leaf water potentials under drought, i.e., a desiccation avoidance strategy. However, π<sub>tlp</sub> was not related to species moisture association.</p> <p>4. The positive relationship between π<sub>tlp</sub> and drought survival in herbaceous grassland species was opposite to the negative relationship previously established in woody plants, implying that mechanisms of drought resistance differ between woody and herbaceous species. Our results highlight the necessity of directly testing the relationship of functional traits to whole-plant drought survival in different plant life forms, before using trait assessments for predicting plant responses to drought.</p>
Data from: Mycorrhizal feedbacks generate positive frequency dependence accelerating grassland succession
1. Plant mutualists including arbuscular mycorrhizal (AM) fungi have been postulated as being important drivers of plant community diversity and succession. Late successional plants have been shown to be more responsive to AM fungi and more sensitive to AM fungal species identity, which could generate positive feedback and potentially accelerate succession. 2. We test the effect of AM fungi on plant diversity and on frequency dependence predicted by positive plant‐AM fungi feedback across a successional gradient. We created prairie mesocosms comprised of a majority early‐successional, equal abundance and a majority late successional plant species. We inoculated these mesocosms and a field restoration experiment with 14 different communities of AM fungi from late successional prairies that varied in levels of species richness. 3. Overall, we found that AM fungi increased plant diversity and this was driven by the response of late successional plant species to mycorrhizae. Our results indicate that AM fungal composition is more important than AM fungal diversity per se. We found that the effect of inoculation with a single species or groups of AM fungi depended on whether those fungi benefited late successional plant species. Early successional plants consistently exhibited negative frequency dependent growth regardless of fungal composition, while late successional plants demonstrated positive frequency dependent growth in our mesocosms—but only in the presence of beneficial AM fungal species. These results are consistent with positive plant‐mycorrhizal feedbacks accelerating plant community successional trajectories once late successional plants establish. Mesocosm results were mirrored with field inoculation assays where we found that beneficial AM fungi facilitated late successional plant establishment. 4. Synthesis. Our results provide support for beneficial AM fungi being a primary mechanism for positive plant‐soil feedback driving plant community succession, as late successional seedlings grew faster and larger when their neighbors were also late successional plant species when they were associated with beneficial AM fungi. We found that this positive feedback thereby accelerated succession in mesocosms and in the field.
Data from: Pest control potential of adjacent agri-environment schemes varies with crop type and is shaped by landscape context and within-field position
<ol> <li>Increasing natural pest control in agricultural fields is an important aim of ecological intensification. Combined effects of landscape context and local placement of agri-environmental schemes on natural pest control and within field distance functions of natural pest control agents have rarely been addressed but might affect the distribution of biocontrol providers. Importantly, it is currently unknown whether ecosystem services provided by adjacent agri-environmental schemes (AES) are consistent for different crop types during crop rotation.</li> <li>In this study, we assessed whether crop rotation from oilseed rape to cereals altered within-field distance functions of ground dwelling predators from adjacent agri-environmental fields along a gradient in landscape context. Additionally we recorded crop pests, predation rates, parasitoids as well as crop yields on a total of 30 study sites.</li> <li>Distance functions varied between trophic levels: Carabid richness decreased while densities of carabid beetles, staphylinid beetles as well as crop yields increased towards the field centres. Distance functions of parasitoids and pests were modulated by the amount of semi-natural habitat in the surrounding landscape, while the effects of adjacent AES were limited.</li> <li>Distance decay functions found for ground dwelling predators in oilseed rape in the previous year were not always present in cereals. Increasing distance to the field edge also increased effects of crop rotation on carabid beetle assemblages, indicating a source habitat function of field edges.</li> <li>Synthesis and applications<i>.</i> Distance functions of natural pest control are not universal and the effects of agri-environmental schemes (AES) in different adjacent crops during crop rotation vary and depends on ecological contrasts. A network of semi-natural habitats and spatially optimised AES habitats can benefit pest control in agricultural landscapes, but constraints as a result of crop type need to be addressed by annually targeted, spatially shifting AES schemes for different crops.</li> </ol> <div> </div>
Positive species interactions strengthen in a high-CO2 ocean
<p>Negative interactions among species are a major force shaping natural communities and are predicted to strengthen as climate change intensifies. Similarly, positive interactions are anticipated to intensify, and could buffer the consequences of climate-driven disturbances. We used in situ experiments at volcanic CO2 vents within a temperate rocky reef to show that ocean acidification can drive community reorganization through indirect and direct positive pathways. A keystone species, the algal-farming damselfish Parma alboscapularis, enhanced primary productivity through its weeding of algae whose productivity was also boosted by elevated CO2. The accelerated primary productivity translated into increased densities of primary consumers (herbivorous invertebrates), which indirectly supported increased secondary consumers densities (predatory fish) (i.e. strengthening of bottom-up fuelling). However, this keystone species also reduced predatory fish densities through behavioural interference, releasing invertebrate prey from predation pressure and enabling a further boost in prey densities (i.e. weakening of top-down control). We uncover a novel mechanism where a keystone herbivore mediates bottom-up and top-down processes simultaneously to boost populations of a co-existing herbivore, resulting in altered food web interactions and predator populations under future ocean acidification.</p>
Data from: Methylation of avpr1a in the cortex of wild prairie voles: effects of CpG position and polymorphism
DNA methylation can cause stable changes in neuronal gene expression, but we know little about its role in individual differences in the wild. In this study, we focus on the vasopressin 1a receptor (avpr1a), a gene extensively implicated in vertebrate social behaviour, and explore natural variation in DNA methylation, genetic polymorphism and neuronal gene expression among 30 wild prairie voles (Microtus ochrogaster). Examination of CpG density across 8 kb of the locus revealed two distinct CpG islands overlapping promoter and first exon, characterized by few CpG polymorphisms. We used a targeted bisulfite sequencing approach to measure DNA methylation across approximately 3 kb of avpr1a in the retrosplenial cortex, a brain region implicated in male space use and sexual fidelity. We find dramatic variation in methylation across the avrp1a locus, with pronounced diversity near the exon–intron boundary and in a genetically variable putative enhancer within the intron. Among our wild voles, differences in cortical avpr1a expression correlate with DNA methylation in this putative enhancer, but not with the methylation status of the promoter. We also find an unusually high number of polymorphic CpG sites (polyCpGs) in this focal enhancer. One polyCpG within this enhancer (polyCpG 2170) may drive variation in expression either by disrupting transcription factor binding motifs or by changing local DNA methylation and chromatin silencing. Our results contradict some assumptions made within behavioural epigenetics, but are remarkably concordant with genome-wide studies of gene regulation.
Data from: Livestock overgrazing disrupts the positive associations between soil biodiversity and nitrogen availability
Livestock overgrazing influences both microbial communities and nutrient cycling in terrestrial ecosystems. However, the role of overgrazing in regulating the relationship between soil biodiversity and nitrogen availability remains largely unexplored. We performed long-term grazing exclusion experiments across eight sites along precipitation gradient covering three major types of grassland in northern China to compare the linkage between soil microbial diversity and N availability in overgrazed versus non-grazed conditions. We found a positive association between fungal diversity and soil available N in non-grazed grasslands. However, the positive association was absent in overgrazed environments. Bacterial diversity is not related to soil available N in either non-grazed or overgrazed grasslands. Moreover, in bacterial community, we found a positive link between the relative abundance of Actinobacteria with soil available N in non-grazed, but not overgrazed, grasslands. Instead we found the links between relative abundance of Bacteroidetes and Acidobacteria with soil available N in overgrazed grasslands, but not non-grazed, grasslands. Our work provides evidence that the relationships between microbial diversity and ecosystem functions are context-dependent, and so microbial community diversity is likely not the major driver of soil N mineralization in overgrazed grasslands. Our study suggests that high intensity anthropogenic activities in grasslands restrains the capacity of diverse soil microbial communities to sustain ecosystem function, and more broadly the capacity of entire ecosystems to maintain important ecosystem processes such as plant production. Our study also indicates that the fundamental microbial communities associated with N availability change with differing land management strategies (e.g. livestock grazing).
Data from: Influence of range position on locally adaptive gene-environment associations in Populus flowering time genes
Local adaptation is pervasive in forest trees, which are characterized by large effective population sizes spanning broad climatic gradients. In addition to having relatively contiguous populations, many species also form isolated populations along the rear edge of their range. These rear-edge populations may contain unique adaptive diversity reflecting a history of selection in marginal environments. Thus, discovering genomic regions conferring local adaptation in rear edge populations is a key priority for landscape genomics to ensure conservation of genetic resources under climate change. Here, we report on adaptive gene-environment associations in SNPs from 27 genes in the Populus flowering time gene network, analyzed on a range-wide collection of >1000 balsam poplar trees, including dense sampling of the southern range edge. We use a combined approach of local adaptation scans to identify candidate SNPs, followed by modeling the compositional turnover of adaptive SNPs along multivariate climate gradients using Gradient Forests (GF). Flowering time candidate genes contained extensive evidence of climate adaptation, namely outlier population structure and gene-environment associations, along with allele frequency divergence between the core and edge of the range. GF showed strong allele frequency turnover along gradients of elevation and diurnal temperature variability, as well as threshold responses to summer temperature and precipitation, with turnover especially strong in edge populations that occur at high elevation but southerly latitudes. We discuss these results in light of how climate may disrupt locally adaptivegene-environment relationships, and suggest that rear edge populations hold climate-adaptive variants that should be targeted for conservation.
Eastern Canada Flocks: Images and manually annotated bird positions
The Eastern Canada (ECA) Flocks data set consists of manually annotated Images from the Common Eider (COEI, Somateria mollissima) Winter Survey and the Greater Snow Geese (GSGO, Anser caerulescens atlanticus) Spring Survey. The images were taken in Eastern Canada using fixed-wing aircraft and manually annotated with ImageJ's Cell counter plugins. We selected and annotated the ECA Flocks images in order to test the precision of the CountEm flock size estimation method. ECA Flocks includes 179 COEI and 99 GSGO single flock images. We cut each image manually to a rectangle that excluded large parts of the image with no birds. Both versions (original and cut) of each image are available in the data set. We manually annotated 637,555 (124,309 COEI and 514,235 GSGO) bird positions in the cut images from both surveys. Each bird has an associated "Type" which refers to species and/or sex. Sex identification was only possible for adult common eiders since females and immature males are brown birds whereas adult males have mainly white plumage. 64,484 male and 58,029 females were identified in the COEI images, as well as 1796 birds of other species. 504,891 Snow Geese and 9344 birds of other species were labeled in the GSGO images. A .csv file including all annotated bird positions and types is available for each image. The COEI and GSGO photos of the ECA Flocks data set were taken in the years 2006 and 2018 and 2016-2018 respectively. We selected these photos in order to include images with different quality and resolution. COEI and GSGO flock sizes range from 6 to 4,154 and from 43 to 36, 241 respectively. There is high variability in light conditions, backgrounds, number and spatial arrangement of birds across the images. The data set is therefore potentially useful to test the precision of methods for analyzing imagery to estimate the abundance of animals by directly detecting, identifying and counting individuals.
An invasive amphibian drives antipredator responses in two prey at different trophic positions
<p>Generalist invasive predators consume prey at different trophic levels and generate drastic changes in local communities. However, the long-term effects of predation may be reduced by eco-evolutionary responses of native populations. The capacity of prey species distributed across the trophic network to develop antipredator responses may determine the ecosystem potential to buffer against the invader. The African clawed frog is a major invader on several continents. Because of its large size, generalist diet, and aquatic lifestyle, we predicted the development of antipredator responses in prey species at different trophic levels. We tested for behavioral shifts between populations within and outside the invasive range in the herbivorous snail Physella acuta and the predatory heteropteran, the backswimmer Notonecta glauca. We detected antipredator responses in both prey species. In sympatry, P. acuta stayed higher in the water column, while N. glauca spent more time swimming underwater and less time surfacing when the predator cues were present. In allopatry, P. acuta dived deeper and N. glauca spent more time surfacing and stayed longer still underwater. In both species, sympatric populations showed evidence of olfactory recognition of the frog. Our results show that the introduction of a top predator like Xenopus laevis in the pond ecosystem drives behavioral antipredator responses in species across the trophic network. Eco-evolutionary processes may allow some degree of long-term resilience of pond communities to the invasion of X. laevis.</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.
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.