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1,663 results for “BIAS”
Data from: The scale-of-choice effect and how estimates of assortative mating in the wild can be biased due to heterogeneous samples
The mode in which sexual organisms choose mates is a key evolutionary process, as it can have a profound impact on fitness and speciation. One way to study mate choice in the wild is by measuring trait correlation between mates. Positive assortative mating is inferred when individuals of a mating pair display traits that are more similar than those expected under random mating while negative assortative mating is the opposite. A recent review of 1134 trait correlations found that positive estimates of assortative mating were more frequent and larger in magnitude than negative estimates. Here we describe the scale-of-choice effect (SCE), which occurs when mate choice exists at a smaller scale than that of the investigator's sampling, while simultaneously the trait is heterogeneously distributed at the true scale-of-choice. We demonstrate the SCE by Monte Carlo simulations and estimate it in two organisms showing positive (Littorina saxatilis) and negative (L. fabalis) assortative mating. Our results show that both positive and negative estimates are biased by the SCE by different magnitudes, typically towards positive values. Therefore, the low frequency of negative assortative mating observed in the literature may be due to the SCE's impact on correlation estimates, which demands new experimental evaluation.
Data from: The search for loci under selection: trends, biases and progress
Detecting genetic variants under selection using FST outlier analysis (OA) and environmental association analyses (EAA) are popular approaches that provide insight into the genetic basis of local adaptation. Despite the frequent use of OA and EAA approaches and their increasing attractiveness for detecting signatures of selection, their application to field-based empirical data have not been synthesized. Here, we review 66 empirical studies that use Single Nucleotide Polymorphisms (SNPs) in OA and EAA. We report trends and biases across biological systems, sequencing methods, approaches, parameters, environmental variables and their influence on detecting signatures of selection. We found striking variability in both the use and reporting of environmental data and statistical parameters. For example, linkage disequilibrium among SNPs and numbers of unique SNP associations identified with EAA were rarely reported. The proportion of putatively adaptive SNPs detected varied widely among studies, and decreased with the number of SNPs analyzed. We found that genomic sampling effort had a greater impact than biological sampling effort on the proportion of identified SNPs under selection. OA identified a higher proportion of outliers when more individuals were sampled, but this was not the case for EAA. To facilitate repeatability, interpretation and synthesis of studies detecting selection, we recommend that future studies consistently report geographic coordinates, environmental data, model parameters, linkage disequilibrium, and measures of genetic structure. Identifying standards for how OA and EAA studies are designed and reported will aid future transparency and comparability of SNP-based selection studies and help to progress landscape and evolutionary genomics.
Data from: A survey of palaeontological sampling biases in fishes based on the phanerozoic record of Great Britain
Fishes represent more than half of all living vertebrate species, but patterns of fish diversity remain little explored in the fossil record. A compendium of fossil occurrences from Great Britain was assembled in order to address a series of questions concerning the palaeontological record of fishes. There are broad similarities between British richness trajectories and those compiled from global data, including an initial peak in the mid-Palaeozoic (Devonian or Carboniferous, depending on the compilation), with a late Palaeozoic trough followed by a sharp rise in diversity in the Late Cretaceous and Paleogene. The British dataset is too small to reveal any significant differences in richness between time bins using subsampling, but a modeling approach based on sampling and geological proxies consistently shows lower-than-predicted richness in the Silurian-Devonian and higher-than-predicted richness in the Late Cretaceous and Eocene. This positive excursion is robust to the exclusion of data from the early Eocene London Clay Lagerstätte. Chondrichthyans (sharks, rays, and ratfishes) and osteichthyans (ray-finned and lobe-finned fishes) show contrasting relationships with geological and sampling proxies, possibly reflecting different taphonomic profiles or idiosyncratic variation in the relative proportion of freshwater and marine deposits over the British Phanerozoic.
Data from: Introduction bias affects relationships between the characteristics of ornamental alien plants and their naturalization success
Aim: Alien plants with certain characteristics may have been introduced earlier and more frequently than others. Such introduction bias may cause spurious associations between plant characteristics and naturalization (the establishment of self-sustaining populations in the wild). We aimed to disentangle direct and indirect (i.e. mediated by introduction history) effects of species characteristics on the naturalization success of alien plants introduced for horticulture. Location: Germany (non-native range); rest of the world (native range). Methods: We compiled a dataset of 435 alien plant species introduced in cultivation in Germany, including data on their year of introduction, the number of botanical gardens where they are planted, native range, biological traits and naturalization success. We used path analysis to estimate the direct effects of geographical origin and biological traits on naturalization, and their indirect effects mediated by year and/or frequency of introduction. Results: We found significant direct positive effects of native range size and winter hardiness on naturalization. Alien species native to other parts of Europe and species with a large native range were brought to the country earlier than other species. In addition, woody species, winter-hardy species and tall species were planted more frequently than others. Because the number of botanical gardens where a species is planted increased naturalization success directly, and residence time did so indirectly through a significant positive association with the number of botanical gardens, most of the species characteristics had indirect effects on naturalization. Main conclusions: Our approach allowed us to show that apparent effects of species characteristics on naturalization success can be at least partly indirect, due to introduction biases. This indicates that failure to recognize such introduction biases could impair our ability to explain the success of alien plant species.
Data from: Behavioral vs. molecular sources of conflict between nuclear and mitochondrial DNA: the role of male-biased dispersal in a Holarctic sea duck
Genetic studies of waterfowl (Anatidae) have observed the full spectrum of mitochondrial (mt) DNA population divergence, from panmixia to deep, reciprocally monophyletic lineages. Yet these studies generally found weak or no nuclear (nu) DNA structure which was often attributed to sex-biased gene flow (i.e., male dispersal and female philopatry), a common behavior within this family. An alternative explanation for this "conflict" is that the smaller effective population size and faster sorting rate of mtDNA relative to nuDNA leads to different signals of population structure. To test these alternatives, we simulated expected nuDNA differentiation based on mtDNA patterns of effective population sizes, gene flow, and divergence times in a Holarctic pair of waterfowl subspecies, the goosander (Mergus merganser merganser) and common merganser (M. m. americanus). We compared simulated results to empirical data from 12 nuDNA introns sampled from the species' global range. Between Europe and North America, nuDNA ФST was 3.4-fold lower than mtDNA ФST, a result consistent with differences in sorting rates. However, despite geographically structured and monophyletic mtDNA lineages within continents, nuDNA ФST values were generally < 0 and significantly lower than predicted. This between- and within-continent contrast held when comparing mtDNA and nuDNA among published studies of ducks. Thus, male-mediated gene flow is a better explanation than slower sorting rates for limited nuDNA differentiation within continents, which is also supported by non-molecular data. This study illustrates the value of quantitatively testing discrepancies between mtDNA and nuDNA to reject the null hypothesis that conflict simply reflects different sorting rates.
Data from: Bunching up the background betters bias in species distribution models
Sets of presence records used to model species' distributions typically consist of observations collected opportunistically rather than systematically. As a result, sampling probability is geographically uneven, which may confound the model's characterization of the species' distribution. Modelers frequently address sampling bias by manipulating training data: either subsampling presence data or creating a similar spatial bias in non-presence background data. We tested a new method, which we call "background thickening," in the latter category. Background thickening entails concentrating background locations around presence locations in proportion to presence location density. We compared background thickening to two established sampling bias correction methods — target group background selection and presence thinning — using simulated data and data from a case study. In the case study, background thickening and presence thinning performed similarly well, both producing better model discrimination than target group background selection, and better model calibration than models without correction. In the simulation, background thickening performed better than presence thinning when the number of simulated presence locations was low, and vice versa. We discuss drawbacks to target group background selection, why background thickening and presence thinning are conservative but robust sampling bias correction methods, and why background thickening is better than presence thinning for small sample sizes. Particularly, background thickening is advantageous for treating sampling bias when data are scarce because it avoids discarding presence records.
Data from: Patterns and biases in climate change research on amphibians and reptiles: a systematic review
Climate change probably has severe impacts on animal populations, but demonstrating a causal link can be difficult because of potential influences by additional factors. Assessing global impacts of climate change effects may also be hampered by narrow taxonomic and geographical research foci. We review studies on the effects of climate change on populations of amphibians and reptiles to assess climate change effects and potential biases associated with the body of work that has been conducted within the last decade. We use data from 104 studies regarding the effect of climate on 313 species, from 464 species–study combinations. Climate change effects were reported in 65% of studies. Climate change was identified as causing population declines or range restrictions in half of the cases. The probability of identifying an effect of climate change varied among regions, taxa and research methods. Climatic effects were equally prevalent in studies exclusively investigating climate factors (more than 50% of studies) and in studies including additional factors, thus bolstering confidence in the results of studies exclusively examining effects of climate change. Our analyses reveal biases with respect to geography, taxonomy and research question, making global conclusions impossible. Additional research should focus on under-represented regions, taxa and questions. Conservation and climate policy should consider the documented harm climate change causes reptiles and amphibians.
Data from: The effect of sex-biased dispersal on opposite-sexed spatial genetic structure and inbreeding risk
Natal sex-biased dispersal has long been thought to reduce the risk of inbreeding by spatially separating opposite-sexed kin. Yet, comprehensive and quantitative evaluations of this hypothesis are lacking. In this study, we quantified the effectiveness of sex-biased dispersal as an inbreeding avoidance strategy by combining spatially explicit simulations and empirical data. We quantified the extent of kin clustering by measuring the degree of spatial autocorrelation among opposite-sexed individuals (FM structure). This allowed us to systematically explore how the extent of sex-biased dispersal, generational overlap, and mate searching distance, influenced both kin clustering, and the resulting inbreeding in the absence of complementary inbreeding avoidance strategies. Simulations revealed that when sex-biased dispersal was limited, positive FM genetic structure developed quickly and increased as the mate searching distance decreased or as generational overlap increased. Interestingly, complete long-range sex-biased dispersal did not prevent the development of FM genetic structure when generations overlapped. We found a very strong correlation between FM genetic structure and both FIS under random mating, and pedigree-based measures of inbreeding. Thus, we show that the detection of FM genetic structure can be a strong indicator of inbreeding risk. Empirical data for two species with different life history strategies yielded patterns congruent with our simulations. Our study illustrates a new application of spatial genetic autocorrelation analysis that offers a framework for quantifying the risk of inbreeding that is easily extendable to other species. Furthermore, our findings provide other researchers with a context for interpreting observed patterns of opposite-sexed spatial genetic structure.
Data from: Climate, physiological tolerance, and sex-biased dispersal shape genetic structure of Neotropical orchid bees
Understanding the impact of past climatic events on the demographic history of extant species is critical for predicting species' responses to future climate change. Paleoclimatic instability is a major mechanism of lineage diversification in taxa with low dispersal and small geographic ranges in tropical ecosystems. However, the impact of these climatic events remains questionable for the diversification of species with high levels of gene flow and large geographic distributions. In this study, we investigate the impact of Pleistocene climate change on three Neotropical orchid bee species (Eulaema bombiformis, E. meriana and E. cingulata) with transcontinental distributions and different physiological tolerances. We first generated ecological niche models to identify species-specific climatically stable areas during Pleistocene climatic oscillations. Using a combination of mitochondrial and nuclear markers, we inferred calibrated phylogenies and estimated historical demographic parameters to reconstruct the phylogeographic history of each species. Our results indicate species with narrower physiological tolerance experienced less suitable habitat during glaciations and currently exhibit strong population structure in the mitochondrial genome. However, nuclear markers with low and high mutation rates show lack of association with geography. These results combined with lower migration rate estimates from the mitochondrial than the nuclear genome suggest male-biased dispersal. We conclude that despite large effective population sizes and capacity for long-distance dispersal, climatic instability is an important mechanism of maternal lineage diversification in orchid bees. Thus, these Neotropical pollinators are susceptible to disruption of genetic connectivity in the event of large-scale climatic changes.
Data from: Improving accuracy of DNA diet estimates using food tissue control materials and an evaluation of proxies for digestion bias
Ecologists are increasingly interested in quantifying consumer diets based on food DNA in dietary samples and high-throughput sequencing of marker genes. It is tempting to assume that food DNA sequence proportions recovered from diet samples are representative of consumer's diet proportions, despite the fact that captive feeding studies do not support that assumption. Here, we examine the idea of sequencing control materials of known composition along with dietary samples in order to correct for technical biases introduced during amplicon sequencing and biological biases such as variable gene copy number. Using the Ion Torrent PGM©, we sequenced prey DNA amplified from scats of captive harbour seals (Phoca vitulina) fed a constant diet including three fish species in known proportions. Alongside, we sequenced a prey tissue mix matching the seals' diet to generate tissue correction factors (TCFs). TCFs improved the diet estimates (based on sequence proportions) for all species and reduced the average estimate error from 28 ± 15% (uncorrected) to 14 ± 9% (TCF-corrected). The experimental design also allowed us to infer the magnitude of prey-specific digestion biases and calculate digestion correction factors (DCFs). The DCFs were compared with possible proxies for differential digestion (e.g. fish protein%, fish lipid%) revealing a strong relationship between the DCFs and percent lipid of the fish prey, suggesting prey-specific corrections based on lipid content would produce accurate diet estimates in this study system. These findings demonstrate the value of parallel sequencing of food tissue mixtures in diet studies and offer new directions for future research in quantitative DNA diet analysis.
Data from: Support for a clade of Placozoa and Cnidaria in genes with minimal compositional bias
The phylogenetic placement of the morphologically simple placozoans is crucial to understanding the evolution of complex animal traits. Here, we examine the influence of adding new genomes from placozoans to a large dataset designed to study the deepest splits in the animal phylogeny. Using site-heterogeneous substitution models, we show that it is possible to obtain strong support, in both amino acid and reduced-alphabet matrices, for either a sister-group relationship between Cnidaria and Placozoa, or for Cnidaria and Bilateria as seen in most published work to date, depending on the orthologues selected to construct the matrix. We demonstrate that a majority of genes show evidence of compositional heterogeneity, and that support for the Cnidaria+Bilateria clade can be assigned to this source of systematic error. In interpreting these results, we caution against a peremptory reading of placozoans as secondarily reduced forms of little relevance to broader discussions of early animal evolution.
Data from: Phylotocol: promoting transparency and overcoming bias in phylogenetics
The integrity of science requires that the process be based on sound experimental design and objective methodology. Strategies that increase reproducibility and transparency in science protect this integrity by reducing conscious and unconscious biases. Given the large number of analysis options and the constant development of new methodologies in phylogenetics, this field is one that would particularly benefit from more transparent research design. Here, we introduce phylotocol (fī·lō·´tə·kôl), an a priori protocol-driven approach in which all analyses are planned and documented at the start of a project. The phylotocol template is simple and the implementation options are flexible to reduce administrative burdens and allow researchers to adapt it to their needs without restricting scientific creativity. While the primary goal of phylotocol is to increase transparency and accountability, it has a number of auxiliary benefits including improving study design and reproducibility, enhancing collaboration and education, and increasing the likelihood of project completion. Our goal with this Point of View article is to encourage a dialogue about transparency in phylogenetics and the best strategies to bring transparent research practices to our field.
Data from: Using risk of bias domains to identify opportunities for improvement in food- and nutrition-related research: an evaluation of research type and design, year of publication, and source of funding
Purpose: This retrospective cross-sectional study aimed to identify opportunities for improvement in food and nutrition research by examining risk of bias (ROB) domains. Methods: Rating were extracted from critical appraisal records for 5675 studies used in systematic reviews conducted by three organizations. Variables were as follows: ROB domains defined by the Cochrane Collaboration (Selection, Performance, Detection, Attrition, and Reporting), publication year, research type (intervention or observation) and specific design, funder, and overall quality rating (positive, neutral, or negative). Appraisal instrument questions were mapped to ROB domains. The kappa statistic was used to determine consistency when multiple ROB ratings were available. Binary logistic regression and multinomial logistic regression were used to predict overall quality and ROB domains. Findings: Studies represented a wide variety of research topics (clinical nutrition, food safety, dietary patterns, and dietary supplements) among 15 different research designs with a balance of intervention (49%) and observation (51%) types, published between 1930 and 2015 (64% between 2000-2009). Duplicate ratings (10%) were consistent (k=0.86-0.94). Selection and Performance domain criteria were least likely to be met (57.9% to 60.1%). Selection, Detection, and Performance ROB ratings predicted neutral or negative quality compared to positive quality (p<0.001). Funder, year, and research design were significant predictors of ROB. Some sources of funding predicted increased ROB (p<0.001) for Selection (Interventional: industry only and none/not reported; Observational: other only and none/not reported) and Reporting (Observational: university only and other only). Reduced ROB was predicted by combined and other-only funding for intervention research (p<0.005). Performance ROB domain ratings started significantly improving in 2000; others improved after 1990 (p<0.001). Research designs with higher ROB were nonrandomized intervention and time series designs compared to RCT and prospective cohort designs respectively (p<0.001). Conclusions: Opportunities for improvement in food and nutrition research are in the Selection, Performance, and Detection ROB domains.
Data from: Is biasing offspring sex ratio adaptive? a test of Fisher's principle across multiple generations of a wild mammal in a fluctuating environment
Fisher's principle explains that population sex ratio in sexually reproducing organisms is maintained at 1:1 due to negative frequency-dependent selection, such that individuals of the rare sex realize greater reproductive opportunity than individuals of the more common sex until equilibrium is reached. If biasing offspring sex ratio towards the rare sex is adaptive, individuals that do so should have a higher number of grandoffspring. In a wild population of North American red squirrels (Tamiasciurus hudsonicus) that experiences fluctuations in resource abundance and population density, we show that overall across 26 years, the secondary sex ratio was 1:1; however, stretches of years during which adult sex ratio was biased did not yield offspring sex ratios biased towards the rare sex. Females that had litters biased towards the rare sex did not have more grandoffspring. Critically, adult sex ratio was not temporally autocorrelated across years, thus the population sex ratio experienced by parents was independent of the population sex ratio experienced by their offspring by the time of their primiparity. Expected fitness benefits of biasing offspring sex ratio may be masked or negated by fluctuating environments across years, which limit the predictive value of the current sex ratio.
Data from: Sex-biased dispersal creates spatial genetic structure in a parthenogenetic ant with a dependent-lineage reproductive system
Reproduction and dispersal are key aspects of species life history that influence spatial genetic structure in populations. Several ant species in the genus Cataglyphis have evolved a unique breeding system in which new reproductives (that is, queens and males) are produced asexually by parthenogenesis; in contrast, non-reproductives (that is, workers) are produced via sexual reproduction by mates from distinct genetic lineages. We investigated how these two coexisting reproductive methods affect population-level spatial genetic structure using the ant Cataglyphis mauritanica as a model. We obtained genotypes for queens and their male mates from 338 colonies, and we found that the two lineages present in the study population occurred with equal frequency. Furthermore, analysis of spatial genetic structure revealed strong sex-biased dispersal. Because queens were produced by parthenogenesis and because they dispersed over short distances, there was an extreme level of spatial structuring: a mosaic of patches composed of clonal queens was formed. Males, on the other hand, dispersed over several hundred metres and, thus, across patches, ensuring successful interlineage mating.
Data from: Kin-bias, breeding site selection, and female fitness in a cannibalistic Neotropical frog
Resource availability influences sexual selection within populations and determines whether behaviours such as territoriality or resource sharing are adaptive. In Thoropa taophora, a frog endemic to the Atlantic Coastal Rainforest of Brazil, males compete for and defend limited breeding sites while females often share breeding sites with other females; however, sharing breeding sites may involve costs due to cannibalism by conspecific tadpoles. We studied a breeding population of T. taophora to determine (i) whether this species exhibits polygynous mating involving female choice for territorial males and limited breeding resources; (ii) whether limited breeding resources create the potential for male–male cooperation in defence of neighbouring territories; and (iii) whether females sharing breeding sites exhibit kin-biased breeding site choice, possibly driven by fitness losses due to cannibalism among offspring of females sharing sites. We used microsatellites to reconstruct parentage and quantify relatedness at eight breeding sites in our focal population, where these sites are scarce, and in a second population, where sites are abundant. We found that at localities where the appropriate sites for reproduction are spatially limited, the mating system for this species is polygynous, with typically two females sharing a breeding site with a male. We also found that females exhibit negative kin-bias in their choice of breeding sites, potentially to maximize their inclusive fitness by avoiding tadpole cannibalism of highly related kin. Our results indicate that male territorial defence and female site sharing are likely important components of this mating system, and we propose that kinship-dependent avoidance in mating strategies may be more general than previously realized.
Timbral Clarity Dumping Bias Dataset
<p>Data generated as part of research to determine the influence of 'dumping bias' on listener ratings of timbral clarity. Data comprise audio files, listening test interfaces, results and MATLAB code for plot generation.</p> <p><strong>References</strong></p> <p>AES 139 (2015): Hermes, K., Brookes, T., Hummersone, C., “The influence of dumping bias on timbral clarity ratings”, 139th Audio Engineering Society Convention, New York, USA, November 2015.</p>
FIGURE 5 in Euphilomedes chupacabra (Ostracoda: Myodocopida: Philomedidae), a new demersal marine species from coastal Puerto Rico with male-biased vespertine swimming activity
FIGURE 5. Swimming activity of male Euphilomedes chupacabra. We collected males by dragging an aquarium net through the water adjacent to a lighted pier at approximately 15 minute intervals, averaging over two net passes for each data point (see methods for further details). We fit a Gaussian distribution to the data points to estimate two parameters, maximum density (number of males) and peak activity time (minutes after sunset), for each night we collected A. Data from July 15 and fitted Gaussian model are illustrated as a representative night of collecting. Here, peak activity was estimated to be at 106 minutes after sunset and maximum density was 177 males. B. Estimates of peak activity are plotted for each night of collecting. Shaded gray area represents moon illumination phase. C. Estimates of maximum density are plotted for each night of collecting. Shaded gray area represents moon illumination phase.
FIGURE 4 in Euphilomedes chupacabra (Ostracoda: Myodocopida: Philomedidae), a new demersal marine species from coastal Puerto Rico with male-biased vespertine swimming activity
FIGURE 4. Euphilomedes chupacabra, new species, adult male paratype SBMNH # 83216; A, carapace, right, inner view; B, first antenna, left, m. v., C, second antenna, left endopod, l.v., D, copulatory limb, right, l.v. All scale bars = 0.1 mm except for that in A, which = 1 mm.
FIGURE 2 in Euphilomedes chupacabra (Ostracoda: Myodocopida: Philomedidae), a new demersal marine species from coastal Puerto Rico with male-biased vespertine swimming activity
FIGURE 2. Euphilomedes chupacabra, new species, adult female holotype SBMNH # 83215; A, mandible, right, m.v. B, maxilla, left, l.v.; C, fifth limb, left, p.v. All scale bars = 0.1 mm. Roman numerals indicate endites.
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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)
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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.