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1,474 results for “reliability”
Data from: Exaggerated sexual swellings and male mate choice in primates: testing the reliable indicator hypothesis in the Amboseli baboons
The paradigm of competitive males vying to influence female mate choice has been repeatedly upheld, but, increasingly, studies also report competitive females and choosy males. One female trait that is commonly proposed to influence male mate choice is the exaggerated sexual swelling displayed by females of many Old World primate species. The reliable indicator hypothesis posits that females use the exaggerated swellings to compete for access to mates, and that the swellings advertise variation in female fitness. We tested the two main predictions of this hypothesis in a wild population of baboons (Papio cynocephalus). First, we examined the effect of swelling size on the probability of mate guarding ('consortship') by the highest-ranking male and the behaviour of those males that trailed consortships ('follower males'). Second, we asked whether a female's swelling size predicted several fitness measures. We found that high-ranking males did not prefer females with larger swellings (when controlling for cycle number and conception) and that females with larger swellings did not have higher reproductive success. Our study, the only complete test of the reliable indicator hypothesis in a primate population, rejects the idea that female baboons compete for mates by advertising heritable fitness differences. Furthermore, we found unambiguous evidence that males biased their mating decisions in favour of females who had experienced more sexual cycles since their most recent pregnancy. Thus, rather than tracking the potential differences in fitness between females, male baboons appear to track and target the potential for a given reproductive opportunity to result in fertilization.
Data from: Of 11 candidate steroids, corticosterone concentration standardized for mass is the most reliable steroid-biomarker of nutritional stress across different feather types
<p>1. Measuring corticosterone in feathers has become an informative tool in avian ecology, enabling researchers to investigate carry-over effects and responses to environmental variability. Few studies have, however, explored whether corticosterone is the only hormone expressed in feathers, and is the most indicative of environmental stress. Essential questions remain as to how to compare hormone concentrations across different types of feathers and whether preening adds steroids, applied after feather growth. 2. We used liquid chromatography coupled to tandem mass spectrometry to quantify a suite of 11 steroid hormones in back, breast, tail, and primary feathers naturally grown at overlapping time intervals by rhinoceros auklet Cerorhinca monocerata captive-reared fledglings and wild-caught juveniles. The captive-reared birds were raised on either a restricted or control diet. Measured steroids included intermediates in the adrenal steroidogenesis pathway to glucocorticoids and the sex steroids pathway to androgens and estrogens. 3. Corticosterone was detected in the majority of feathers of each type. We also detected cortisone in back feathers, androstenedione in breast feathers, and testosterone in primary feathers. Captive fledglings raised on a restricted diet had higher concentrations of corticosterone in all four feather types than captive fledglings raised on a control diet. Corticosterone concentrations were reliably repeatable across feather types when standardized for feather mass, but not for feather length. Of the seven hormones looked for in uropygial gland secretions, only corticosterone was detected in one out of 23 samples. 4. We conclude that corticosterone is the best feather-steroid biomarker for detection of developmental nutritional stress, as it was the only hormone to manifest a signal of nutritional stress, and that exposure to stress can be compared among different feather types when corticosterone concentrations are standardized by feather mass.</p>
Data from: Sepsis surveillance: an examination of parameter sensitivity and alert reliability
Objective: To examine performance of a sepsis surveillance system in a simulated environment where modifications to parameters and settings for identification of at-risk patients can be explored in-depth. Materials and Methods: This was a multiple center observational cohort study. The study population comprised 14 917 adults hospitalized in 2016. An expert-driven rules algorithm was applied against 15.1 million data points to simulate a system with binary notification of sepsis events. Three system scenarios were examined: a scenario as derived from the second version of the Consensus Definitions for Sepsis and Septic Shock (SEP-2), the same scenario but without systolic blood pressure (SBP) decrease criteria (near SEP-2), and a conservative scenario with limited parameters. Patients identified by scenarios as being at-risk for sepsis were assessed for suspected infection. Multivariate binary logistic regression models estimated mortality risk among patients with suspected infection. Results: First, the SEP-2-based scenario had a hyperactive, unreliable parameter SBP decrease >40 mm Hg from baseline. Second, the near SEP-2 scenario demonstrated adequate reliability and sensitivity. Third, the conservative scenario had modestly higher reliability, but sensitivity degraded quickly. Parameters differed in predicting mortality risk and represented a substitution effect between scenarios. Discussion: Configuration of parameters and alert criteria have implications for patient identification and predicted outcomes. Conclusion: Performance of scenarios was associated with scenario design. A single hyperactive, unreliable parameter may negatively influence adoption of the system. A trade-off between modest improvements in alert reliability corresponded to a steep decline in condition sensitivity in scenarios explored.
Data from: Reliable genotyping of the koala (Phascolarctos cinereus) using DNA isolated from a single faecal pellet
The koala, an Australian icon, has been added to the threatened species list. Rationale for the listing includes proposed declines in population size, threats to populations (e.g. disease) and loss and fragmentation of habitat. There is now an urgent need to obtain accurate data to assess the status of koala populations in Australia, to ensure the long-term viability of this species. Advances in genetic techniques have enabled DNA analysis to study and inform the management of wild populations; however, sampling of individual koalas is difficult in tall, often remote, eucalypt forest. The collection of faecal pellets (scats) from the forest floor presents an opportunistic sampling strategy, where DNA can be collected without capturing or even sighting an individual. Obtaining DNA via noninvasive sampling can be used to rapidly sample a large proportion of a population; however, DNA from noninvasively collected samples is often degraded. Factors influencing DNA quality and quantity include environmental exposure, diet and methods of sample collection, storage and DNA isolation. Reduced DNA quality and quantity can introduce genotyping errors and provide inaccurate DNA profiles, reducing confidence in the ability of such data to inform management/conservation strategies. Here, we present a protocol that produces a reliable individual koala genotype from a single faecal pellet and highlight the importance of optimizing DNA isolation and analysis for the species of interest. This method could readily be adapted for genetic studies of mammals other than koalas, particularly those whose diet contains high proportions of volatile materials that are likely to induce DNA damage.
Data from: A reliable technique to quantify the individual variability of iridescent coloration in birds
The study of iridescent coloration in birds emerged only recently, mainly due to the difficulty inherent in quantifying its directionality. Directionality restrains color perception to a limited angle and thereby causes drastic changes in brightness when an animal is in motion. Although a versatile goniometer for quantifying iridescent coloration has been developed recently, so far, it has only been applied to measuring the highly directional iridescent coloration in a hummingbird species. Thus, the reliability of the goniometer for species displaying more common and less directional iridescent coloration has yet to be evaluated. Additionally, two important methodological aspects remain to be assessed before this apparatus can be used confidently: 1) whether directionality, which could be subject to sexual selection, can be quantified in a repeatable way; and 2) whether the apparatus gives more precise and accurate measurements than a less complex traditional method. Using feathers collected from 271 male tree swallows Tachycineta bicolor over two years, we found that the goniometer provided repeatable measurements of directionality across individuals and across three body regions, namely the crown, mantle and rump. The apparatus was also more repeatable than a traditional method involving a bifurcated probe and reduced a brightness bias associated with individual differences in barbule tilt. We strongly encourage researchers to invest in this methodological change considering the multiple advantages demonstrated and to quantify the directionality of iridescent coloration as to unveil its role in signaling and sexual selection.
Data from: Input matters matter: bioclimatic consistency to map more reliable species distribution models
1. Accuracy of global bioclimatic databases is essential to understand biodiversity-environment relationships. Many studies have explored biases and uncertainties related to species distribution models (SDMs) but the effect of choosing a specific database among the different alternatives has not been previously assessed. 2. The lack of bioclimatic congruence (degree of agreement) between different databases is a main concern in distribution modelling and it is critical in single-source models, for which the database choice is decisive. In order to prevent unreliable predictions derived from distorted input data, SDMs accuracy can be assessed by mapping model predictions according to a bioclimatic congruence measure derived from the comparison of multiple databases, which can be achieved with the bioclimatic consistency maps that we propose in this study. Here, i) we present the first global-scale bioclimatic congruence map to analyse environmental mismatches between recently updated bioclimatic databases. We also test the importance of input matters on the reliability of distribution models of sixteen mammals, by addressing ii) inconsistencies among species response curves (temperature and precipitation), and iii) discrepancies among SDMs predictions depending on the chosen bioclimatic database. Finally, iv) we propose a strategy to assess bioclimatic consistency of model predictions, showing its application to the specific case of Litocranius walleri. 3. Our results confirm that the single-source modelling approach greatly influences the estimation of species-environment relationship and consequently, bias spatial predictions derived from SDMs. This is especially true for studies conducted in polar and mountainous regions which showed the smallest bioclimatic congruence. We show that by adding bioclimatic congruence to SDMs projections, we can build a bioclimatic consistency map that enables the detection of both risky and consistent areas, as revealed for the case of L. walleri. 4. Assessing uncertainty in bioclimatic input data is key to avoid erroneous conclusions in macroecological and biogeographical studies. The spatial characterisation of bioclimatic consistency provides an adequate empirical framework which effectively illustrates bioclimatic data limitations. We strongly recommend that this new strategy should be formally and systematically incorporated into distribution modelling to build more reliable SDMs, which are essential to develop successful biodiversity conservation programmes.
Data from: Relationship type affects the reliability of dispersal distance estimated using pedigree inferences in partially sampled populations: a case study involving invasive American mink in Scotland
Estimating dispersal—a key parameter for population ecology and management—is notoriously difficult. The use of pedigree assignments, aided by likelihood-based software, has become popular to estimate dispersal rate and distance. However, the partial sampling of populations may produce false assignments. Further, it is unknown how the accuracy of assignment is affected by the genealogical relationships of individuals and is reflected by software-derived assignment probabilities. Inspired by a project managing invasive American mink (Neovison vison), we estimated individual dispersal distances using inferred pairwise relationships of culled individuals. Additionally, we simulated scenarios to investigate the accuracy of pairwise inferences. Estimates of dispersal distance varied greatly when derived from different inferred pairwise relationships, with mother–offspring relationship being the shortest (average = 21 km) and the most accurate. Pairs assigned as maternal half-siblings were inaccurate, with 64%–97% falsely assigned, implying that estimates for these relationships in the wild population were unreliable. The false assignment rate was unrelated to the software-derived assignment probabilities at high dispersal rates. Assignments were more accurate when the inferred parents were older and immigrants and when dispersal rates between subpopulations were low (1% and 2%). Using 30 instead of 15 loci increased pairwise reliability, but half-sibling assignments were still inaccurate (>59% falsely assigned). The most reliable approach when using inferred pairwise relationships in polygamous species would be not to use half-sibling relationship types. Our simulation approach provides guidance for the application of pedigree inferences under partial sampling and is applicable to other systems where pedigree assignments are used for ecological inference.
Data from: Reliable effective number of breeders/adult census size ratios in seasonal-breeding species: opportunity for integrative demographic inferences based on capture-mark-recapture data and multilocus genotypes
The ratio of the effective number of breeders (Nb) to the adult census size (Na), Nb/ Na, approximates the departure from the standard capacity of a population to maintain genetic diversity in one reproductive season. This information is relevant for assessing population status, understanding evolutionary processes operating at local scales and unraveling how life-history traits affect these processes. However, our knowledge on Nb/Na ratios in nature is limited because estimation of both parameters is challenging. The sibship frequency (SF) method is adequate for reliable Nb estimation because it is based on sibship and parentage reconstruction from genetic marker data, thereby providing demographic inferences that can be compared with field-based information. In addition, capture-mark-recapture (CMR) robust design methods are well suited for Na estimation in seasonal-breeding species. We used tadpole genotypes of three pond-breeding amphibian species (Epidalea calamita, Hyla molleri and Pelophylax perezi, n = 73-96 single-cohort tadpoles / species genotyped at 15-17 microsatellite loci) and candidate parental genotypes (n = 94-300 adults / species) to estimate Nb by the SF method. To assess the reliability of Nb estimates, we compared sibship and parentage inferences with field-based information and checked for the convergence of results in replicated subsampled analyses. Finally, we used CMR data from a 6-year monitoring program to estimate annual Na in the three species and calculate the Nb/Na ratio. Reliable ratios were obtained for E. calamita (Nb/Na = 0.18-0.28) and P. perezi (0.5), but in H. molleri Na could not be estimated and genetic information proved insufficient for reliable Nb estimation. Integrative demographic studies taking full advantage of SF and CMR methods can provide accurate estimates of the Nb/Na ratio in seasonal-breeding species. Importantly, the SF method provides results that can be readily evaluated for reliability. This represents a good opportunity for obtaining robust demographic inferences with wide applications for evolutionary and conservation research.
Data from: Reliability assessment of null allele detection: inconsistencies between and within different methods
Microsatellite loci are widely used in population genetic studies, but the presence of null alleles may lead to biased results. Here, we assessed five methods that indirectly detect null alleles and found large inconsistencies among them. Our analysis was based on 20 microsatellite loci genotyped in a natural population of Microtus oeconomus sampled during 8 years, together with 1200 simulated populations without null alleles, but experiencing bottlenecks of varying duration and intensity, and 120 simulated populations with known null alleles. In the natural population, 29% of positive results were consistent between the methods in pairwise comparisons, and in the simulated data set, this proportion was 14%. The positive results were also inconsistent between different years in the natural population. In the null-allele-free simulated data set, the number of false positives increased with increased bottleneck intensity and duration. We also found a low concordance in null allele detection between the original simulated populations and their 20% random subsets. In the populations simulated to include null alleles, between 22% and 42% of true null alleles remained undetected, which highlighted that detection errors are not restricted to false positives. None of the evaluated methods clearly outperformed the others when both false-positive and false-negative rates were considered. Accepting only the positive results consistent between at least two methods should considerably reduce the false-positive rate, but this approach may increase the false-negative rate. Our study demonstrates the need for novel null allele detection methods that could be reliably applied to natural populations.
Data from: Echolocation detections and digital video surveys provide reliable estimates of the relative density of harbour porpoises
1. Robust estimates of the density or abundance of cetaceans are required to support a wide range of ecological studies and inform management decisions. Considerable effort has been put into the development of line-transect sampling techniques to obtain estimates of absolute density from aerial and boat-based visual surveys. Surveys of cetaceans using acoustic loggers or digital cameras provide alternative methods to estimate relative density that have the potential to reduce cost and provide a verifiable record of all detections. However the ability of these methods to provide reliable estimates of relative density has yet to be established. 2. These methodologies were compared by conducting aerial visual line-transect surveys (n=10 days) and digital video strip-transect surveys (n=4 days) in the Moray Firth, Scotland. Simultaneous acoustic data were collected from moored echolocation detectors (C-PODs) at 58 locations across the study site. Density surface modelling (DSM) of visual survey data was used to estimate spatial variation in relative harbour porpoise density on a 4x4 km grid. DSM was also performed on the digital survey data, and the resulting model output compared to that from visual survey data. Estimates of relative density from visual surveys around acoustic monitoring sites were compared with several metrics previously used to characterise variation in acoustic detections of echolocation clicks. 3. There was a strong correlation between estimates of relative density from visual surveys and digital video surveys (Spearman's ρ=0.85). A correction to account for animals missed on the transect line (previously calculated for visual aerial surveys of harbour porpoise in the North Sea (Hammond et al. 2013)) was used to convert relative density from the visual surveys to absolute density. This allowed calculation of the first estimate of a proxy for detection probability in digital video surveys, suggesting that 61% (CV=0.53) of harbour porpoises were detected. There was also a strong correlation between acoustic detections and density with a Spearman's ρ=0.73 for detection positive hours. 4. These results provide confidence in the emerging use of digital video and acoustic surveys for studying the density of small cetaceans and their responses to environmental and anthropogenic change.
DNA barcodes combined with multi-locus data of representative taxa can generate reliable higher-level phylogenies
<p>Taxa are frequently labeled incertae sedis when their placement is debated at ranks above the species level, such as their subgeneric, generic, or subtribal placement. This is a pervasive problem in groups with complex systematics due to difficulties in identifying suitable synapomorphies. In this study, we propose combining DNA barcodes with a multilocus backbone phylogeny in order to assign taxa to genus or other higher-level categories. This sampling strategy generates molecular matrices containing large amounts of missing data that are not distributed randomly: barcodes are sampled for all representatives, and additional markers are sampled only for a small percentage. We investigate the effects of the degree and randomness of missing data on phylogenetic accuracy using simulations for up to 100 markers in 1000-tips trees, as well as a real case: the subtribe Polyommatina (Lepidoptera: Lycaenidae), a large group including numerous species with unresolved taxonomy. Our simulation tests show that when a strategic and representative selection of species for higher-level categories has been made for multigene sequencing (approximately one per simulated genus), the addition of this multigene backbone DNA data for as few as 5–10% of the specimens in the total data set can produce high-quality phylogenies, comparable to those resulting from 100% multigene sampling. In contrast, trees based exclusively on barcodes performed poorly. This approach was applied to a 1365-specimen data set of Polyommatina (including ca. 80% of described species), with nearly 8% of representative species included in the multigene backbone and the remaining 92% included only by mitochondrial COI barcodes, a phylogeny was generated that highlighted potential misplacements, unrecognized major clades, and placement for incertae sedis taxa. We use this information to make systematic rearrangements within Polyommatina, and to describe two new genera. Finally, we propose a systematic workflow to assess higher-level taxonomy in hyperdiverse groups. This research identifies an additional, enhanced value of DNA barcodes for improvements in higher-level systematics using large data sets.</p>
Data from: Interpopulation variation in a condition-dependent signal: predation regime affects signal intensity and reliability
In many models of sexual selection, conspicuous ornaments are preferred by mates because they indicate heritable signaler viability. To function as indicators, ornaments must exhibit a proportional relationship between expression and viability. In cases where the evolutionary interests of signaler and receiver diverge, selection favors exploitative exaggeration by low-viability individuals producing unreliable signals. Theory suggests that the evolutionary stability of such communication systems requires costs that prevent low-viability males from expressing disproportionately intense signals. Therefore, given ecological variation in signaling cost, the reliability of signaling systems will vary concomitantly. In this study, we assess the effect of a variable signal cost, predation, on signal intensity and reliability among 16 populations of Bahamas mosquitofish (Gambusia hubbsi) that use colorful dorsal fins in courtship displays. We found that fin coloration was more intense in low-predation sites and could be used to predict body condition. However, this predictive relationship was apparent only in populations subject to predation risk. We demonstrate an important role for ecological signaling cost in communication and show that ecological heterogeneity drives interpopulation variation in both the intensity and the reliability of a sexual signal.
Estimating phylogenies from shape and similar multidimensional data: why it is not reliable
In recent years, there has been controversy whether multidimensional data such as geometric morphometric data or information on gene expression can be used for estimating phylogenies. This study uses simulations of evolution in multidimensional phenotype spaces to address this question and to identify specific factors that are important for answering it. Most of the simulations use phylogenies with four taxa, so that there are just three possible unrooted trees and the effect of different combinations of branch lengths can be studied systematically. In a comparison of methods, squared-change parsimony performed similarly well as maximum likelihood, and both methods outperformed Wagner and Euclidean parsimony, neighbor-joining and UPGMA. Under an evolutionary model of isotropic Brownian motion, phylogeny can be estimated reliably if dimensionality is high, even with relatively unfavorable combinations of branch lengths. By contrast, if there is phenotypic integration such that most variation is concentrated in one or a few dimensions, the reliability of phylogenetic estimates is severely reduced. Evolutionary models with stabilizing selection also produce highly unreliable estimates, which are little better than picking a phylogenetic tree at random. To examine how these results apply to phylogenies with more than four taxa, we conducted further simulations with up to eight taxa, which indicated that the effects of dimensionality and phenotypic integration extend to more than four taxa, and that convergence among internal nodes may produce additional complications specifically for greater numbers of taxa. Overall, the simulations suggest that multidimensional data, under evolutionary models that are plausible for biological data, do not produce reliable estimates of phylogeny.
Data from: Reliability of macrofossils in woodrat (Neotoma) middens for detecting low-density tree populations
Macrofossils from woodrat (Neotoma) middens serve as an important proxy for reconstructing past vegetation in arid and semiarid regions of North America. The presence/absence of plant macrofossils in middens can provide valuable information on temporal and spatial patterns of plant migration and range boundaries. The primary aim of this study was to determine how local plant abundance, distance of plant populations from midden sites, and species population density on the landscape affect the probability of occurrence of macrofossils in middens. The study was designed with the primary intent of determining the reliability of middens in detecting scattered populations of Pinus ponderosa. We analyzed macrofossil assemblages from 42 modern woodrat middens from West Carrizo Canyon in southeastern Colorado, near the current eastern range margin of Pinus ponderosa. We compared midden contents with composition of the surrounding vegetation, measuring distance from the midden to the nearest individual of selected plant species, and the percent cover of each species within 30 m of the midden. We used this information to model the probability of species presence in a midden across a range of population densities on the landscape. Macrofossils of Juniperus spp., Quercus gambelii, and Opuntia spp. were consistently found in middens regardless of their local abundance in vegetation, although populations occurred within 30 m of all middens. Pinus edulis and P. ponderosa occurred in nearly all middens within 20-30 m of individual trees. P. ponderosa was rare in middens >20-30 m away from individual trees. Results of a simple simulation model suggest that middens become absolutely reliable indicators of P. ponderosa presence on the landscape only when average tree density exceeds 50 stems ha-1. Woodrats reliably collected macrofossils of Pinus edulis, P. ponderosa, Juniperus spp., Quercus gambelii, and Opuntia spp. when populations of these taxa occur within 20-30 m of a midden site. Woodrats did not collect P. ponderosa when the nearest individuals were more than 30 m away. Low-density populations of these and other species may be difficult to detect in fossil woodrat-midden series owing to reduced probability that individuals grow within foraging distance of the middens. Data from this and similar studies can be used to construct and parameterize a forward model of macrofossil representation in woodrat middens.
Data from: Reliable, verifiable and efficient monitoring of biodiversity via metabarcoding
To manage and conserve biodiversity, one must know what is being lost, where, and why, as well as which remedies are likely to be most effective. Metabarcoding technology can characterise the species compositions of mass samples of eukaryotes or of environmental DNA. Here, we validate metabarcoding by testing it against three high-quality standard data sets that were collected in Malaysia (tropical), China (subtropical) and the United Kingdom (temperate) and that comprised 55,813 arthropod and bird specimens identified to species level with the expenditure of 2,505 person-hours of taxonomic expertise. The metabarcode and standard data sets exhibit statistically correlated alpha- and beta-diversities, and the two data sets produce similar policy conclusions for two conservation applications: restoration ecology and systematic conservation planning. Compared with standard biodiversity data sets, metabarcoded samples are taxonomically more comprehensive, many times quicker to produce, less reliant on taxonomic expertise and auditable by third parties, which is essential for dispute resolution.
Data from: Comparing direct and indirect selfing rate estimates: when are population-structure estimates reliable?
The rate of self-fertilization (that is, selfing) is a key evolutionary parameter in hermaphroditic species, yet obtaining accurate estimates of selfing rates in natural populations can be technically challenging. Most published estimates are derived from population-level heterozygote deficiency (that is, FIS) or identity disequilibria (for example, the software RMES (robust multilocus estimate of selfing)). These indirect methods can be applied to population genetic survey data, whereas direct methods using progeny arrays require much larger data sets that are often difficult to collect in natural populations or even require captive breeding. Unfortunately, indirect methods rely on assumptions that can be problematic, such as negating biparental inbreeding, inbreeding disequilibrium and (for FIS) the presence of null alleles. The performance of indirect estimates against progeny-array estimates is still largely unknown. Here we used both direct progeny-array and indirect population-level methods to estimate the selfing rate in a single natural population of the simultaneously hermaphroditic freshwater snail Radix balthica throughout its reproductive lifespan using 10 highly polymorphic microsatellites. We found that even though progeny arrays (n=1034 field-collected embryos from 60 families) did not reveal a single selfed embryo, FIS-based selfing rates (n=316 adults) were significantly positive in all 6 sequential population samples. Including a locus with a high frequency of null alleles further biased FIS-based estimates. Conversely, RMES-based estimates were very similar to progeny-array estimates and proved insensitive to null alleles. The assumptions made by RMES were thus either met or irrelevant in this particular population, making RMES a valid, cost-efficient alternative to progeny arrays.
Data from: A low-threshold potassium current enhances sparseness and reliability in a model of avian auditory cortex
Birdsong is a complex vocal communication signal, and like humans, birds need to discriminate between similar sequences of sound with different meanings. The caudal mesopallium (CM) is a cortical-level auditory area implicated in song discrimination. CM neurons respond sparsely to conspecific song and are tolerant of production variability. Intracellular recordings in CM have identified a diversity of intrinsic membrane dynamics, which could contribute to the emergence of these higher-order functional properties. We investigated this hypothesis using a novel linear-dynamical cascade model that incorporated detailed biophysical dynamics to simulate auditory responses to birdsong. Neuron models that included a low-threshold potassium current present in a subset of CM neurons showed increased selectivity and coding efficiency relative to models without this current. These results demonstrate the impact of intrinsic dynamics on sensory coding and the importance of including the biophysical characteristics of neural populations in simulation studies.
Data from: Using public surveys to reliably and rapidly estimate the distributions of multiple invasive species on the Andaman archipelago
To effectively manage multiple biological invasions, information on their distributions must be generated rapidly and over large spatial scales. Using public surveys in a false-positive occupancy framework, we reliably estimate the distributions of three synanthropic invasive species on the Andaman Islands.
Data from: The program STRUCTURE does not reliably recover the correct population structure when sampling is uneven: sub-sampling and new estimators alleviate the problem
Inferences of population structure and more precisely the identification of genetically homogeneous groups of individuals are essential to the fields of ecology, evolutionary biology, and conservation biology. Such population structure inferences are routinely investigated via the program STRUCTURE implementing a Bayesian algorithm to identify groups of individuals at Hardy-Weinberg and linkage equilibrium. While the method is performing relatively well under various population models with even sampling between subpopulations, the robustness of the method to uneven sample size between subpopulations and/or hierarchical levels of population structure has not yet been tested despite being commonly encountered in empirical datasets. In this study, I used simulated and empirical microsatellite datasets to investigate the impact of uneven sample size between subpopulations and/or hierarchical levels of population structure on the detected population structure. The results demonstrated that uneven sampling often leads to wrong inferences on hierarchical structure and downward biased estimates of the true number of subpopulations. Distinct subpopulations with reduced sampling tended to be merged together, whilst at the same time, individuals from extensively sampled subpopulations were generally split, despite belonging to the same panmictic population. Four new supervised methods to detect the number of clusters were developed and tested as part of this study and were found to outperform the existing methods using both evenly and unevenly sampled datasets. Additionally, a sub-sampling strategy aiming to reduce sampling unevenness between subpopulations is presented and tested. These results altogether demonstrate that when sampling evenness is accounted for, the detection of the correct population structure is greatly improved.
Data from: Birds land reliably on complex surfaces by adapting their foot-surface interactions upon contact
Birds land on a wide range of complex surfaces, yet it is unclear how they grasp a perch reliably. Here, we show how Pacific parrotlets exhibit stereotyped leg and wing dynamics regardless of perch diameter and texture, but foot, toe, and claw kinematics become surface-specific upon touchdown. A new dynamic grasping model, which integrates our detailed measurements, reveals how birds stabilize their grasp. They combine predictable toe pad friction with probabilistic friction from their claws, which they drag to find surface asperities—dragging further when they can squeeze less. Remarkably, parrotlet claws can undergo superfast movements, within 1–2 ms, on moderately slippery surfaces to find more secure asperities when necessary. With this strategy, they first ramp up safety margins by squeezing before relaxing their grasp. The model further shows it is advantageous to be small for stable perching when high friction relative to normal force is required because claws can find more usable surface, but this trend reverses when required friction shrinks. This explains how many animals and robots may grasp complex surfaces reliably.
ScienceDex guides
Understand access before you commit
These curated guides explain access requirements, typical timelines, costs, and reuse considerations for widely used research datasets.
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.