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6,861 results for “Animation”
Data from: Interactive life-history traits predict sensitivity of plants and animals to temporal autocorrelation
Temporal autocorrelation in demographic processes is an important aspect of population dynamics, but a comprehensive examination of its effects on different life-history strategies is lacking. We use matrix populations models from 454 plant and animal populations to simulate stochastic population growth rates (log λs) under different temporal autocorrelations in demographic rates, using simulated and observed covariation among rates. We then test for differences in sensitivities, or changes, of log λs to changes in autocorrelation among two major axes of life-history strategies, obtained from phylogenetically-informed principal component analysis: the fast-slow and semelparous-iteroparous continua. Fast life histories exhibit highest sensitivities to simulated autocorrelation in demographic rates across reproductive strategies. Slow life histories are less sensitive to temporal autocorrelation, but their sensitivities increase among highly iteroparous species. We provide cross-taxonomic evidence that changes in the autocorrelation of environmental variation may affect a wide range of species, depending on complex interactions of life-history strategies.
Data from: From animal tracks to fine-scale movement modes: a straightforward approach for identifying multiple, spatial movement patterns
1. Thanks to developments in animal tracking technology, detailed data on the movement tracks of individual animals are now attainable for many species. However, straightforward methods to decompose individual tracks into high-resolution, spatial modes are lacking but are essential to understand what an animal is doing. 2. We developed an analytical approach that combines separately-validated methods into a straightforward tool for converting animal GPS tracks to short-range movement modes. Our three-step analytical process comprises: (1) decomposing data into separate movement segments using behavioural change point analysis; (2) defining candidate movement modes and translating them into non-linear or linear equations between net squared displacement (NSD) and time; and (3) fitting each candidate equation to NSD segments and determining the best-fitting modes using Concordance Criteria, Akaike's Information Criteria and other fine-scale segment characteristics. We illustrate our approach for three sub-adults, male wild boar Sus scrofa tracked at 15 min intervals over 4 months using GPS collars. We defined five candidate movement modes based on previously published studies of short-term movements: encamped, ranging, round trips (complete and partial), and wandering. 3. Our approach successfully classified over 80% of the tracks into these movement modes lasting between 5 and 54 hours and covering between 300 m to 20 km. Repeated analyses of GPS data resampled at different rates indicated that one positional fix every 3-4 h was sufficient for >70% classification success. Classified modes were consistent with published observations of wild boar movement, further validating our method. 4. The proposed approach advances the status quo by permitting classification into multiple movement modes (where these are adequately discernable from spatial fixes) facilitating analyses at high temporal and spatial resolutions, and is straightforward, largely objective, and without restrictive assumptions, necessary parameterizations or visual interpretation. Thus, it should capture the complexity and variability of tracked animal movement mode for a variety of taxa across a wide range of spatial and temporal scales.
Data from: Building genetic networks using relatedness information: a novel approach for the estimation of dispersal and characterization of group structure in social animals
Natal dispersal is an important life history trait driving variation in individual fitness and, therefore, a proper understanding of the factors underlying dispersal behaviour is critical to many fields including population dynamics, behavioural ecology and conservation biology. However, individual dispersal patterns remain difficult to quantify despite many years of research using direct and indirect methods. Here, we quantify dispersal in a single intensively-studied population of the cooperatively breeding chestnut-crowned babbler (Pomatostomus ruficeps) using genetic networks created from the combination of pairwise relatedness data and social networking methods and compare this to dispersal estimates from re-sighting data. Not only does this novel approach identify movements between social groups within our study sites but also provides an estimation of immigration rates of individuals originating outside the study site. Both genetic and re-sighting data indicated that dispersal was strongly female-biased, but the magnitude of dispersal estimates was much greater using genetic data. This suggests that many previous studies relying on mark-recapture data may have significantly underestimated dispersal. An analysis of spatial genetic structure within the sampled population also supports the idea that females are more dispersive, with females having no structure beyond the bounds of their own social group while male genetic structure expands for 750 meters from their social group. Although the genetic network approach we have used is an excellent tool for visualising the social and genetic microstructure of social animals and identifying dispersers, our results also indicate the importance of applying them in parallel with behavioural and life history data.
Data from: Synergistic effects of fire and elephants on arboreal animals in an African savannah
1. Disturbance is a crucial determinant of animal abundance, distribution and community structure in many ecosystems, but the ways in which multiple disturbance types interact remain poorly understood. The effects of multiple-disturbance interactions can be additive, subadditive or super-additive (synergistic). Synergistic effects in particular can accelerate ecological change; thus, characterizing such synergies, the conditions under which they arise, and how long they persist has been identified as a major goal of ecology. 2. We factorially manipulated two principal sources of disturbance in African savannas, fire and elephants, and measured their independent and interactive effects on the numerically dominant vertebrate (the arboreal gekkonid lizard Lygodactylus keniensis) and invertebrate (a guild of symbiotic Acacia ants) animal species in a semi-arid Kenyan savanna. 3. Elephant exclusion alone (minus fire) had negligible effects on gecko density. Fire alone (minus elephants) had negligible effects on gecko density after 4 months, but increased gecko density twofold after 16 months, likely because the decay of fire-damaged woody biomass created refuges and nest sites for geckos. In the presence of elephants, fire increased gecko density nearly threefold within 4 months of the experimental burn; this occurred because fire increased the incidence of elephant damage to trees, which in turn improved microhabitat quality for geckos. However, this synergistic positive effect of fire and elephants attenuated over the ensuing year, such that only the main effect of fire was evident after 16 months. 4. Fire also altered the structure of symbiotic plant-ant assemblages occupying the dominant tree species (Acacia drepanolobium); this influenced gecko habitat selection but did not explain the synergistic effect of fire and elephants. However, fire-driven shifts in plant-ant occupancy may have indirectly mediated this effect by increasing trees' susceptibility to elephant damage. 5. Our findings confirm the importance of fire × elephant interactions in structuring arboreal wildlife populations. Where habitat modification by megaherbivores facilitates co-occurring species, fire may amplify these effects in the short term by increasing the frequency or intensity of herbivory, leading to synergy. In the longer term, tree mortality due to both top kill by fire and toppling by large herbivores may reduce overall microhabitat availability, eliminating the synergy.
Data from: Loss of animal seed dispersal increases extinction risk in a tropical tree species due to pervasive negative density dependence across life stages
Overhunting in tropical forests reduces populations of vertebrate seed dispersers. If reduced seed dispersal has a negative impact on tree population viability, overhunting could lead to altered forest structure and dynamics, including decreased biodiversity. However, empirical data showing decreased animal-dispersed tree abundance in overhunted forests contradict demographic models which predict minimal sensitivity of tree population growth rate to early life stages. One resolution to this discrepancy is that seed dispersal determines spatial aggregation, which could have demographic consequences for all life stages. We tested the impact of dispersal loss on population viability of a tropical tree species, Miliusa horsfieldii, currently dispersed by an intact community of large mammals in a Thai forest. We evaluated the effect of spatial aggregation for all tree life stages, from seeds to adult trees, and constructed simulation models to compare population viability with and without animal-mediated seed dispersal. In simulated populations, disperser loss increased spatial aggregation by fourfold, leading to increased negative density dependence across the life cycle and a 10-fold increase in the probability of extinction. Given that the majority of tree species in tropical forests are animal-dispersed, overhunting will potentially result in forests that are fundamentally different from those existing now.
Data from: Plasticity of animal genome architecture unmasked by rapid evolution of a pelagic tunicate
Genomes of animals as different as sponges and humans show conservation of global architecture. Here we show that multiple genomic features including transposon diversity, developmental gene repertoire, physical gene order, and intron-exon organization are shattered in the tunicate Oikopleura, belonging to the sister group of vertebrates and retaining chordate morphology. Ancestral architecture of animal genomes can be deeply modified and may therefore be largely nonadaptive. This rapidly evolving animal lineage thus offers unique perspectives on the level of genome plasticity. It also illuminates issues as fundamental as the mechanisms of intron gain.
Data from: A redescription of the leggiest animal, the millipede Illacme plenipes, with notes on its natural history and biogeography (Diplopoda, Siphonophorida, Siphonorhinidae)
With up to 750 legs, the millipede Illacme plenipes Cook and Loomis, 1928 is the leggiest animal known on Earth. It is endemic to the northwestern foothills of the Gabilan Range in San Benito County, California, where it is the only known species of the family Siphonorhinidae in the Western Hemisphere. Illacme plenipes is only known from 3 localities in a 4.5 km2 area; the 1926 holotype locality is uncertain. Individuals of the species are strictly associated with large arkose sandstone boulders, and are extremely rare, with only 18 specimens known to exist in natural history collections. In contrast with its small size and unassuming outward appearance, the microanatomy of the species is strikingly complex. Here we provide a detailed redescription of the species, natural history notes, DNA barcodes for I. plenipes and similar-looking species, and a predictive occurrence map of the species inferred using niche based distribution modeling. Based on functional morphology of related species, the extreme number of legs is hypothesized to be associated with a life spent burrowing deep underground, and clinging to the surface of sandstone boulders.
Data from: Animals alter precipitation legacies: trophic and ecosystem engineering effects on plant community temporal dynamics
1. Multi-year precipitation 'legacies' can have stronger effects on plant community composition than rainfall in the current growing season, but variation in the magnitude of these effects is not fully understood. Direct interactions between plants and animals, such as herbivory, and indirect interactions, such as ecosystem engineering (via changes in the physical environment), may influence precipitation legacies by altering mechanisms of lagged effects. However, the role of direct and indirect plant-animal interactions in determining the strength of precipitation legacies remains largely unexplored. 2. Here, we investigated effects of current growing season rainfall and precipitation legacies on grassland composition, and the influence of herbivory and ecosystem engineering interactions on these temporal dynamics. From 2009 to 2014, a period spanning high and low rainfall, we recorded plant cover in kangaroo rat exclosures and paired control plots that included both burrow and inter-burrow areas. We used linear mixed effects modeling and analysis of community dissimilarities to evaluate plant composition responses to current and previous growing season rainfall and kangaroo rat herbivory (presence of seed foraging) and ecosystem engineering (burrowing). 3. We found that community composition was more strongly affected by precipitation legacies than by current growing season rainfall. Greater precipitation in the previous growing season enhanced grass cover and reduced forb and legume cover. Kangaroo rat trophic and engineering interactions had counteracting effects on these legacies. While burrowing increased grass cover and thereby amplified the effects of previous growing season rainfall on community composition, legacies were suppressed by the presence of kangaroo rat foraging, which decreased grass cover. Further analysis revealed that kangaroo rat foraging and burrowing had conflicting effects on residual plant biomass prior to the growing season, suggesting that precipitation legacies were influenced by altered litter dynamics. 4. Synthesis. Our study demonstrates that animals can impact the strength of precipitation legacies through direct and indirect interactions with the plant species that drive lag effects. The influence of multiple types of plant-animal interactions on precipitation legacies may be important to consider for ecosystem management and when generating predictions of community composition and productivity in future ecosystems.
Data from: Crossing phenotype heritability and candidate gene expression in grafted black-lipped pearl oyster Pinctada margaritifera, an animal chimera
Grafting mantle tissue of a donor pearl oyster into the gonad of a recipient oyster results in the formation of a chimera, the pearl sac. The phenotypic variations of this chimera are hypothesized to be the result of interactions between the donor and recipient genomes. In this study, the heritability of phenotypic variation and its association with gene expression were investigated for the first time during P. margaritifera pearl production. Genetic variance was evaluated at different levels, 1) before the graft operation (expression in graft tissue), 2) after grafting (pearl sac tissue expression in chimera) and 3) on the product of the graft (pearl phenotype traits) based on controlled bi-parental crosses and the F1 generation. Donor related genetic parameter estimates clearly demonstrate heritability for nacre weight and thickness, darkness and colour, surface defects and grade, which signifies a genetic basis in the donor oyster. In graft relative gene expression, the value of heritability was superior to 0.20 in for almost all genes, while in pearl sac, heritability estimates were low (h² < 0.10) (except for CALC1 and Aspein). Pearl sac expression seems to be more influenced by residual variance than the graft, which can be explained by environmental effects that influence pearls sac gene expression and act as a recipient additive genetic component. The interactions between donor and recipient are very complex and further research is required to understand the role of the recipient oysters on pearl phenotypic and gene expression variances.
Data from: Are 2D space-use analyses adapted to animals living in 3D environments? A case study on a fish shoal
Methodologies enabling the monitoring of animal movement and behavior in 3-dimensions (3D; x, y, z, the latter accounting for the vertical dimension) are becoming increasingly accessible and can be deployed on entire groups of animals inhabiting 3D habitats. When 2-dimensional (2D; x, y) space-use analyses are used on such groups, their spatial organization is represented as a planar projection of individuals' space-use. Movement on the vertical dimension is ignored and could biased ecological inference made from the spatial structure of the group. We used a digital imaging technique to track movements and feeding behavior of individual animals within a free-range aggregation of juvenile drift-feeding fish (Galaxias anomalus) in 3D and at fine spatiotemporal scales. We estimated spatiotemporal overlap of space-use and feeding territories between group-members using 2D (x, y) and 3D spatial analysis to: (1) describe the spatial structure of the group, (2) identify patterns of resource partitioning, and (3) investigate the relationship between space-use overlap and feeding behavior. We found that overlapping ratios of space-use and feeding territories were over-estimated in 2D, while 3D analysis of space-use provided evidence of spatial partitioning between group-members. We also found that, regardless of the computation used, the overlapping ratios of space-use were positively correlated with overlapping ratios of feeding territories while no effect was found on feeding activity. In conclusion, whilst 3D analysis provided valuable information on the spatial structure of a group, inferences on the ecological function of space-use can also be obtained from 2D analysis.
Data from: Energy and the scaling of animal space use
Daily animal movements are usually limited to a discrete home range area that scales allometrically with body size, suggesting that home-range size is shaped by metabolic rates and energy availability across species. However, there is little understanding of the relative importance of the various mechanisms proposed to influence home-range scaling (e.g., differences in realm productivity, thermoregulation, locomotion strategy, dimensionality, trophic guild, and prey size) and whether these extend beyond the commonly studied birds and mammals. We derive new home-range scaling relationships for fishes and reptiles and use a model-selection approach to evaluate the generality of home-range scaling mechanisms across 569 vertebrate species. We find no evidence that home-range allometry varies consistently between aquatic and terrestrial realms or thermoregulation strategies, but we find that locomotion strategy, foraging dimension, trophic guild, and prey size together explain 80% of the variation in home-range size across vertebrates when controlling for phylogeny and tracking method. Within carnivores, smaller relative prey size among gape-limited fishes contributes to shallower scaling relative to other predators. Our study reveals how simple morphological traits and prey-handling ability can profoundly influence individual space use, which underpins broader-scale patterns in the spatial ecology of vertebrates.
Data from: Novel predators reshape holozoan phylogeny and reveal the presence of a two-component signalling system in the ancestor of animals
Our understanding of the origin of animals has been transformed by characterizing their most closely related, unicellular sisters: the choanoflagellates, filastereans, and ichthyosporeans. Together with animals, these lineages make up the Holozoa [ 1, 2 ]. Many traits previously considered "animal specific" were subsequently found in other holozoans [ 3, 4 ], showing that they evolved before animals, although exactly when is currently uncertain because several key relationships remain unresolved [ 2, 5 ]. Here we report the morphology and transcriptome sequencing from three novel unicellular holozoans: Pigoraptor vietnamica and Pigoraptor chileana, which are related to filastereans, and Syssomonas multiformis, which forms a new lineage with Corallochytrium in phylogenomic analyses. All three species are predatory flagellates that feed on large eukaryotic prey, and all three also appear to exhibit complex life histories with several distinct stages, including multicellular clusters. Examination of genes associated with multicellularity in animals showed that the new filastereans contain a cell-adhesion gene repertoire similar to those of other species in this group. Syssomonas multiformis possessed a smaller complement overall but does encode genes absent from the earlier-branching ichthyosporeans. Analysis of the T-box transcription factor domain showed expansion of T-box transcription factors based on combination with a non-T-box domain (a receiver domain), which has not been described outside of vertebrates. This domain and other domains we identified in all unicellular holozoans are part of the two-component signaling system that has been lost in animals, suggesting the continued use of this system in the closest relatives of animals and emphasizing the importance of studying loss of function as well as gain in major evolutionary transitions.
Data from: UV-B radiation interacts with temperature to determine animal performance
The interaction between UV-B and temperature can modify the effects of climate variability on animal function because UV-B and increasing temperatures may increase reactive oxygen species (ROS) production and thereby impair animal performance. However, antioxidant enzyme activities are also increased at higher temperatures, which could counteract negative effects of increased ROS. Conversely, UV-B exposure at lower temperature can exacerbate the effects of ROS because of lower antioxidant enzyme activities. Phenotypes can be plastic to compensate for potentially negative environmental effects. Plasticity may be induced by conditions experienced during pre- or early post-zygotic development, and it may occur reversibly within adult organisms (acclimation). Developmental plasticity and acclimation may interact to determine phenotypes in variable environments. Here, we tested the hypothesis that increased antioxidant enzyme activities are insufficient to alleviate the interactive effects of UV-B and increased temperature on mosquitofish (Gambusia holbrooki). Additionally, we tested whether developmental conditions influenced the capacity for acclimation to UV-B and temperature so that cohorts born in summer at high UV-B and temperature conditions are better able to compensate for ROS damage compared to cohorts born in winter. We exposed mosquitofish to UV-B and control (no-UV-B) at different acclimation temperatures (18, 28 and 32 °C), and measured responses acutely at 18, 28 and 32 °C in a fully factorial design. In fish born in summer, UV-B had significant negative effects on swimming performance and resting metabolic rate at both low (18 °C) and high (32 °C) acclimation temperatures, which were accompanied by higher ROS-induced damage. At their average temperature experienced naturally (28 °C), fish born in summer were not affected by UV-B and showed lower damage and higher antioxidant enzyme activities compared to the other acclimation temperatures. In contrast, swimming performance of winter-caught fish was negatively affected by UV-B at all acclimation temperatures, which was paralleled by higher ROS-induced damage and antioxidant enzyme activities that did not acclimate. However, metabolic scope was not reduced by UV-B or temperature in any of the cohorts. Our results showed that developmental conditions modify the capacity for acclimation later in life, and that the interaction between developmental and acclimation conditions can increase the resilience of animals to environmental variability. These results have important implications for understanding the evolution of acclimation, and for predictions of how climate change affects animal performance.
Data from: Evaluation of acoustic telemetry grids for determining aquatic animal movement and survival
1. Acoustic telemetry studies have frequently prioritized linear configurations of hydrophone receivers, such as perpendicular from shorelines or across rivers, to detect the presence of tagged aquatic animals. This approach introduces unknown bias when receivers are stationed for convenience at geographic bottlenecks (e.g., at the mouth of an embayment or between islands) as opposed to deployments following a statistical sampling design. 2. We evaluated two-dimensional acoustic receiver arrays (grids: receivers spread uniformly across space) as an alternative approach to provide estimates of survival, movement, and habitat use. Performance of variably-spaced receiver grids (5–25 km spacing) was evaluated by simulating (1) animal tracks as correlated random walks (speed: 0.1–0.9 m/s; turning angle standard deviation: 5–30 degrees); (2) variable tag transmission intervals along each track (nominal delay: 15–300 seconds); and (3) probability of detection of each transmission based on logistic detection range curves (midpoint: 200–1500 m). From simulations, we quantified i) time between successive detections on any receiver (detection time), ii) time between successive detections on different receivers (transit time), and iii) distance between successive detections on different receivers (transit distance). 3. In the most restrictive detection range scenario (200 m), the 95th percentile of transit time was 3.2 days at 5 km grid spacing, 5.7 days at 7 km, and 15.2 days at 25 km; for the 1500 m detection range scenario, it was 0.1 days at 5 km, 0.5 days at 7 km, and 10.8 days at 25 km. These values represented upper bounds on the expected maximum time that an animal could go undetected. Comparison of the simulations with pilot studies on three fishes (walleye Sander vitreus, common carp Cyprinus carpio, and channel catfish Ictalurus punctatus) from two independent large lake ecosystems (lakes Erie and Winnipeg) revealed shorter detection and transit times than what simulations predicted. 4. By spreading effort uniformly across space, grids can improve understanding of fish migration over the commonly employed receiver line approach, but at increased time cost for maintaining grids.
Data from: Proxies in practice: calibration and validation of multiple indices of animal abundance
The abundance of individuals in a population is a fundamental metric in basic and applied ecology, but sampling protocols yielding precise and unbiased estimates of abundance are often cost prohibitive. Proxies of abundance are therefore common, but require calibration and validation. There are many ways to calibrate a proxy, and it is not obvious which will perform best. We use data from eight populations of Chinook salmon (Oncorhynchus tshawytscha) on the Oregon coast where multiple proxies of abundance were obtained contemporaneously with independent mark-recapture estimates. We combined multiple proxy values associated with a single level of abundance into a univariate index and then calibrated that index to mark-recapture estimates using several different techniques. We tested our calibration methods using leave-one-out cross validation and simulation. Our cross-validation analysis did not definitively identify a single best calibration technique for all populations, but we could identify consistently inferior approaches. The simulations suggested that incorporating the known mark-recapture uncertainty into the calibration technique added bias and imprecision. Cross validation techniques should be used to test multiple methods of calibrating multiple proxies to an estimate of abundance. Critical uncertainties with the application of calibrated proxies still exist, and cost-benefit analysis should be performed to help identify optimal monitoring designs.
Importance of intraspecific variation in the pollination and seed dispersal functions of a double mutualist animal species
Although most plants depend on different animals for pollination and seed dispersal, sometimes the same animal species provides both functions, being thus involved in what has been termed a 'double mutualism'. Very little is known on the effectiveness of such species as both pollinators and seed dispersers, and even less on the intraspecific level differences at the contribution of an animal mutualist to plant fitness. In this study, we focused on the interaction between a Mediterranean shrub <i>Cneorum tricoccon</i> L. (Rutaceae) and the Balearic lizard <i>Podarcis lilfordi</i> L. (Lacertidae) in order to assess: (1) the role of this lizard as a legitimate pollinator of the plant (previously thought to be exclusively insect-pollinated), and (2) the intraspecific variation in the use of flowers and fruits by lizard individuals, comparing males, females and juveniles. We further evaluated whether lizards show different fruit size selection depending on sex and age, with potential consequences for seed germination. Lizards visited more flowers and selected more hermaphrodite flowers than insects did, leading to relative increases in both fruit and seed set. Interestingly, female and juvenile lizards were the main flower visitors, whereas males were the main fruit consumers. Males selected the largest fruits (bearing the largest seeds) though this did not increase seed germination, which was only ca. 15%. We concluded that <i>P. lilfordi</i> acts as a legitimate pollinator of <i>C. tricoccon</i> and, thus, confirm that this system constitutes a new case of double mutualism, especially common in island compared to mainland systems. Moreover, our findings show a large variation among conspecific individuals in their role as either pollinators or seed dispersers, with potential implications for plant reproductive success. Our study, therefore, highlights the importance of evaluating plant-animal interactions at the intraspecific level, and calls for more in-depth studies on the consequences of such intraspecific variation.
Population asynchrony alone does not explain stability in species rich soil animal assemblages: the stabilising role of forest age on oribatid mite communities
<p>1. The importance of microbial and plant communities in the control of the diversity and structure of soil animal communities has been clarified over the last decade. Previous research focused on abiotic factors, niche separation and spatial patterns. Significant gaps still exist in our knowledge of the factors that control the stability of these communities over time.</p> <p>2. We analysed a nine-year data set form the national Long-term Ecological Research Network of Latvia. We focused on 117 oribatid species from three Scots pine forests of different age (<40 yrs, 65 yrs, and >150 yrs) and structure. For each forest type, 100 samples were collected each year, providing very high replication and long of time series for a soil community. We assessed different aspects of stability: we used a dynamic null model, parametrised on observed growth rates, to test the hypothesis that asynchrony in species populations stabilises total community size; we also analysed alpha and beta diversity over time to test the hypothesis that temporal variation in species composition and relative abundances is controlled by forest attributes.</p> <p>3. Real communities can be more stable than their stochastic counterparts if species are asynchronous, confirming for the first time the role of asynchrony in stabilising soil communities. Yet, while some real communities were more stable and had higher abundance and growth rates than others, they were not necessarily more asynchronous than the less stable communities. Species composition and relative abundances were also less variable in the more stable communities.</p> <p>4. Species asynchrony generally stabilises species rich communities but is not sufficient to explain different levels of stability between forests. Forest age is a key factor explaining different levels of overyielding and so stability. Data suggests that both asynchrony and high diversity of microhabitat structure of Scots pine forests promote stability of soil animal communities.</p>
Data from: Direct evidence that density-dependent regulation underpins the temporal stability of abundant species in a diverse animal community
To understand how ecosystems are structured and stabilized, and to identify when communities are at risk of damage or collapse, we need to know how the abundances of the taxa in the entire assemblage vary over ecologically meaningful timescales. Here, we present an analysis of species temporal variability within a single large vertebrate community. Using an exceptionally complete 33-year monthly time series following the dynamics of 81 species of fishes, we show that the most abundant species are least variable in terms of temporal biomass, because they are under density-dependent (negative feedback) regulation. At the other extreme, a relatively large number of low abundance transient species exhibit the greatest population variability. The high stability of the consistently common high abundance species—a result of density-dependence—is reflected in the observation that they consistently represent over 98% of total fish biomass. This leads to steady ecosystem nutrient and energy flux irrespective of the changes in species number and abundance among the large number of low abundance transient species. While the density-dependence of the core species ensures stability under the existing environmental regime, the pool of transient species may support long-term stability by replacing core species should environmental conditions change.
Are researchers moving away from animal models as a result of poor clinical translation in the field of stroke? an analysis of opinion papers
<p>Objectives</p> <p>Despite decades of research using animals to develop pharmaceutical treatments for stroke patients, few therapeutic options exist. The vast majority of interventions successful in preclinical animal studies have turned out to have no efficacy in humans, or to be harmful to humans. In view of this we explore whether there is evidence of a move away from animal models in this field.</p> <p>Methods</p> <p>We used an innovative methodology, the analysis of opinion papers. Although we took a systematic approach to literature searching and data extraction, this is not a systematic review because the study involves the synthesis of opinions, not research evidence. Data were extracted from retrieved papers in chronological order and analysed qualitatively and descriptively.</p> <p>Results</p> <p>Eighty eligible papers, published between 1979 and 2018, were identified. Most authors were from academic departments of neurology, neuroscience or stroke research. Authors agreed that translational stroke research was in crisis. They held diverse views about the causes of this crisis, most of which did not fundamentally challenge the use of animal models. Some, however, attributed the translational crisis to animal-human species differences and one to a lack of human in vitro models. Most of the proposed solutions involved fine-tuning animal models but authors disagreed about whether such modifications would improve translation. A minority suggested using human in vitro methods alongside animal models. One proposed focusing only on human based in vitro methods.</p> <p>Conclusion</p> <p>Despite recognising that animal models have been unsuccessful in the field of stroke, most researchers exhibited a strong resistance to relinquishing them. Nevertheless there is an emerging challenge to the use of animal models, in the form of human focused in vitro approaches. For the sake of stroke patients there is an urgent need to revitalise translational stroke research and explore the evidence for these new approaches.</p>
Data from: Sharing an environment with sick conspecifics alters odors of healthy animals
Body odors change with health status and the odors of sick animals can induce avoidance behaviors in healthy conspecifics. Exposure to sickness odors might also alter the physiology of healthy conspecifics and modify the odors they produce. We hypothesized that exposure to odors of sick (but non-infectious) animals would alter the odors of healthy cage mates. To induce sickness, we injected mice with a bacterial endotoxin, lipopolysaccharide. We used behavioral odor discrimination assays and analytical chemistry techniques followed by predictive classification modeling to ask about differences in volatile odorants produced by two types of healthy mice: those cohoused with healthy conspecifics and those cohoused with sick conspecifics. Mice trained in Y-maze behavioral assays to discriminate between the odors of healthy versus sick mice also discriminated between the odors of healthy mice cohoused with sick conspecifics and odors of healthy mice cohoused with healthy conspecifics. Chemical analyses paired with statistical modeling revealed a parallel phenomenon. Urine volatiles of healthy mice cohoused with sick partners were more likely to be classified as those of sick rather than healthy mice based on discriminant model predictions. Sickness-related odors could have cascading effects on neuroendocrine or immune responses of healthy conspecifics, and could affect individual behaviors, social dynamics, and pathogen spread.
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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.