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2,731 results for “barriers”
Data from: Testing the efficiency of nested barriers to dispersal in the Mediterranean high mountain plant Edraianthus graminifolius (Campanulaceae)
Due to strong spatial heterogeneity and limited Pleistocene glaciation, the Balkan Peninsula is a major European biodiversity hotspot. Surprisingly little, however, is known about patterns and processes of intraspecific diversification of its biota in general and of high altitude species in particular. A well-suited system to test hypotheses with respect to various isolating factors acting at different geographic scales and to explore full-range phylogeographic patterns on the Balkan Peninsula is Edraianthus graminifolius (Campanulaceae), distributed in the western Balkan mountain systems, the southwestern Carpathians and the Apennine Peninsula. To this end, we used a dense population sampling and employed Amplified Fragment Length Polymorphism (AFLP) markers and plastid DNA sequences supplemented by ecological niche modelling. The strongest splits were inferred to separate southern and northern Balkan populations from the central ones, from where range extension occurred to the Carpathians and, in more recent times, once or twice to the Apennine Peninsula. The three genetic groups in the western Balkan Peninsula were remarkably congruent among molecular markers suggesting that the barriers to gene flow acted over long time periods facilitating allopatric differentiation. Each main group of Balkan populations contained genetically and geographically distinct subgroups, which likely are the result of local refugia during warmer periods. Evidently, the topographically highly complex and during the last glacial maximum only locally glaciated Balkan Peninsula is a hotspot of species richness and endemism as well as a sanctuary of intraspecific genetic diversity, even if the underlying causes remain insufficiently understood.
Data from: Barriers to access improved water and sanitation in poor peri-urban settlements of Abidjan, Côte d'Ivoire
Achieving access to safe water and sanitation still pose major challenges in urban areas of sub-Saharan Africa countries, despite all the progress achieved in the last decade. This study assessed the ability of populations living in poor peri-urban settlements to access improved water and sanitation and identified factors influencing this access, in order to guide sustainable mitigating solutions to address associated health and environmental risks. We conducted a cross-sectional study in six poor peri-urban settlements of Yopougon, the largest municipality of Abidjan. A total of 556 randomly selected households were included. The factors associated with access to improved water and sanitation were identified through explanatory models using multivariate logistic regression. A proportion of 25% of all households assessed did not have access to clean water and 57% lacked improved sanitation. Socioeconomic status and settlement characteristics appear as the main indicators of poor access to reliable water and sanitation in peri-urban settlements. The presence of the household head's wife at home was associated with greater access to clean water (OR = 3.57; 95% CI: 1.74, 7.31), thus highlighting the important role of women in ensuring access to clean water in these specific environments. Household size, education and religion were not significantly associated with the two considered outcomes. Women therefore should be involved at all levels of programming in water promotion in these settlements to improve the population's well-being. While religion does not appear to play an important role in access to water and sanitation, successful interventions should involve religious communities because of their large representation.
Predicting barrier effects of transportation networks on Asian elephants: Implications for environmental impact assessment
<p>The rapid proliferation of transportation networks (TNs) is a threat to wide–ranged animals through habitat erosion, road–kill, and indirect socio–ecological interaction. In most cases, environmental impact assessments of TNs about animals are descriptive and targeted to direct impacts of the "linear features", while indirect and cumulative impacts are relatively neglected. Using spatially explicit data of elephant–caused damage during 2012–2015 in China, we quantified barrier effects of TN on Asian elephants and predicted the effects under a TN expansion scenario using maximum entropy algorithms. We found that TN acted as a strong barrier even for the elephants that have inhabited highly fragmented landscapes for years, with only 18% of the damage occurred on the crossed side of roads. Also, the TN expansion will reduce elephant habitats, exacerbating herd isolation and human–elephant conflict locally. Thus, we suggest that mitigation of the conflicts should be integrated into future environmental impact assessments.</p>
Data from: Oceanic barriers promote language diversification in the Japanese Islands
Good barriers make good languages. Scholars have long speculated that geographical barriers impede linguistic contact between speech communities, and promote language diversification in a manner similar to the process of allopatric speciation. This hypothesis, however, has seldom been tested systematically and quantitatively. Here we adopt methods from evolutionary biology and attempt to quantify the influence of oceanic barriers on the degree of lexical diversity in the Japanese Islands. Measuring the degree of beta diversity from basic vocabularies, we find that geographical proximity and, more importantly, isolation by surrounding ocean, independently explains a significant proportion of lexical variation across Japonic languages. Further analyses indicate that our results are neither a byproduct of using a distance matrix derived from a Bayesian language phylogeny nor an epiphenomenon of accelerated evolutionary rates in languages spoken by small communities. Moreover, we find that the effect of oceanic barriers is reproducible with the Ainu languages, indicating that our analytic approach as well as the results can be generalized beyond Japonic language family. The findings we report here are the first quantitative evidence that physical barriers formed by ocean can influence language diversification, and points to an intriguing common mechanism between linguistic and biological evolution.
Data from: Hybridization and barriers to gene flow in an island bird radiation
While reinforcement may play a role in all major modes of speciation, relatively little is known about the timescale over which species hybridize without evolving complete reproductive isolation. Birds have high potential for hybridization, and islands provide simple settings for uncovering speciation and hybridization patterns. Here we develop a phylogenetic hypothesis for a phenotypically-diverse radiation of finch-like weaver-birds (Foudia) endemic to the western Indian Ocean islands. We find that unlike Darwin's finches, each island-endemic Foudia population is a monophyletic entity for which speciation can be considered complete. In explaining the only exceptions – mismatches between taxonomy, mitochondrial and nuclear data – phylogenetic and coalescent methods support introgressive hybridization rather than incomplete lineage sorting. Human introductions of known timing of one island-endemic species, to all surrounding archipelagos provide two fortuitous experiments; (1) population sampling at known times in recent evolutionary history, (2) bringing allopatric lineages of an island radiation into secondary contact. Our results put a minimum time bound on introgression (235 years), and support hybridization between species in natural close contact (parapatry), but not between those in natural allopatry brought into contact by human introduction. Time in allopatry, rather than in sympatry, appears key in the reproductive isolation of Foudia species.
Data from: Multiple reproductive barriers separate recently diverged sunflower ecotypes
Measuring reproductive barriers between groups of organisms is an effective way to determine the traits and mechanisms that impede gene flow. However, to understand the ecological and evolutionary factors that drive speciation, it is important to distinguish between the barriers that arise early in the speciation process and those that arise after speciation is largely complete. In this paper we comprehensively test for reproductive isolation between recently diverged (< 10,000 years bp) dune and non-dune ecotypes of the prairie sunflower, Helianthus petiolaris. We find reproductive barriers acting at multiple stages of hybridization, including premating, postmating-prezygotic, and postzygotic barriers, despite the recent divergence. Barriers include extrinsic selection against immigrants and hybrids, a shift in pollinator assemblage, and post-pollination assortative mating. Together these data suggest that multiple barriers can be important for reducing gene flow in the earliest stages of speciation.
Data from: At least some meiofaunal species are not everywhere. Indication of geographic, ecological and geological barriers affecting the dispersion of species of Ototyphlonemertes (Nemertea, Hoplonemertea)
Most meiofaunal species are known to have a broad distribution with no apparent barriers to their dispersion. However, different morphological and/or molecular methods supported patterns of diversity and distribution that may be different among taxa while also conflicting within the same group. We accurately assessed the patterns of geographic distribution in actual genetic species of a marine meiofaunal animal model: Ototyphlonemertes. Specimens were collected from several sites around Europe, Northern and Central America, Southern America, Pacific Islands and Asia. We sequenced regions of two mitochondrial and two nuclear genes. Using single-gene, a concatenated data set, multilocus approaches and different DNA taxonomy methods, we disentangled the actual diversity and the spatial structures of haplotypes and tested the possible correlation between genetic diversity and geographic distance. The results show (i) the importance of using several genes to uncover both diversity and highlight phylogeographic relationships among species and that (ii) independent genetic evolutionary entities have a narrower distribution than morphological species. Moreover, (iii) a Mantel test supported a positive correlation between genetic and geographical distance. By sampling from the two sides of Isthmus of Panama, we were additionally able to identify lineage divergence times that are concordant with vicariance mechanisms caused by the geological closure of the seaway across the Isthmus. We therefore propose that in addition to distance, other geological and ecological conditions are also barriers to the dispersion of and gene flow in marine meiofaunal organisms.
Data from: Impacts and recovery from Severe Tropical Cyclone Yasi on the Great Barrier Reef
Full recovery of coral reefs from tropical cyclone (TC) damage can take decades, making cyclones a major driver of habitat condition where they occur regularly. Since 1985, 44 TCs generated gale force winds (≥17 metres/second) within the Great Barrier Reef Marine Park (GBRMP). Of the hurricane strength TCs (≥H1—Saffir Simpson scale; ≥ category 3 Australian scale), TC Yasi (February, 2011) was the largest. In the weeks after TC Yasi crossed the GBRMP, participating researchers, managers and rangers assessed the extent and severity of reef damage via 841 Reef Health and Impact Surveys at 70 reefs. Records were scaled into five damage levels representing increasingly widespread colony-level damage (1, 2, 3) and reef structural damage (4, 5). Average damage severity was significantly affected by direction (north vs south of the cyclone track), reef shelf position (mid-shelf vs outer-shelf) and habitat type. More outer-shelf reefs suffered structural damage than mid-shelf reefs within 150 km of the track. Structural damage spanned a greater latitudinal range for mid-shelf reefs than outer-shelf reefs (400 vs 300 km). Structural damage was patchily distributed at all distances, but more so as distance from the track increased. Damage extended much further from the track than during other recent intense cyclones that had smaller circulation sizes. Just over 15% (3,834 km2) of the total reef area of the GBRMP is estimated to have sustained some level of coral damage, with ~4% (949 km2) sustaining a degree of structural damage. TC Yasi likely caused the greatest loss of coral cover on the GBR in a 24-hour period since 1985. Severely impacted reefs have started to recover; coral cover increased an average of 4% between 2011 and 2013 at re-surveyed reefs. The in situ assessment of impacts described here is the largest in scale ever conducted on the Great Barrier Reef following a reef health disturbance.
Data from: Effect of oceanographic barriers and overfishing on the population genetic structure of the European spiny lobster (Palinurus elephas)
Defining population structure and genetic diversity levels is of the utmost importance for developing efficient conservation strategies. Overfishing has caused mean annual catches of the European spiny lobster (Palinurus elephas) to decrease alarmingly along its distribution area. In this context, there is a need for comprehensive studies to evaluate the genetic health of the exploited populations. The present work is based on a set of 10 nuclear markers amplified in 331 individuals from 10 different localities covering most of P. elephas distribution area. Samples from Atlantic and Mediterranean basins showed small but significant differences, indicating that P. elephas populations do not behave as a single panmictic unit but form two partially-overlapping groups. Despite intense overfishing, our dataset did not recover a recent bottleneck signal, and showed a large and stable historical effective size instead. This result could be accounted for by specific life history traits (reproduction and longevity) and the limitations of molecular markers in covering very recent timescales for non temporal samples. Our study emphasizes the necessity of integrating information on effective population sizes and life history parameters when evaluating population connectivity levels from genetic data.
Data from: Clinical Outcomes Associated with the use of the NexSite™ Hemodialysis Catheter with New Exit Barrier Technology: Results from a Prospective, Observational Multi-center Registry Study
Purpose: Decreasing the risk of catheter related bloodstream infections (CRBSIs) remains a key focus for improving outcomes and reducing cost of care for hemodialysis (HD) patients. Recent studies demonstrate CRBSI rates can be improved by managing bacterial colonization at the catheter exit site. Herein we present the results of a study documenting the clinical performance of the NexSite® HD catheter, a new tunneled central venous catheter which incorporates Exit Site Management (ESM) technology. Methods: We conducted an observational study using a prospective, multi-center registry of HD patients implanted with the NexSite® HD catheter. The primary endpoint for the study was CRBSI rate for a period up to 180-days following catheter placement. Secondary endpoints included device placement success rate, exit site healing, development of an exit site or tunnel infection, and early or late non-infectious catheter-related complications. All reasons for early non-elective catheter removal were recorded. Results: A total of 115 HD patients at 6 sites were included in the final analysis. Cumulative catheter use was 10,924 days with a mean duration of 95 days. Seven patients experienced CRBSIs during the study period resulting in a CRBSI rate of 0.64 per 1,000 catheter-days. Seventy-four patients (64.3%) had either elective catheter removal (n=56) or utilized the catheter for the entire 180-day observation period (n=18). Thirty-five patients (30%) underwent non-elective device removal either due to CRBSI (n=5), low flow (n=16), exit site issues (n=7), or for other causes (n=7). Six patients died during the observation period with 1 death due to CRBSI-associated complications and the remaining 5 deaths attributed to non-device related causes. Conclusion: Our findings demonstrate that the NexSite HD catheter equipped with ESM technology can achieve a CRBSI rate in compliance with the NKF KDOQI (National Kidney Foundation Kidney Disease Outcome Quality Initiatives) Clinical Performance Guidelines stated goal of less than 1.0/1,000 catheter-days when used in hemodialysis patients using current standard of care nursing protocols.
Data from: Topographic mapping of the interfaces between human and aquatic mosquito habitats to enable barrier-targeting of interventions against malaria vectors
Geophysical topographic metrics of local water-accumulation potential are freely available and have long been known as high resolution predictors of where aquatic habitats for immature Anopheles mosquitoes are most abundant, resulting in elevated densities of adult malaria vectors and human infection burden. Using existing entomological and epidemiological survey data, here we illustrate how topography can also be used to map out the interfaces between wet, unoccupied valleys and dry, densely populated uplands, where malaria vector densities and infection risk are focally exacerbated. These topographically identifiable geophysical boundaries experience disproportionately high vector densities and malaria transmission risk because this is where Anopheles mosquitoes first encounter humans when they search for blood after emerging or ovipositing in the valleys. Geophysical topographic indicators accounted for 67% of variance for vector density but only 43% for infection prevalence, so they could enable very selective targeting of interventions against the former but not the latter (targeting ratios of 9.0 versus 1.5 to 1, respectively). So in addition to being useful for targeting larval source management to wet valleys, geophysical topographic indicators may also be used to selectively target adult Anopheles mosquitoes with insecticidal residual sprays, fencing, vapour emanators or space sprays to barrier areas along their fringes.
Data from: Reconciling extremely strong barriers with high levels of gene exchange in annual sunflowers
In several cases, estimates of gene flow between species appears to be higher than predicted given the strength of interspecific barriers. However, as far as we are aware, detailed measurements of reproductive isolation have not previously been compared with a coalescent-based assessment of gene flow. Here, we contrast these two measures in two species of sunflower, Helianthus annuus and Helianthus petiolaris. We quantified the total reproductive barrier strength between these species by compounding the contributions of the following prezygotic and postzygotic barriers: ecogeographic isolation, reproductive asynchrony, immigrant inviability, pollen competition, hybrid seed formation, hybrid seed germination, hybrid pollen fertility, and hybrid seed set. The estimated probabilities that a reproductively successful hybrid is produced: range from 10^-4 to 10^-6 depending on the direction of the cross and the degree of independence among reproductive barriers. Population genetic estimates of gene flow estimated between these sunflower species (N_e m = 0.34-0.76) are due mainly to their large effective population sizes (N_e >10^6). The interspecific migration rate (m) is very small (<10^-7) and an order of magnitude lower than that expected based on our reproductive barrier strength estimates. Thus, even high levels of reproductive isolation (> 0.999) may produce genomic mosaics.
Data from: Hybrid speciation in sparrows I: phenotypic intermediacy, genetic admixture and barriers to gene flow
Homoploid hybrid speciation is thought to require unusual circumstances to yield reproductive isolation from the parental species, and few examples are known from nature. Here we present genetic evidence for this mode of speciation in birds. Using Bayesian assignment analyses of 751 individuals genotyped for 14 unlinked, nuclear microsatellite loci, we show that the phenotypically intermediate Italian sparrow (Passer italiae) does not form a cluster of its own, but instead exhibits clear admixture (over its entire breeding range) between its putative parental species, the house sparrow (P. domesticus) and the Spanish sparrow (P. hispaniolensis). Further, the Italian sparrow possesses mitochondrial (mt) DNA haplotypes identical to both putative parental species (although mostly of house sparrow origin), indicating a recent hybrid origin. Today, the Italian sparrow has a largely allopatric distribution on the Italian peninsula and some Mediterranean islands separated from its suggested parental species by the Alps and the Mediterranean Sea, but occurs sympatrically with the Spanish sparrow on the Gargano peninsula in southeast Italy. No evidence of interbreeding was found in this sympatric population. However, the Italian sparrow hybridizes with the house sparrow in a sparsely populated contact zone in the Alps. Yet, the contact zone is characterized by steep clines in species-specific male plumage traits, suggesting that partial reproductive isolation may also have developed between these two taxa. Thus, geographic and reproductive barriers restrict gene flow into the nascent hybrid species. We propose that an origin of hybrid species where the hybrid lineage gets geographically isolated from the parental species, as seems to have happened here, might be more common in nature than previously assumed.
Data from: Contemporary human-altered landscapes and oceanic barriers limit bumble bee gene flow
Much of the world's terrestrial landscape is being altered by humans in the form of agriculture, urbanization, and pastoral systems, with major implications for biodiversity. Bumble bees are one of the most effective pollinators in both natural and cultivated landscapes, but are often the first to be extirpated in human-altered habitats. Yet, little is known about the role of natural and human-altered habitats in promoting or limiting bumble bee gene flow. In this study, I closely examine the genetic structure of the yellow-faced bumble bee, Bombus vosnesenskii, across the south-western US coast and find strong evidence that natural oceanic barriers, as well as contemporary human-altered habitats, limit bee gene flow. Heterozygosity and allelic richness were lower in island populations, while private allelic richness was higher in island populations compared to mainland populations. Genetic differentiation, measured for three indices across the 1000km study region, was significantly greater than the null expectation (FST =0.041, F'ST=0.044, Dest=0.155) and correlated with geographic distance. Furthermore, genetic differentiation patterns were most strongly correlated with contemporary (2011) not past (2006, 2001) resistance maps calibrated for high dispersal limitation over oceans, impervious habitat, and croplands. Despite the incorporation of dramatic elevation gradients, the analyses reveal that oceans and contemporary human land use, not mountains, are the primary dispersal barriers for B. vosnesenskii gene flow. These findings reinforce the importance of maintaining corridors of suitable habitat across the distribution range of native pollinators to promote their persistence and safeguard their ability to provide essential pollination services.
Data from: A toolkit for optimizing fish passage barrier mitigation actions
The presence of dams, stream–road crossings and other infrastructure often compromises the connectivity of rivers, leading to reduced fish abundance and diversity. The assessment and mitigation of river barriers is critical to the success of restoration efforts aimed at restoring river integrity. In this study, we present a combined modelling approach involving statistical regression methods and mixed integer linear programming to maximize resident fish species richness within a catchment through targeted barrier mitigation. Compared to existing approaches, our proposed method provides enhanced biological realism while avoiding the use of complex and computationally intensive population/ecosystem models. To estimate barrier passability quickly and at low cost, we further outline a rapid barrier assessment methodology. The methodology is used to characterize potential passage barriers for various fish species common to the UK but can be readily adapted to different planning areas and other species of interest. We demonstrate the applicability of our barrier assessment and prioritization approach based on a case study of the River Wey, located in south-east England. We find that significant increases in species richness can be achieved for modest investment in barrier mitigation. In particular, dams and weirs with low passability located on mid- to high-order streams are identified as top priorities for mitigation. Synthesis and applications. Our study shows the benefits of combining a coarse resolution barrier assessment methodology with state-of-the-art optimization modelling to cost-effectively plan fish passage barrier mitigation actions. The modelling approach can help inform on-the-ground river restoration decision-making by providing a recommended course of action that best allocates limited resources in order to restore longitudinal connectivity and maximize ecological gains.
Data from: If you build it, they may not come: modifiable barriers to patient portal use among pre- and post-kidney transplant patients
Background: Patient access to health information using electronic patient portals is increasingly common. Portal use has the potential to improve patients' engagement with their health and is particularly important for patients with chronic illness; however, patients' abilities, attitudes, and use of portals is poorly understood. Methods: A single-center, cross-sectional survey was conducted of 240 consecutive pre- and post-kidney transplant patients of all levels of technological proficiency who presented to an urban transplant center in the United States. The Patient Information and Technology Assessment-Patient Portal (PITA-PP) was used to assess patients' attitudes toward the use of patient portals. Results: Most patients surveyed did not use the patient portal (n = 176, 73%). Patients were more likely to use the patient portal if they were White, highly educated, in the post-transplant period, more comfortable with technology, and reported being a frequent internet user (p < 0.05). The most common reasons for not using the patient portal included: (1) preference for traditional communication, (2) not being aware of the portal, (3) low technological proficiency, and (4) poor interoperability between the portal at the transplant center and the patient's primary care center. Conclusions: We identified several modifiable barriers to patient portal use. Some barriers can be addressed by patient education and training on portal use, and federal initiatives are underway to improve interoperability; however, a preference for traditional communications represents the most prominent barrier. Additional strategies are needed to improve portal adoption by encouraging acceptance of technologies as a way of clinical communication.
Economic and financial barriers to delivering mental health services in Georgia: Informing policy and acting on evidence
<p>Dataset includes qualitative data for the manuscript entitled "Economic and financial barriers to delivering mental health services in Georgia: Informing policy and acting on evidence".</p>
FIGURE 2 in A new species of Anoplodactylus (Arthropoda: Pycnogonida) from the Great Barrier Reef and discussion on the A. tenuicorpus - complex *
FIGURE 2. Distribution map of the species in the A. tenuicorpus complex. Records of single male and females of A. tenuicorpus are shown: Female paratype from Aliguay Island, Philippines (Child 1988b), one female from Aldabra Atoll (Child 1988a), one female from Seychelles (Child 1988a), one female from Calalan Bank off Glass Breakwater, near Magundas, Guam (Child 1991), one female from Madang, Riwa Bay, Port Moresby Bootlet Inlet (Child 1996).
FIGURE 1. Anoplodactylus perissoporus n in A new species of Anoplodactylus (Arthropoda: Pycnogonida) from the Great Barrier Reef and discussion on the A. tenuicorpus - complex *
FIGURE 1. Anoplodactylus perissoporus n. sp., from Rib Reef, Central Section of Great Barrier Reef, holotype male. A. Dorsal view (0.5mm). B. Proboscis (0.1 mm). C. Chelae (0.1 mm). D. Oviger (0.3mm). E. Third right leg (0.5mm). F. Femur of third left leg (0.5 mm). G. Distal leg articles (0.25mm). H. Distal oviger segments (details from D).
FIGURES 1–3. 1–2. Holorchis gigas n in Holorchis gigas n. sp. (Digenea: Lepocreadiidae) from the yellow-striped sweet-lips Plectorhinchus chrysotaenia (Perciformes: Haemulidae) from Lizard Island, Great Barrier Reef, with observations on Aephnidiogenes major
FIGURES 1–3. 1–2. Holorchis gigas n. sp. 1. Ventral view of holotype, uterus in bold outline. 2. Terminal genitalia, with part of ventral sucker outlined. 3. Aephnidiogenes major Yamaguti from Diagramma labiosum, Heron Island, terminal genitalia, with ovary and part of ventral sucker outlined. Scale bars: 1, 2 mm; 2, 3, 500 μm.
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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
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The International Brain Laboratory public data releases expose standardized mouse decision-making experiments, including Neuropixels recordings, widefield calcium imaging, behavior, and session metadata accessed through the ONE API.
OpenNeuro
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