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openCustomSep 2017View details →

Locations of Uniola paniculata on selected Virginia Barrier Islands, 2017

A survey was made of the dunes of Assawoman, Northern Metompkin, Cedar, Cobb, Parramore, Hog, Wreck, Smith and Fisherman's islands and the locations of patches of Uniola paniculata were identified. No patches were found on islands for which there is no data. Inflorescence (seed head) stalks of the plants were counted from each location. Pictures were taken at some locations. Travel to the islands and logistical support was provided by the Virginia Tech Shorebird crew. Many thanks to Sarah Karpanty, Jim Fraser, Shannon Ritter, Don Fraser, Erin Heller, and the rest of that great team.

openCustomApr 2021View details →

Simulation data of barrier migration behavior and morphology from Barrier3D

Barrier3D (version 1.0) simulation results of barrier migration behavior and morphology across a range of input conditions. Simulations vary by average number of storms per year (4-12), characteristic dune growth rate (0.3-0.9 yr^-1), relative sea-level rise rate (2-8 mm/yr), level of storminess (low-high), and shoreface response rate (1,000-10,000 m^3/m/yr). Each row in the spreadsheet represents a unique model simulation; to account for storm stochasticity in the model, each unique combination of parameter values was simulated 100 times. Simulations run for 1,000 model years or until the barrier drowns. Punctuated retreat is determined to occur if the simulation includes two or more alternating periods of both transgression and relative immobility. Periods of immobility (transgression) are defined as 30 years or more of shoreline change rates (SCR) under (over) 0.5 m/yr. To test the sensitivity of these values, the statistics for punctuated retreat are calculated (for a subset of the simulations) using higher and lower duration (20-40 yrs) and SCR (0.25-0.75 m/yr) thresholds.

openCustomFeb 2022View details →

Simulation data of barrier-shrub interactions from the Barrier3D model

Barrier3D (version 1.0) simulation results of shrub expansion and barrier migration behavior and morphology across a range of input conditions. Simulations vary by the presence or absence of shrubs, the characteristic dune growth rate (0.3-0.9 yr-1), relative sea-level rise rate (3-15 mm/yr), the maximum flow reduction coefficient (0.05-0.35), and the width of initial barrier morphology. Each row in the spreadsheet represents a unique model simulation, and each simulation belongs to one of two different experiments: 1) Barrier_evolution, which is designed to assess the ways in which shrubs alter barrier morphology and the rate and style of barrier retreat by running simulations with and without shrubs across broad ranges of relative sea-level rise rates and dune growth rates; and 2) Shrub_expansion, which explores the ways in which barrier morphologic evolution influences the rate and pattern of shrub expansion. To account for storm stochasticity in the model, each unique combination of parameter values was simulated 100 times. Simulations run for 1,000 model years for the Barrier_evolution experiment, and 150 years for the Shrub_expansion experiment, or until the barrier drowns. The location of the initial cluster of shrub establishment is randomly determined in the Barrier_evolution experiment, but is constrained to the first 100 m (2%) alongshore in the Shrub_expansion experiment. Results from the two experiments are contained in two different files: barrier_island_evolution.csv and shrub_expansion.csv. A table of parameter values, definitions, and sources for the shrub module used in the experiments is given in the file: parameter_values_sources.csv

openCustomJun 1997View details →

Morphometry of Atlantic Ocean Barrier Islands, Lagoons and Marshes 1978

This data set contains morphometric measures of the lagoons of the Atlantic Coast. The goal was to obtain a measure of the complexity of the marshes that filled the lagoons behind the barrier islands. ABSTRACT The width, depth, marsh cover, and marsh-water interfaces were recorded for the lagoons along the 2000 km of coast between Long Island, New York and Miami, Florida. Eigenvectors of these variables for 134 sites (cases) were calculated and analyzed to identify the characteristic variations of these morphometric attributes. Three modes of variation account for 88% of Ihe variance of the original data: the dominant mode contrasts wide, complex lagoons and narrow, simple lagoons. The second contrasts wide, simple with narrow, complex lagoons. A third mode contrasts wide, shallow, complex with narrow, deep lagoons with few marsh-water intersects. The first mode is correlated geographically with variations in the steepness and curvature of the inner portion of the continental shelf. Using variations in the morphometric attributes of the lagoon-marsh system and the fronting islands on the ocean side, the Atlantic coast barrier islands, lagoons, and marshes are classified into three regions and eight sub-regions. The concept of barrier island ''ensembles'' along the Atlantic coast is reviewed in terms of the island-lagoon marsh system and their covariation with offshore bathymetry. The concept of these ensembles is strongly supported.

openCustomJul 2012View details →

Dune Biomass on Hog Island, Virginia Coastal Barrier Islands, 1993-2012

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opencc-by-4.0Apr 2020View details →

Trichoderma atroviride P1 Colonization of Tomato Plants Enhances Both Direct and Indirect Defense Barriers Against Insects

FIGURE 1  Survival rate of S. littoralis larvae, from 3rd instar (time 0) to pupation, reared on tomato leaves obtained from plants treated with Trichoderma atroviride P1 or untreated control plants. Asterisk indicates that the two survival curves are significantly different (LogRank test, P = 0.0027).   FIGURE 3  Survival of Macrosiphum euphorbiae reared on tomato plants treated with T. atroviride P1 or untreated control plants. Asterisk indicates that the two survival curves are significantly different (LogRank test, P = 0.0012).   FIGURE 4  Flight behavior of Aphidius ervi females (%) toward tomato plants inoculated with T. atroviride P1 and untreated controls. Asterisk indicates a significant difference, assigned by G test for independence (P < 0.001).   TABLE 1 GC-MS detection of VOCs released by tomato plants obtained from seeds untreated (Control) and treated with Trichoderma atroviride strain P1.

opencc-by-4.0Apr 2020View details →

Raw data to "Specialized pro-resolving lipid mediators are differentially altered in peripheral blood of patients with multiple sclerosis and attenuate monocyte and blood-brain barrier dysfunction"

Background: Lack of resolution of inflammation may be considered a critical player for the onset and progression of multiple sclerosis. To demonstrate this we extracted lipids from plasma samples of healthy donors and MS patients and we quantified over 65 lipid mediators (LMs) through LC-MS-MS using signature diagnostic ions via multiple reaction monitoring. Results: Out of the 65 lipid mediators analyzed, only 42 were detected and out of those only 27 were finally revealed to show differences between healthy subjects and MS patients. These 27 LMs belonged to the arachidonic (AA), docosahexaenoic (DHA) or eicosapentaenoic (EPA) acid metabolomes and we could clusterize each form of MS into a specific profile by means of principal component analysis. Altogether, compared to healthy subjects, MS patients showed a strong production of several AA-derived eicosanoids (i.e. PGE2, PGD2 and PGF2a) (Fig.1D) and a little production of two DHA-derived pro-resolving mediators (SPMs), i.e. Protectin D1 (D1) and protectin DX (PDX) (Fig.1A). However, no production of DHA-derived resolvins and maresins (Fig. 1B) as well as EPA-derived resolvins (Fig.1 C) was observed. When stratifying MS patients according to disease form, both relapsing MS patients showed production of only two pro-resolving mediators (SPMs), i.e. Resolvin D1 (RvD1) and Protectin D1 (D1) compared to healthy subjects, whereas remitting MS patients showed a production of only few AA- and DHA-derived metabolic pathway markers and progressive MS patients a strong production of several eicosanoids as well as other metabolic pathway markers. Conclusions: These data suggest that along disease progression, there is a lack of production of anti-inflammatory and pro-resolving lipid mediators associated to a higher production of pro-inflammatory ones.

opencc-zeroJul 2020View details →

Data from: Testing main Amazonian rivers as barriers across time and space within widespread taxa

Aim: Present Amazonian diversity patterns can result from many different mechanisms and, consequently, the factors contributing to divergence across regions and/or taxa may differ. Nevertheless, the river-barrier hypothesis (RBH) is still widely invoked as a causal process in divergence of Amazonian species. Here we use model-based phylogeographic analyses to test the extent to which major Amazonian rivers act similarly as barriers across time and space in two broadly distributed Amazonian taxa. Local: Amazon rainforest. Taxon: The lizard Gonatodes humeralis (Sphaerodactylidae) and the tree frog Dendropsophus leucophyllatus (Hylidae). Methods: We obtained RADseq data for samples distributed across main river barriers, representing main Areas of Endemism previously proposed for the region. We conduct model-based phylogeographic and genetic differentiation analyses across each population pair. Results: Measures of genetic differentiation (based on FST calculated from genomic data) show that all rivers are associated with significant genetic differentiation. Parameters estimated under investigated divergence models showed that divergence times for populations separated by each of the 11 bordering rivers were all fairly recent. The degree of differentiation consistently varied between taxa and among rivers, which is not an artifact of any corresponding difference in the genetic diversities of the respective taxa, or to amounts of migration based on analyses of the site-frequency-spectrum. Main conclusions: Taken together, our results support a dispersal (rather than vicariance) history, without strong evidence of congruence between these species and rivers. However, once a species crossed a river, populations separated by each and every river have remained isolated – in this sense, rivers act similarly as barriers to any further gene flow. This result suggests differing degrees of persistence and gives rise to the seeming contradiction that the divergence process indeed varies across time, space, and species, even though major Amazonian rivers have acted as secondary barriers to gene flow in the focal taxa.

opencc-zeroDec 2017View details →

Data from: Blue Carbon stocks of Great Barrier Reef deep-water seagrasses

Shallow-water seagrasses capture and store globally-significant quantities of organic carbon (OC), often referred to as 'Blue Carbon'; however, data is lacking on the importance of deep-water (>15 m) seagrasses as Blue Carbon sinks. We compared OC stocks from deep-, mid- and shallow-water seagrasses at Lizard Island within the Great Barrier Reef Lagoon. We found deep-water seagrasses (Halophila species) contained similar levels of OC as shallow-water species (e.g Halodule uninervis) (0.64 ± 0.08% and 0.9 ± 0.1 mg C cm3, 0.87 ± 0.19% and 1.3 ± 0.3 mg C cm3, respectively), despite being much sparser and smaller in stature. Deep-water seagrasses sediments contained significantly higher levels (~9-fold) of OC than surrounding bare areas. Inorganic carbon (CaCO3) levels were relatively high in deep-water seagrass sediments (8.2 ± 0.4%), and if precipitated from epiphytes within the meadow, could offset the potential CO2-sink capacity of these meadows. The δ13C signatures of sediment samples varied among depths and habitats (-10.9 and -17.0), reflecting contributions from autochthonous and allochthonous sources. If the OC stocks reported in this study are similar to deep-water Halophila meadows elsewhere within the GBR lagoon (total area 31,000 km2), then OC bound within this system is roughly estimated at 27.4 million tonnes. The dataset published in Dryad Digital Repository (<a href="http://dx.doi.org/10.5061/dryad.kj239">doi:10.5061/dryad.kj239</a>), has been updated with the corrected data values for mg Corg cm−3.

opencc-zeroAug 2020View details →

Evolution of putative barrier loci at an intermediate stage of speciation with gene flow in campions (Silene)

Understanding the origin of new species is a central goal in evolutionary biology. Diverging lineages often evolve highly heterogeneous patterns of genetic differentiation; however, the underlying mechanisms are not well understood. We investigated evolutionary processes governing genetic differentiation between the hybridizing campions Silene dioica (L.) Clairv. and S. latifolia Poiret. Demographic modeling indicated that the two species diverged with gene flow. The best-supported scenario with heterogeneity in both migration rate and effective population size suggested that a small proportion of the loci evolved without gene flow. Differentiation (FST) and sequence divergence (dXY) were correlated and both tended to peak in the middle of most linkage groups, consistent with reduced gene flow at highly differentiated loci. Highly differentiated loci further exhibited signatures of selection. In between-species population pairs, isolation by distance was stronger for genomic regions with low between-species differentiation than for highly differentiated regions that may contain barrier loci. Moreover, differentiation landscapes within and between species were only weakly correlated suggesting that linked selection due to shared recombination and gene density landscapes is not the dominant determinant of genetic differentiation in these lineages. Instead, our results suggest that divergent selection shaped the genomic landscape of differentiation between the two Silene species, consistent with predictions for speciation in the face of gene flow.

opencc-zeroAug 2020View details →

Strength in numbers? Cytotype frequency mediates effect of reproductive barriers in mixed-ploidy arrays.

When differentiated lineages come into contact, their fates depend on demographic and reproductive factors. These factors have been well-studied in taxa of the same ploidy, but less is known about sympatric lineages that differ in ploidy, particularly with respect to demographic factors. We assessed prezygotic, postzygotic, and total reproductive isolation in naturally-pollinated arrays of diploid-tetraploid and tetraploid-hexaploid population mixes of Campanula rotundifolia by measuring pollinator transitions, seed yield, germination rate, and proportion of hybrid offspring. Four frequencies of each cytotype were tested, and pollinators consistently overvisited rare cytotypes. Seed yield and F1 hybrid production were greater in 4X-6X arrays than 2X-4X arrays, while germination rates were similar, creating two distinct patterns of reproductive isolation. In 2X-4X arrays, postzygotic isolation was near-complete (3% hybrid offspring), and prezygotic isolation associated with pollinator preference is expected to facilitate the persistence of minority cytotypes. However, in 4X-6X arrays where postzygotic isolation permitted hybrid formation (44% hybrids), pollinator behavior drove patterns of reproductive isolation, with rare cytotypes being more isolated and greater gene flow expected from rare into common cytotypes. In polyploid complexes, both the specific cytotypes in contact and local cytotype frequency, likely reflecting spatial demography, will influence likelihood of gene exchange.

opencc-zeroAug 2020View details →

Breaking ecological barriers: anthropogenic disturbance leads to habitat transitions, hybridization, and high genetic diversity

Genetic diversity is expected to erode in disturbed habitats through strong selection, local extinctions, and recolonization associated with genetic bottlenecks and restricted gene flow. Despite this general prediction and over three decades of population genetics studies, our understanding of the long-term effect of environmental disturbance on local and regional genetic diversity remains limited. We conducted a population genetic survey of the microcrustacean Daphnia across a landscape subject to anthropogenic stressors from a century of industrial mining. At the local scale we found moderate genetic diversity (i.e., low clonal diversity), characteristic of habitat-specific selective sweeps and local extinctions, but high diversity and strong genetic structure at the regional scale despite the shared watershed of many lakes and exceptional dispersal ability of daphniids. Many habitats experienced changes in species assemblages, with the obligate asexual Daphnia pulex lineages—known only to inhabit ponds—dominating disrupted urban lakes. This habitat transition (pond to lake) was likely facilitated by the disruption of ecological barriers maintaining the genomic separation of these young species. Thus, disrupted habitats can exhibit complex and unexpected genetic patterns of local extinctions and recolonizations, followed by habitat transitions, hybridization and potential speciation events that are difficult to predict and should not be underestimated.

opencc-zeroJan 2020View details →

Data from: Barrier bednets target malaria vectors and expand the range of usable insecticides

Transmission of Plasmodium falciparum malaria parasites occurs when nocturnal Anopheles mosquito vectors feed on human blood. In Africa, where malaria burden is greatest, bednets treated with pyrethroid insecticide were highly effective in preventing mosquito bites and reducing transmission, and essential to achieving unprecedented reductions in malaria until 2015. Since then, progress has stalled and with insecticidal bednets losing efficacy against pyrethroid-resistant Anopheles vectors, methods that restore performance are urgently needed to eliminate any risk of malaria returning to the levels seen prior to their widespread use throughout sub-Saharan Africa. Here we show that the primary malaria vector Anopheles gambiae is targeted and killed by small insecticidal net barriers positioned above a standard bednet, in a spatial region of high mosquito activity but zero contact with sleepers, opening the way for deploying many more insecticides on bednets than currently possible. Tested against wild pyrethroid-resistant Anopheles gambiae in Burkina Faso, pyrethroid bednets with organophosphate barriers achieved significantly higher killing rates than bednets alone. Treated barriers on untreated bednets were equally effective, without significant loss of personal protection. Mathematical modelling of transmission dynamics predicted reductions in clinical malaria incidence with barrier bednets that exceeded those of 'next-generation' nets recommended by WHO against resistant vectors. Mathematical models of mosquito-barrier interactions identified alternative barrier designs to increase performance. Barrier bednets that overcome insecticide resistance are feasible using existing insecticides and production technology, and early implementation of affordable vector control tools is a realistic prospect.

opencc-zeroOct 2020View details →

Genetic structures across a biogeographical barrier reflect dispersal potential of four Southeast Asian mangrove plant species

Aim Biogeographic barriers restrict the movement of individuals, resulting in population divergence, genetic differentiation, endemism and speciation. Yet, some barriers demonstrate unequal effect across species depending on species dispersal, which manifests in varying genetic structure. We test the hypotheses that the genetic structure of four coastal mangrove species would reflect differences in dispersal potential across the Malay Peninsula, a major biogeographic barrier in the Indo-West Pacific region. Location Twelve sites from the east and west coasts of the Malay Peninsula. Taxon Mangrove trees Avicennia alba, Sonneratia alba, Bruguiera gymnorhiza, and Rhizhophora mucronata. Methods For each species, we characterized genetic structure and gene flow using seven to 12 species-specific nuclear microsatellite markers. We tested for east-west genetic differentiation across the peninsula, a stepping-stone migration pattern, and assessed the proportion of recent dispersal and direction of historical migration along the Malacca Strait. Results Significant east-west genetic differentiation across the peninsula was observed in A. alba, S. alba and B. gymnorhiza, and the effect was most pronounced for the two species with lower dispersal potential (A. alba, S. alba). In contrast, the two species with higher dispersal potential (B. gymnorhiza and R. mucronata) exhibited much higher proportion of recent inter-population migration along the Malacca Strait. The signature of historical colonization from refugia in the Andaman Sea (north-to-south migration along the Malacca Strait) predominated for A. alba and S. alba. Historical south-north migration predominated for R. mucronata and B. gymnorhiza. Main conclusions This study is the first to implicate dispersal potential as a causal factor of varying mangrove species genetic structure across a biogeographic barrier. The Malay Peninsula functions as a filter to gene flow rather than a barrier. The genetic structure in mangrove species with a higher dispersal potential is more congruent with contemporary gene flow while that of species with a lower dispersal potential reflects historical processes.Our findings hint at the role of dispersal potential as a predictor of gene flow in mangroves.

opencc-zeroSep 2020View details →

Evolution of multiple postzygotic barriers between species of the Mimulus tilingii complex

Species are often defined by their ability to interbreed (i.e., Biological Species Concept), but determining how and why reproductive isolation arises between new species can be challenging. In the Mimulus tilingii species complex, three species (M. caespitosa, M. minor, and M. tilingii) are largely allopatric and grow exclusively at high elevations (>2000m). The extent to which geographic separation has shaped patterns of divergence among the species is not well understood. In this study, we determined that the three species are morphologically and genetically distinct, yet recently diverged. Additionally, we performed reciprocal crosses within and between the species and identified several strong postzygotic reproductive barriers, including hybrid seed inviability, F1 hybrid necrosis, and F1 hybrid male and female sterility. In this study, such postzygotic barriers are so strong that a cross between any species pair in the M. tilingii complex would cause nearly complete reproductive isolation. We consider how geographical and topographical patterns may have facilitated the evolution of several postzygotic barriers and contributed to speciation of closely related members within the M. tilingii species complex.

opencc-zeroOct 2020View details →

Migratory divides coincide with reproductive barriers across replicated avian hybrid zones above the Tibetan Plateau

Migratory divides are proposed to be catalysts for speciation across a diversity of taxa. However, it is difficult to test the relative contributions of migratory behavior vs. other divergent traits to reproductive isolation. Comparing hybrid zones with and without migratory divides offers a rare opportunity to directly examine the contribution of divergent migratory behavior to reproductive barriers. We show that across replicate sampling transects of two pairs of barn swallow (Hirundo rustica) subspecies, strong reproductive isolation coincided with a migratory divide spanning 20 degrees of latitude. A third subspecies pair exhibited no evidence for a migratory divide and hybridized extensively. Within migratory divides, overwintering habitats were associated with assortative mating, implicating a central contribution of divergent migratory behavior to reproductive barriers. The remarkable geographic coincidence between migratory divides and genetic breaks supports a longstanding hypothesis that the Tibetan Plateau is a substantial barrier contributing to the diversity of Siberian avifauna.

opencc-by-4.0Sep 2020View details →

Melt Focusing Along Permeability Barriers at Subduction Zones and the Location of Volcanic Arcs: Numerical models

The dataset includes 2-D subduction zone models calculated by Comsol Mutiphysics®, slab geometry, subduction parameters, and the prediction results. Each numerical model solves the thermal structure of 31 subduction zones. The 2-D slab geometry of each subduction zone is obtained from the compilations of global subduction geometries based on earthquake catalogs Slab 1.0 and Slab2 (Hayes et al., 2012; 2018). Each slab geometry is imported in the corresponding Comsol model as a text file format. Below the point where the slab depth data is unavailable, the slab interface is simply defined as a straight line with the same dip to the bottom of the computation domain. The subduction parameters used in the models are available in Table 1. Using the calculated thermal structure at 30 Ma, we approximate the locations of the arc as the apices of 5 isotherms at 100°C interval within 800°C – 1200°C. The predicted arc locations from each isotherm are reported in Table 2 as the horizontal distance from the trench. The actual arc location in each model is defined as the point on the surface where the slab interface reaches the subarc slab depth H in Table 1 and reported as the horizontal distance from the trench in Table 2. The slab water loss depth and rate obtained from van Keken et al. (2011) are presented in Table 2. In case of the maximum temperature above the water loss depth is higher than the experimentally-derived melting condition, 800°C, we report the horizontal distance from the trench. The width of the horizontal distance of slab water loss depth is assumed as the expected melting region.

opencc-zeroNov 2020View details →

Breaking a species barrier by enabling hybrid recombination

Hybrid sterility maintains reproductive isolation between species by preventing them from exchanging genetic material. Anti-recombination can contribute to hybrid sterility when different species' chromosome sequences are too diverged to cross-over efficiently during hybrid meiosis, resulting in chromosome mis-segregation and aneuploidy. The genome sequences of the yeasts Saccharomyces cerevisiae and Saccharomyces paradoxus have diverged by about 12% and their hybrids are sexually sterile: nearly all of their gametes are aneuploid and inviable. Previous methods to increase hybrid yeast fertility have targetted the anti-recombination machinery, enhancing meiotic crossing over but also having counteracting detrimental effects on gamete viability due to increased mutagenesis and ectopic recombination. Therefore the role of anti-recombination has not been fully revealed, and it is often dismissed as a minor player in speciation. By repressing two genes, SGS1 and MSH2, specifically during meiosis, whilst maintaining their mitotic expression we were able to increase hybrid fertility 70-fold, to the level of non-hybrid crosses, confirming that anti-recombination is the principal cause of hybrid sterility. Breaking this species barrier allows us to generate, for the first time, viable euploid gametes containing recombinant hybrid genomes from these two highly diverged parent species.

opencc-by-4.0Jan 2021View details →

Exact Spin-Boson-Model Tunneling Dynamics with Time Dependent Variation Matrix Product States (TDVMPS). Barrier height and temperature parameter space

Spin-Boson tunnelling data acquired using the T-TEDOA method for Time-Dependent-Variational-Matrix-Product-States (TDVMPS) accompanying the paper <a href="https://doi.org/10.3389/fchem.2020.600731">https://doi.org/10.3389/fchem.2020.600731</a>.