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Sample records for fine-scale oscillatory banding

  1. Fine-scale oscillatory banding in otoliths from arctic charr (Salveninus alpinus) and pike (Esox lucius)

    SciTech Connect

    Meldrum, A.; Halden, N.M.

    1997-12-31

    Transmission electron microscopy of otoliths from the inner ear of arctic charr and pike has revealed the presence of fine banding on the scale of several nanometers. The thickness of the bands was observed to vary in different portions of the sample, and some areas were not banded. EDS analysis could not detect chemical differences within the bands, but electron diffraction showed that the crystallographic orientation of the bands is related by a lattice mismatch. Previously, banding on the scale of 50 to 100 microns was observed by SEM in otoliths from arctic charr and was attributed to seasonal variations in growth. The fine-scale banding observed in this study, however, is unlikely to represent a daily variation. Electron diffraction from the pike samples shows that the material is composed of CaCO{sub 3} having the both the vaterite and aragonite structure, and hydrous CaCO{sub 3} was also observed. The large-scale banding previously identified by SEM was not observed in the TEM despite attempts to intersect the boundaries of the micron-sized layers. The interaction of the electron beam with the sample material was investigated by conducting several electron-irradiation experiments. The electron beam was observed to interact strongly with the sample and caused the precipitation of cubic CaO from the calcium carbonate matrix. Bright-field imaging showed the development of fine grained ({approximately} 5 nm) randomly oriented crystallites which accumulated with increasing electron dose. These initial results suggest that the precipitation of CaO is not driven by electron-beam beating. Previously, a similar phase-change phenomenon has been observed in hydroxyapatite from dental enamel. Other Ca-bearing biominerals may therefore also be expected to be sensitive to electron irradiation.

  2. Lunar banding in the scleractinian coral Montastraea faveolata: Fine-scale structure and influence of temperature

    NASA Astrophysics Data System (ADS)

    Winter, Amos; Sammarco, Paul W.

    2010-10-01

    Lunar cycles play an important role in controlling biological rhythms in many organisms, including hermatypic corals. Coral spawning is correlated with environmental factors, including surface seawater temperature (SST) and lunar phase. Calcium carbonate skeletons of corals possess minute structures that, when viewed via X-radiography, produce high-density (HD) annual banding patterns. Some corals possess dissepiments that serve as the microstructural base for upward corallite growth. Here we report the results of detailed structural analysis of the skeleton of Montastraea faveolata (Scleractinia) (Ellis and Solander, 1786) and quantify the number of dissepiments that occur between HD bands, including interannual and intercorallite variability. Using a 30 year database, spanning from 1961 to 1991, we confirm earlier speculation by several authors that the frequencies of these microbands within a year is tightly linked to the lunar cycle. We also demonstrate that the frequency distribution of the number of these dissepiments per year is skewed to lower numbers. Extensive statistical analyses of long-term daily SST records (University of Puerto Rico, Mayaguez) revealed that precipitation of dissepiments is suppressed in years of cooler-than-average seawater temperature. We propose that dissepiment deposition is driven primarily by lunar cycle and seawater temperature, particularly at lower temperatures, and banding is generally unaffected by normal or high temperatures. These fine-scale banding patterns are also strongly correlated with the number of lunar months between reproductive spawning events in average or warmer-than-average seawater temperature years. This microbanding may represent another proxy for high-resolution estimates of variance in marine palaeo-temperatures, particularly during cooler SST years.

  3. Fine-Scale Skeletal Banding Can Distinguish Symbiotic from Asymbiotic Species among Modern and Fossil Scleractinian Corals

    PubMed Central

    Frankowiak, Katarzyna; Kret, Sławomir; Mazur, Maciej; Meibom, Anders; Kitahara, Marcelo V.; Stolarski, Jarosław

    2016-01-01

    Understanding the evolution of scleractinian corals on geological timescales is key to predict how modern reef ecosystems will react to changing environmental conditions in the future. Important to such efforts has been the development of several skeleton-based criteria to distinguish between the two major ecological groups of scleractinians: zooxanthellates, which live in symbiosis with dinoflagellate algae, and azooxanthellates, which lack endosymbiotic dinoflagellates. Existing criteria are based on overall skeletal morphology and bio/geo-chemical indicators—none of them being particularly robust. Here we explore another skeletal feature, namely fine-scale growth banding, which differs between these two groups of corals. Using various ultra-structural imaging techniques (e.g., TEM, SEM, and NanoSIMS) we have characterized skeletal growth increments, composed of doublets of optically light and dark bands, in a broad selection of extant symbiotic and asymbiotic corals. Skeletons of zooxanthellate corals are characterized by regular growth banding, whereas in skeletons of azooxanthellate corals the growth banding is irregular. Importantly, the regularity of growth bands can be easily quantified with a coefficient of variation obtained by measuring bandwidths on SEM images of polished and etched skeletal surfaces of septa and/or walls. We find that this coefficient of variation (lower values indicate higher regularity) ranges from ~40 to ~90% in azooxanthellate corals and from ~5 to ~15% in symbiotic species. With more than 90% (28 out of 31) of the studied corals conforming to this microstructural criterion, it represents an easy and robust method to discriminate between zooxanthellate and azooxanthellate corals. This microstructural criterion has been applied to the exceptionally preserved skeleton of the Triassic (Norian, ca. 215 Ma) scleractinian Volzeia sp., which contains the first example of regular, fine-scale banding of thickening deposits in a fossil

  4. Fine-Scale Skeletal Banding Can Distinguish Symbiotic from Asymbiotic Species among Modern and Fossil Scleractinian Corals.

    PubMed

    Frankowiak, Katarzyna; Kret, Sławomir; Mazur, Maciej; Meibom, Anders; Kitahara, Marcelo V; Stolarski, Jarosław

    2016-01-01

    Understanding the evolution of scleractinian corals on geological timescales is key to predict how modern reef ecosystems will react to changing environmental conditions in the future. Important to such efforts has been the development of several skeleton-based criteria to distinguish between the two major ecological groups of scleractinians: zooxanthellates, which live in symbiosis with dinoflagellate algae, and azooxanthellates, which lack endosymbiotic dinoflagellates. Existing criteria are based on overall skeletal morphology and bio/geo-chemical indicators-none of them being particularly robust. Here we explore another skeletal feature, namely fine-scale growth banding, which differs between these two groups of corals. Using various ultra-structural imaging techniques (e.g., TEM, SEM, and NanoSIMS) we have characterized skeletal growth increments, composed of doublets of optically light and dark bands, in a broad selection of extant symbiotic and asymbiotic corals. Skeletons of zooxanthellate corals are characterized by regular growth banding, whereas in skeletons of azooxanthellate corals the growth banding is irregular. Importantly, the regularity of growth bands can be easily quantified with a coefficient of variation obtained by measuring bandwidths on SEM images of polished and etched skeletal surfaces of septa and/or walls. We find that this coefficient of variation (lower values indicate higher regularity) ranges from ~40 to ~90% in azooxanthellate corals and from ~5 to ~15% in symbiotic species. With more than 90% (28 out of 31) of the studied corals conforming to this microstructural criterion, it represents an easy and robust method to discriminate between zooxanthellate and azooxanthellate corals. This microstructural criterion has been applied to the exceptionally preserved skeleton of the Triassic (Norian, ca. 215 Ma) scleractinian Volzeia sp., which contains the first example of regular, fine-scale banding of thickening deposits in a fossil coral

  5. Shear bands in concentrated bacterial suspensions under oscillatory shear

    NASA Astrophysics Data System (ADS)

    Cheng, Xiang; Samanta, Devranjan; Xu, Xinliang

    2016-11-01

    Bacterial suspensions show interesting rheological behaviors such as a remarkable "superfluidic" state with vanishing viscosity. Although the bulk rheology of bacterial suspensions has been experimentally studied, shear profiles within bacterial suspensions have not been systematically explored so far. Here, by combining confocal rheometry with PIV, we investigated the flow behaviors of concentrated E. coli suspensions under planar oscillatory shear. We found that concentrated bacterial suspensions exhibit strong non-homogeneous flow profiles at low shear rates, where shear rates vanish away from the moving shear plate. We characterized the shape of the nonlinear shear profiles at different applied shear rates and bacterial concentrations and activities. The shear profiles follow a simple scaling relation with the applied shear rates and the enstrophy of suspensions, unexpected from the current hydrodynamic models of active fluids. We demonstrated that this scaling relation can be quantitatively understood by considering the power output of bacteria at different orientations with respect to shear flows. Our experiments reveal a profound influence of shear flows on the locomotion of bacteria and provide new insights into the dynamics of active fluids. The research is funded by ACS Petroleum Research Fund (54168-DNI9) and by the David & Lucile Packard Foundation. X. X. acknowledges support by the National Natural Science Foundation of China No. 11575020.

  6. Shear Banding of Soft Glassy Materials in Large Amplitude Oscillatory Shear

    NASA Astrophysics Data System (ADS)

    Radhakrishnan, Rangarajan; Fielding, Suzanne M.

    2016-10-01

    We study shear banding in soft glassy materials subject to a large amplitude oscillatory shear flow (LAOS). By numerical simulations of the widely used soft glassy rheology model, supplemented by more general physical arguments, we demonstrate strong banding over an extensive range of amplitudes and frequencies of the imposed shear rate γ ˙(t )=γ˙0cos (ω t ), even in materials that do not permit banding as their steady state response to a steadily imposed shear flow γ ˙=γ˙0=const. Highly counterintuitively, banding persists in LAOS even in the limit of zero frequency ω →0 , where one might a priori have expected a homogeneous flow response in a material that does not display banding under conditions of steadily imposed shear. We explain this finding in terms of an alternating competition within each cycle between glassy aging and flow rejuvenation. Our predictions have far-reaching implications for the flow behavior of aging yield stress fluids, suggesting a generic expectation of shear banding in flows of even arbitrarily slow time variation.

  7. Throwing out the rules: anticipatory alpha-band oscillatory attention mechanisms during task-set reconfigurations

    PubMed Central

    Foxe, John J.; Murphy, Jeremy W.; De Sanctis, Pierfilippo

    2015-01-01

    We assessed the role of alpha-band oscillatory activity during a task-switching design that required participants to switch between an auditory and a visual task, while task-relevant audio-visual inputs were simultaneously presented. Instructional cues informed participants which task to perform on a given trial and we assessed alpha-band power in the short 1.35-second period intervening between the cue and the task-imperative stimuli, on the premise that attentional biasing mechanisms would be deployed to resolve competition between the auditory and visual inputs. Prior work had shown that alpha-band activity was differentially deployed depending on the modality of the cued task. Here, we asked whether this activity would, in turn, be differentially deployed depending on whether participants had just made a switch of task, or were being asked to simply repeat the task. It is well-established that performance speed and accuracy are poorer on switch than on repeat trials. Here, however, the use of instructional cues completely mitigated these classic switch-costs. Measures of alpha-band synchronization/desynchronization showed that there was indeed greater and earlier differential deployment of alpha-band activity on switch versus repeat trials. Contrary to our hypothesis, this differential effect was entirely due to changes in the amount of desynchronization observed during switch and repeat trials of the visual task, with more desynchronization over both posterior and frontal scalp regions during switch-visual trials. These data imply that particularly vigorous, and essentially fully effective, anticipatory biasing mechanisms resolved the competition between competing auditory and visual inputs when a rapid switch of task was required. PMID:24689983

  8. Factor structure of the human gamma band oscillatory response to visual (contrast) stimulation.

    PubMed

    Carozzo, Simone; De Carli, Fabrizio; Beelke, Manolo; Saturno, Moreno; Garbarino, Sergio; Martello, Cristina; Sannita, Walter G

    2004-07-01

    Visual contrast stimulation evokes in man an oscillatory mass response at approximately 20.0-35.0 Hz, consistent with stimulus-dependent synchronous oscillations in multiunit animal recordings from visual cortex, but shorter in duration and phase-locked to stimulus. A factor analysis was applied to characterize the signal structure under stimulus conditions inducing an oscillatory response and to identify possible subcomponents in normal volunteers. Contrast stimuli were gratings with a sinusoidal luminance profile (9.0 degrees; 5.0 cycle/degree; 80% contrast; reversal 1.06 Hz). The amplitude spectrum of the signal was computed by Discrete Fourier Transform (DFT) and the oscillatory response was separated from the corresponding visually evoked potential (VEP) by DFT high-pass filter at 19.0 Hz. Nine consecutive waves were identified in all subjects (60 volunteers), with amplitudes/latencies consistent with normative studies. A factor analysis was computed 1- in the frequency domain, on the amplitude values of the signal components (2 Hz resolution), and 2- in the time domain, on the latencies/amplitudes of the averaged VEP and oscillatory responses. (1) Two non-overlapping factors accounted for the approximately 2-20.0 and approximately 20.0-40.0 Hz signal components, with separation of the approximately 20.0-35.0 Hz oscillatory response from low frequency VEPs. (2) Two factors on latencies and one factor on amplitudes (independent of each other and from those of VEPs) accounted for the average approximately 20.0-35.0 Hz oscillatory response. The factor structure further indicates an oscillatory structure and some independence from conventional VEPs of the human oscillatory response to contrast, with a separation between the oscillatory response early and late waves possibly reflecting functional differences.

  9. Colorful Structure at Fine Scales

    NASA Image and Video Library

    2017-09-07

    These are the highest-resolution color images of any part of Saturn's rings, to date, showing a portion of the inner-central part of the planet's B Ring. The view is a mosaic of two images that show a region that lies between 61,300 and 65,600 miles (98,600 and 105,500 kilometers) from Saturn's center. This image is a natural color composite, created using images taken with red, green and blue spectral filters. The pale tan color is generally not perceptible with the naked eye in telescope views, especially given that Saturn has a similar hue. The material responsible for bestowing this color on the rings -- which are mostly water ice and would otherwise appear white -- is a matter of intense debate among ring scientists that will hopefully be settled by new in-situ observations before the end of Cassini's mission. The different ringlets seen here are part of what is called the "irregular structure" of the B ring. Cassini radio occultations of the rings have shown that these features have extremely sharp boundaries on even smaller scales (radially, or along the direction outward from Saturn) than the camera can resolve here. Closer to Saturn, the irregular structures become fuzzier and more rounded, less opaque, and their color contrast diminishes. The narrow ringlets in the middle of this scene are each about 25 miles (40 kilometers) wide, and the broader bands at right are about 200 to 300 miles (300 to 500 kilometers) across. It remains unclear exactly what causes the variable brightness of these ringlets and bands -- the basic brightness of the ring particles themselves, shadowing on their surfaces, their absolute abundance, and how densely the particles are packed, may all play a role. The second image (Figure 1) is a color-enhanced version. Blue colors represent areas where the spectrum at visible wavelengths is less reddish (meaning the spectrum is flatter toward red wavelengths), while red colors represent areas that are spectrally redder (meaning the

  10. Susceptibility to distraction in autism spectrum disorder: Probing the integrity of oscillatory alpha-band suppression mechanisms

    PubMed Central

    Murphy, Jeremy W.; Foxe, John J.; Peters, Joanna B.; Molholm, Sophie

    2014-01-01

    Scientific Abstract When attention is directed to one information stream over another, the brain can be configured in advance to selectively process the relevant stream and suppress potentially distracting inputs. One key mechanism of suppression is through the deployment of anticipatory alpha-band (~10Hz) oscillatory activity, with greater alpha-band power observed in cortical regions that will ultimately process the distracting stream. Atypical attention has been implicated in autism spectrum disorder (ASD), including greater interference by distracting task-irrelevant inputs. Here we tested the integrity of these alpha-band mechanisms in ASD using an intersensory attention task. EEG was recorded while participants were cued on a trial-by-trial basis to selectively deploy attention to the visual or auditory modality in anticipation of a target within the cued modality. Whereas typically developing children showed the predicted alpha-band modulation, with increased alpha-band power over parieto-occipital scalp when attention was deployed to the auditory compared to the visual modality, this differential pattern was entirely absent at the group level in the ASD cohort. Further, only the ASD group showed impaired performance due to the presence of task-irrelevant sensory information. These data suggest that impaired modulation of alpha-band activity plays a role in increased distraction from extraneous sensory inputs in ASD. PMID:24678054

  11. Oscillatory Alpha-Band Suppression Mechanisms during the Rapid Attentional Shifts Required to Perform an Anti-Saccade Task

    PubMed Central

    Belyusar, Daniel; Snyder, Adam C.; Frey, Hans-Peter; Harwood, Mark R.; Wallman, Josh; Foxe, John J.

    2015-01-01

    Neuroimaging has demonstrated anatomical overlap between covert and overt attention systems, although behavioral and electrophysiological studies have suggested that the two systems do not rely on entirely identical circuits or mechanisms. In a parallel line of research, topographically-specific modulations of alpha-band power (~8-14Hz) have been consistently correlated with anticipatory states during tasks requiring covert attention shifts. These tasks, however, typically employ cue-target-interval paradigms where attentional processes are examined across relatively protracted periods of time and not at the rapid timescales implicated during overt attention tasks. The anti-saccade task, where one must first covertly attend for a peripheral target, before executing a rapid overt attention shift (i.e. a saccade) to the opposite side of space, is particularly well-suited for examining the rapid dynamics of overt attentional deployments. Here, we asked whether alpha-band oscillatory mechanisms would also be associated with these very rapid overt shifts, potentially representing a common neural mechanism across overt and covert attention systems. High-density electroencephalography in conjunction with infra-red eye-tracking was recorded while participants engaged in both pro- and anti- saccade task blocks. Alpha power, time-locked to saccade onset, showed three distinct phases of significantly lateralized topographic shifts, all occurring within a period of less than one second, closely reflecting the temporal dynamics of anti-saccade performance. Only two such phases were observed during the pro-saccade task. These data point to substantially more rapid temporal dynamics of alpha-band suppressive mechanisms than previously established, and implicate oscillatory alpha-band activity as a common mechanism across both overt and covert attentional deployments. PMID:23041338

  12. Fine-scale characteristics of interplanetary sector

    NASA Technical Reports Server (NTRS)

    Behannon, K. W.; Neubauer, F. M.; Barnstoff, H.

    1980-01-01

    The structure of the interplanetary sector boundaries observed by Helios 1 within sector transition regions was studied. Such regions consist of intermediate (nonspiral) average field orientations in some cases, as well as a number of large angle directional discontinuities (DD's) on the fine scale (time scales 1 hour). Such DD's are found to be more similar to tangential than rotational discontinuities, to be oriented on average more nearly perpendicular than parallel to the ecliptic plane to be accompanied usually by a large dip ( 80%) in B and, with a most probable thickness of 3 x 10 to the 4th power km, significantly thicker previously studied. It is hypothesized that the observed structures represent multiple traversals of the global heliospheric current sheet due to local fluctuations in the position of the sheet. There is evidence that such fluctuations are sometimes produced by wavelike motions or surface corrugations of scale length 0.05 - 0.1 AU superimposed on the large scale structure.

  13. Geomedia: Mapping Colorado at a fine scale

    USGS Publications Warehouse

    Orndorff, R.

    2003-01-01

    Currently, only 24 percent of Colorado's spectacular geology has been mapped at the fine scale of 1:24,000. At the same time, the state hosts many geologic hazards. Most maps of Colorado are at much broader scales, failing to show detail of basic geology crucial to safe engineering and building practices in a state that had the third-fastest-growing population during the 1990s. And the 2000 Census showed that the state, despite some economic woes, remains one of the fastest growing. Detailed geologic maps also aid the mineral industries that help fuel such growth. Since 1992, the Colorado Geological Survey (CGS) has mapped 1:24,000-scale quadrangles in high-impact areas under the STATEMAP component of the National Cooperative Geologic Mapping Program. In 2002, CGS completed its 43rd geologic quadrangle map. The long-range plan for the state is to complete 116 high-priority quadrangles in the next 15 years. The survey's approach is to select rapidly growing areas with relatively high potential for hazards and map contiguous quadrangles. In addition to mapping bedrock, CGS geologists have mapped the Quaternary deposits at the surface. Understanding these deposits is extremely important for implementing sound engineering practices because of potential for subsidence and landslides. The CGS mapping has not only yielded information about potential hazards, but also advanced scientific understanding of the state.

  14. The effects of L-theanine on alpha-band oscillatory brain activity during a visuo-spatial attention task.

    PubMed

    Gomez-Ramirez, Manuel; Kelly, Simon P; Montesi, Jennifer L; Foxe, John J

    2009-06-01

    Background/Objectives Ingestion of the non-proteinic amino acid L-theanine (gamma-glutamylethylamide) has been shown to influence oscillatory brain activity in the alpha band (8-14 Hz) in humans during resting electroencephalographic (EEG) recordings and also during cognitive task performance. We have previously shown that ingestion of a 250-mg dose of L-theanine significantly reduced tonic (background) alpha power during a demanding intersensory (auditory-visual) attentional cueing task. Further, cue-related phasic changes in alpha power, indexing the shorter-term anticipatory biasing of attention between modalities, were stronger on L-theanine compared to placebo. This form of cue-contingent phasic alpha activity is also known to index attentional biasing within visual space. Specifically, when a relevant location is pre-cued, anticipatory alpha power increases contralateral to the location to be ignored. Here we investigate whether the effects of L-theanine on tonic and phasic alpha activity, found previously during intersensory attentional deployment, occur also during a visuospatial task. Subjects/Methods 168-channel EEG data were recorded from thirteen neurologically normal individuals while engaged in a highly demanding visuo-spatial attention task. Participants underwent testing on two separate days, ingesting either a 250-mg colorless and tasteless solution of L-theanine mixed with water, or a water-based solution placebo on each day in counterbalanced order. We compared the alpha-band activity when subjects ingested L-Theanine vs. Placebo. Results We found a significant reduction in tonic alpha for the L-theanine treatment compared to placebo, which was accompanied by a shift in scalp topography, indicative of treatment-related changes in the neural generators of oscillatory alpha activity. However, L-theanine did not measurably affect cue-related anticipatory alpha effects. Conclusions This pattern of results implies that L-theanine plays a more general

  15. Temporal expectation and attention jointly modulate auditory oscillatory activity in the beta band.

    PubMed

    Todorovic, Ana; Schoffelen, Jan-Mathijs; van Ede, Freek; Maris, Eric; de Lange, Floris P

    2015-01-01

    The neural response to a stimulus is influenced by endogenous factors such as expectation and attention. Current research suggests that expectation and attention exert their effects in opposite directions, where expectation decreases neural activity in sensory areas, while attention increases it. However, expectation and attention are usually studied either in isolation or confounded with each other. A recent study suggests that expectation and attention may act jointly on sensory processing, by increasing the neural response to expected events when they are attended, but decreasing it when they are unattended. Here we test this hypothesis in an auditory temporal cueing paradigm using magnetoencephalography in humans. In our study participants attended to, or away from, tones that could arrive at expected or unexpected moments. We found a decrease in auditory beta band synchrony to expected (versus unexpected) tones if they were unattended, but no difference if they were attended. Modulations in beta power were already evident prior to the expected onset times of the tones. These findings suggest that expectation and attention jointly modulate sensory processing.

  16. Temporal Expectation and Attention Jointly Modulate Auditory Oscillatory Activity in the Beta Band

    PubMed Central

    Todorovic, Ana; Schoffelen, Jan-Mathijs; van Ede, Freek; Maris, Eric; de Lange, Floris P.

    2015-01-01

    The neural response to a stimulus is influenced by endogenous factors such as expectation and attention. Current research suggests that expectation and attention exert their effects in opposite directions, where expectation decreases neural activity in sensory areas, while attention increases it. However, expectation and attention are usually studied either in isolation or confounded with each other. A recent study suggests that expectation and attention may act jointly on sensory processing, by increasing the neural response to expected events when they are attended, but decreasing it when they are unattended. Here we test this hypothesis in an auditory temporal cueing paradigm using magnetoencephalography in humans. In our study participants attended to, or away from, tones that could arrive at expected or unexpected moments. We found a decrease in auditory beta band synchrony to expected (versus unexpected) tones if they were unattended, but no difference if they were attended. Modulations in beta power were already evident prior to the expected onset times of the tones. These findings suggest that expectation and attention jointly modulate sensory processing. PMID:25799572

  17. Impairments in Background and Event-Related Alpha-Band Oscillatory Activity in Patients with Schizophrenia

    PubMed Central

    Abeles, Ilana Y.; Gomez-Ramirez, Manuel

    2014-01-01

    Studies show that patients with schizophrenia exhibit impaired responses to sensory stimuli, especially at the early stages of neural processing. In particular, patients’ alpha-band (8–14 Hz) event-related desynchronization (ERD) and visual P1 event-related potential (ERP) component tend to be significantly reduced, with P1 ERP deficits greater for visual stimuli biased towards the magnocellular system. In healthy controls, studies show that pre-stimulus alpha (background alpha) plays a pivotal role in sensory processing and behavior, largely by shaping the neural responses to incoming stimuli. Here, we address whether patients’ ERD and P1 deficits stem from impairments in pre-stimulus alpha mechanisms. To address this question we recorded electrophysiological activity in patients with schizophrenia and healthy controls while they engaged in a visual discrimination task with low, medium, and high contrast stimuli. The results revealed a significant decrease in patients’ ERDs, which was largely driven by reductions in pre-stimulus alpha. These reductions were most prominent in right-hemispheric areas. We also observed a systematic relationship between pre-stimulus alpha and the P1 component across different contrast levels. However, this relationship was only observed in healthy controls. Taken together, these findings highlight a substantial anomaly in patients’ amplitude-based alpha background activity over visual areas. The results provide further support that pre-stimulus alpha activity plays an active role in perception by modulating the neural responses to incoming sensory inputs, a mechanism that seems to be compromised in schizophrenia. PMID:24646909

  18. Sexual recombination in Colletotrichum lindemuthianum occurs on a fine scale.

    PubMed

    Souza, E A; Camargo, O A; Pinto, J M A

    2010-09-08

    Glomerella cingulata f. sp phaseoli is the sexual phase of the fungus Colletotrichum lindemuthianum, the causal agent of common bean anthracnose. This fungus is of great concern, because it causes large economic losses in common bean crops. RAPD markers of five populations of G. cingulata f. sp phaseoli from two Brazilian states were analyzed to determine if this population possesses the sexual reproductive potential to generate the genetic variation that is observed in this phytopathogen. We identified 128 polymorphic bands, amplified by 28 random primers. The estimates of genetic similarity in this analysis ranged from 0.43 to 1.00, and the dendrogram generated from analysis of all genotypes displayed five principal groups, coinciding with the five populations. Genetic differentiation was observed between the populations (GST=0.6455); 69% of the overall observed genetic variation was between individual populations and 31% of the variance was within the sub-populations. We identified significant levels of linkage disequilibrium in all populations. However, the values of the disequilibrium ranged from low to moderate, indicating that this pathogen maintains a genetic structure consistent with sexual reproduction. The mean contribution of sexual reproduction was determined by comparison of the amplitudes of genetic similarity of isolates from sexual and asexual phases. These results support the hypothesis that recombination plays an important role in determining the amplitude of variability in this pathogen population and that this determination occurs on a fine scale.

  19. Landscape and fine scale habitat associations of the Loggerhead Shrike

    USGS Publications Warehouse

    Michaels, H.L.; Cully, J.E.

    1998-01-01

    This study was conducted to determine landscape and fine-scale vegetative variables associated with breeding Loggerhead Shrikes (Lanius ludovicianus) on Fort Riley Military Reservation, Kansas. Because Fort Riley is an Army training site, the influences of training disturbance to the vegetation, and range management practices on bird habitat patterns were also investigated. Breeding birds were surveyed in 1995 and 1996 using point counts. Survey plots were identified, a priori, at the landscape scale as either grassland, savannah, or woodland edge according to cover by woody vegetation. In 1996, fine-scale habitat at survey points and at bird use sites was measured and a principal components analysis used to characterize the fine-scale herbaceous vegetation structure. A military disturbance index was developed to quantify the severity of vehicle disturbance to the vegetation at survey and bird use sites. Shrikes were associated with savannah habitat at the landscape scale. Sites used by Loggerhead Shrikes were characterized at the fine-scale by tall, sparse, structurally heterogeneous herbaceous vegetation with high standing dead plant cover and low litter cover. At the fine-scale, tree and shrub density did not differ between sites used and not used by shrikes. Used sites did not differ from survey sites with respect to military training disturbance, hay harvest, or the number of years since a site was last burned. Our results in this study suggest that the shifting mosaic of vegetation on Fort Riley resulting from training and range management practices maintains adequate habitat for breeding shrikes.

  20. On the Lundgren-Townsend model of turbulent fine scales

    NASA Astrophysics Data System (ADS)

    Pullin, D. I.; Saffman, P. G.

    1993-01-01

    Vorticity and velocity-derivative moments for homogeneous isotropic turbulence are calculated using the strained-spiral vortex model of turbulent fine scales given by Lundgren (1982). A specific form of the relaxing spiral vortex is proposed, modeled by a rolling-up vortex layer embedded in a background containing opposite signed vorticity and with zero total circulation at infinity.

  1. Anticipatory attentional suppression of visual features indexed by oscillatory alpha-band power increases: a high-density electrical mapping study.

    PubMed

    Snyder, Adam C; Foxe, John J

    2010-03-17

    Retinotopically specific increases in alpha-band ( approximately 10 Hz) oscillatory power have been strongly implicated in the suppression of processing for irrelevant parts of the visual field during the deployment of visuospatial attention. Here, we asked whether this alpha suppression mechanism also plays a role in the nonspatial anticipatory biasing of feature-based attention. Visual word cues informed subjects what the task-relevant feature of an upcoming visual stimulus (S2) was, while high-density electroencephalographic recordings were acquired. We examined anticipatory oscillatory activity in the Cue-to-S2 interval ( approximately 2 s). Subjects were cued on a trial-by-trial basis to attend to either the color or direction of motion of an upcoming dot field array, and to respond when they detected that a subset of the dots differed from the majority along the target feature dimension. We used the features of color and motion, expressly because they have well known, spatially separated cortical processing areas, to distinguish shifts in alpha power over areas processing each feature. Alpha power from dorsal regions increased when motion was the irrelevant feature (i.e., color was cued), and alpha power from ventral regions increased when color was irrelevant. Thus, alpha-suppression mechanisms appear to operate during feature-based selection in much the same manner as has been shown for space-based attention.

  2. Oscillatory alpha-band mechanisms and the deployment of spatial attention to anticipated auditory and visual target locations: Supramodal or sensory-specific control mechanisms?

    PubMed Central

    Banerjee, Snigdha; Snyder, Adam C.; Molholm, Sophie; Foxe, John J.

    2011-01-01

    Oscillatory alpha-band activity (8–15 Hz) over parieto-occipital cortex in humans plays an important role in suppression of processing for inputs at to-be-ignored regions of space, with increased alpha-band power observed over cortex contralateral to locations expected to contain distractors. It is unclear if similar processes operate during deployment of spatial attention in other sensory modalities. Evidence from lesion patients suggests that parietal regions house supramodal representations of space. The parietal lobes are prominent generators of alpha-oscillations; raising the possibility that alpha is a neural signature of supramodal spatial attention. Further, when spatial attention is deployed within vision, processing of task-irrelevant auditory inputs at attended locations is also enhanced, pointing to automatic links between spatial deployments across senses. Here, we asked whether lateralized alpha-band activity is also evident in a purely auditory spatial-cueing task, and whether it had the same underlying generator configuration as in a purely visuo-spatial task. If common to both sensory-systems, this would provide strong support for “supramodal” attention theory. Alternately, alpha-band differences between auditory and visual tasks would support a sensory-specific account. Lateralized shifts in alpha-band activity were indeed observed during a purely auditory-spatial task. Crucially, there were clear differences in scalp topographies of this alpha-activity depending on the sensory system within which spatial attention was deployed. Findings suggest that parietally-generated alpha-band mechanisms are central to attentional deployments across modalities but that they are invoked in a sensory-specific manner. The data support an interactivity account, whereby a supramodal system interacts with sensory-specific control systems during deployment of spatial attention. PMID:21734284

  3. A fine-scale chimpanzee genetic map from population sequencing.

    PubMed

    Auton, Adam; Fledel-Alon, Adi; Pfeifer, Susanne; Venn, Oliver; Ségurel, Laure; Street, Teresa; Leffler, Ellen M; Bowden, Rory; Aneas, Ivy; Broxholme, John; Humburg, Peter; Iqbal, Zamin; Lunter, Gerton; Maller, Julian; Hernandez, Ryan D; Melton, Cord; Venkat, Aarti; Nobrega, Marcelo A; Bontrop, Ronald; Myers, Simon; Donnelly, Peter; Przeworski, Molly; McVean, Gil

    2012-04-13

    To study the evolution of recombination rates in apes, we developed methodology to construct a fine-scale genetic map from high-throughput sequence data from 10 Western chimpanzees, Pan troglodytes verus. Compared to the human genetic map, broad-scale recombination rates tend to be conserved, but with exceptions, particularly in regions of chromosomal rearrangements and around the site of ancestral fusion in human chromosome 2. At fine scales, chimpanzee recombination is dominated by hotspots, which show no overlap with those of humans even though rates are similarly elevated around CpG islands and decreased within genes. The hotspot-specifying protein PRDM9 shows extensive variation among Western chimpanzees, and there is little evidence that any sequence motifs are enriched in hotspots. The contrasting locations of hotspots provide a natural experiment, which demonstrates the impact of recombination on base composition.

  4. Fine-scale human genetic structure in Western France.

    PubMed

    Karakachoff, Matilde; Duforet-Frebourg, Nicolas; Simonet, Floriane; Le Scouarnec, Solena; Pellen, Nadine; Lecointe, Simon; Charpentier, Eric; Gros, Françoise; Cauchi, Stéphane; Froguel, Philippe; Copin, Nane; Le Tourneau, Thierry; Probst, Vincent; Le Marec, Hervé; Molinaro, Sabrina; Balkau, Beverley; Redon, Richard; Schott, Jean-Jacques; Blum, Michael Gb; Dina, Christian

    2015-06-01

    The difficulties arising from association analysis with rare variants underline the importance of suitable reference population cohorts, which integrate detailed spatial information. We analyzed a sample of 1684 individuals from Western France, who were genotyped at genome-wide level, from two cohorts D.E.S.I.R and CavsGen. We found that fine-scale population structure occurs at the scale of Western France, with distinct admixture proportions for individuals originating from the Brittany Region and the Vendée Department. Genetic differentiation increases with distance at a high rate in these two parts of Northwestern France and linkage disequilibrium is higher in Brittany suggesting a lower effective population size. When looking for genomic regions informative about Breton origin, we found two prominent associated regions that include the lactase region and the HLA complex. For both the lactase and the HLA regions, there is a low differentiation between Bretons and Irish, and this is also found at the genome-wide level. At a more refined scale, and within the Pays de la Loire Region, we also found evidence of fine-scale population structure, although principal component analysis showed that individuals from different departments cannot be confidently discriminated. Because of the evidence for fine-scale genetic structure in Western France, we anticipate that rare and geographically localized variants will be identified in future full-sequence analyses.

  5. Fine-scale human genetic structure in Western France

    PubMed Central

    Karakachoff, Matilde; Duforet-Frebourg, Nicolas; Simonet, Floriane; Le Scouarnec, Solena; Pellen, Nadine; Lecointe, Simon; Charpentier, Eric; Gros, Françoise; Cauchi, Stéphane; Froguel, Philippe; Copin, Nane; Balkau, B; Ducimetière, P; Eschwège;, E; Alhenc-Gelas, F; Girault, A; Fumeron, F; Marre, M; Roussel, R; Bonnet, F; Cauchi, S; Froguel, P; Cogneau, J; Born, C; Caces, E; Cailleau, M; Lantieri, O; Moreau, J G; Rakotozafy, F; Tichet, J; Le Tourneau, Thierry; Probst, Vincent; Le Marec, Hervé; Molinaro, Sabrina; Balkau, Beverley; Redon, Richard; Schott, Jean-Jacques; Blum, Michael GB; Dina, Christian

    2015-01-01

    The difficulties arising from association analysis with rare variants underline the importance of suitable reference population cohorts, which integrate detailed spatial information. We analyzed a sample of 1684 individuals from Western France, who were genotyped at genome-wide level, from two cohorts D.E.S.I.R and CavsGen. We found that fine-scale population structure occurs at the scale of Western France, with distinct admixture proportions for individuals originating from the Brittany Region and the Vendée Department. Genetic differentiation increases with distance at a high rate in these two parts of Northwestern France and linkage disequilibrium is higher in Brittany suggesting a lower effective population size. When looking for genomic regions informative about Breton origin, we found two prominent associated regions that include the lactase region and the HLA complex. For both the lactase and the HLA regions, there is a low differentiation between Bretons and Irish, and this is also found at the genome-wide level. At a more refined scale, and within the Pays de la Loire Region, we also found evidence of fine-scale population structure, although principal component analysis showed that individuals from different departments cannot be confidently discriminated. Because of the evidence for fine-scale genetic structure in Western France, we anticipate that rare and geographically localized variants will be identified in future full-sequence analyses. PMID:25182131

  6. Oscillatory bands, neuronal synchrony and hippocampal function: implications of the effects of prenatal choline supplementation for sleep-dependent memory consolidation.

    PubMed

    Cheng, Ruey-Kuang; Williams, Christina L; Meck, Warren H

    2008-10-27

    Choline supplementation of the maternal diet has long-term facilitative effects on spatial and temporal memory processes in the offspring. To further delineate the impact of early nutritional status on brain and behavior, we examined effects of prenatal-choline availability on hippocampal oscillatory frequency bands in 12 month-old male and female rats. Adult offspring of time-pregnant dams that were given a deficient level of choline (DEF=0.0 g/kg), sufficient choline (CON=1.1 g/kg) or supplemental choline (SUP=3.5 g/kg) in their chow during embryonic days (ED) 12-17 were implanted with an electroencephalograph (EEG) electrode in the hippocampal dentate gyrus in combination with an electromyograph (EMG) electrode patch implanted in the nuchal muscle. Five consecutive 8-h recording sessions revealed differential patterns of EEG activity as a function of awake, slow-wave sleep (SWS) and rapid-eye movement (REM) sleep states and prenatal choline status. The main finding was that SUP rats displayed increased power levels of gamma (30-100 Hz) band oscillations during all phases of the sleep/wake cycle. These findings are discussed within the context of a general review of neuronal oscillations (e.g., delta, theta, and gamma bands) and synchronization across multiple brain regions in relation to sleep-dependent memory consolidation in the hippocampus.

  7. Fine-Scale Movements of the Broadnose Sevengill Shark and Its Main Prey, the Gummy Shark

    PubMed Central

    Barnett, Adam; Abrantes, Kátya G.; Stevens, John D.; Bruce, Barry D.; Semmens, Jayson M.

    2010-01-01

    Information on the fine-scale movement of predators and their prey is important to interpret foraging behaviours and activity patterns. An understanding of these behaviours will help determine predator-prey relationships and their effects on community dynamics. For instance understanding a predator's movement behaviour may alter pre determined expectations of prey behaviour, as almost any aspect of the prey's decisions from foraging to mating can be influenced by the risk of predation. Acoustic telemetry was used to study the fine-scale movement patterns of the Broadnose Sevengill shark Notorynchus cepedianus and its main prey, the Gummy shark Mustelus antarcticus, in a coastal bay of southeast Tasmania. Notorynchus cepedianus displayed distinct diel differences in activity patterns. During the day they stayed close to the substrate (sea floor) and were frequently inactive. At night, however, their swimming behaviour continually oscillated through the water column from the substrate to near surface. In contrast, M. antarcticus remained close to the substrate for the entire diel cycle, and showed similar movement patterns for day and night. For both species, the possibility that movement is related to foraging behaviour is discussed. For M. antarcticus, movement may possibly be linked to a diet of predominantly slow benthic prey. On several occasions, N. cepedianus carried out a sequence of burst speed events (increased rates of movement) that could be related to chasing prey. All burst speed events during the day were across the substrate, while at night these occurred in the water column. Overall, diel differences in water column use, along with the presence of oscillatory behaviour and burst speed events suggest that N. cepedianus are nocturnal foragers, but may opportunistically attack prey they happen to encounter during the day. PMID:21151925

  8. A FRAMEWORK FOR FINE-SCALE COMPUTATIONAL FLUID DYNAMICS AIR QUALITY MODELING AND ANALYSIS

    EPA Science Inventory

    Fine-scale Computational Fluid Dynamics (CFD) simulation of pollutant concentrations within roadway and building microenvironments is feasible using high performance computing. Unlike currently used regulatory air quality models, fine-scale CFD simulations are able to account rig...

  9. A FRAMEWORK FOR FINE-SCALE COMPUTATIONAL FLUID DYNAMICS AIR QUALITY MODELING AND ANALYSIS

    EPA Science Inventory

    Fine-scale Computational Fluid Dynamics (CFD) simulation of pollutant concentrations within roadway and building microenvironments is feasible using high performance computing. Unlike currently used regulatory air quality models, fine-scale CFD simulations are able to account rig...

  10. Lithospheric discontinuities beneath Australia: interaction of large-scale and fine scale structure

    NASA Astrophysics Data System (ADS)

    Kennett, Brian L. N.; Yoshizawa, Kazunori

    2016-04-01

    Understanding the complex heterogeneity of the continental lithosphere involves a wide variety of spatial scales and the synthesis of multiple classes of information. Seismic surface waves and multiply reflected body waves provide the main information on broad-scale structure, and bounds on the extent of the lithosphere-asthenosphere transition (LAT) can be found from the vertical gradients of S wavespeed. Information on finer scale structures comes though body wave studies, including detailed seismic tomography and P wave reflectivity extracted from stacked autocorrelograms of continuous component records. With the inclusion of deterministic large-scale structure and realistic medium-scale stochastic features there is not a need for strong fine-scale variations. The resulting multi-scale heterogeneity model for the Australian region gives a good representation of the character of observed seismograms and their geographic variations and matches the observations of P wave reflectivity. The presence of reflections in the 0.5-3.0 Hz band in the uppermost mantle suggests variations on vertical scales of a few hundred metres with amplitudes of the order of 1%. There are some indications of a change of reflection character in the lower part of the lithosphere in the transition to the asthenosphere. In some parts of central Australia there is a reasonable tie between a change in reflectivity and other information on mid-lithospheric discontinuities. Individual seismic probes illuminate different aspects of the heterogeneity, but the full spectrum has to be taken into account to understand the properties of apparent discontinuities and their geodynamic implications. Once fine-scale structure is taken into consideration it becomes apparent that wave interference plays a very important role in determining the nature of apparent discontinuities seen with lower frequency probes such as S wave receiver functions. Changes in the character of fine-scale heterogeneity can

  11. Solar chromospheric fine scale structures: dynamics and energetics

    NASA Astrophysics Data System (ADS)

    Tziotziou, K.

    2012-01-01

    The solar chromosphere is a very inhomogeneous and dynamic layer of the solar atmosphere that exhibits several phenomena on a wide range of spatial and temporal scales. High-resolution and long-duration observations, employing mostly lines, such as Halpha, the Ca II infrared lines and the Ca II H and K lines, obtained both from ground-based telescope facilities (e.g. DST, VTT, THEMIS, SST, DOT), as well as state-of-the-art satellites (e.g. SOHO, TRACE, HINODE) reveal an incredibly rich, dynamic and highly structured chromospheric environment. What is known in literature as the chromospheric fine-scale structure mainly consists of small fibrilar-like features that connect various parts of quiet/active regions or span across the chromospheric network cell interiors, showing a large diversity of both physical and dynamic characteristics. The highly dynamic, fine-scale chromospheric structures are mostly governed by flows which reflect the complex geometry and dynamics of the local magnetic field and play an important role in the propagation and dissipation of waves. A comprehensive study of these structures requires deep understanding of the physical processes involved and investigation of their intricate link with structures/processes at lower photospheric levels. Furthermore, due to their large number present on the solar surface, it is essential to investigate their impact on the mass and energy transport to higher atmospheric layers through processes such as magnetic reconnection and propagation of waves. The in-depth study of all aforementioned characteristics and processes, with the further addition of non-LTE physics, as well as the use of three-dimensional numerical simulations poses a fascinating challenge for both theory and numerical modeling of chromospheric fine-scale structures.

  12. Fine-Scale Mechanical Properties of Sliding Solids.

    DTIC Science & Technology

    1987-02-28

    UNCLASSIFIED DRJ45-4-C-0006 F/0 26/11 ML E~Em***smRn loI 1.05 w4 AV. -w q ! WvI% %111.2nE~% 03TI ElLE CP - 1NE-CALE MECHANICAL PROPERTIES OF - 0 SLIDING...LAI 4Th Approved for Public Release; distribution unlimited f 4,rm 6mw "%U FINE-SCALE MECHANICAL PROPERTIES OF SLIDING SOLIDS Final Technical Report by...experiments specifically designed to -investigate the mechanical properties of materials at the submicroscopic level. The first part deals with

  13. Fine-scale adaptation in a clonal sea anemone.

    PubMed

    Sherman, Craig D H; Ayre, David J

    2008-06-01

    Local adaptation in response to fine-scale spatial heterogeneity is well documented in terrestrial ecosystems. In contrast, in marine environments local adaptation has rarely been documented or rigorously explored. This may reflect real or anticipated effects of genetic homogenization, resulting from widespread dispersal in the sea. However, evolutionary theory predicts that for the many benthic species with complex life histories that include both sexual and asexual phases, each parental habitat patch should become dominated by the fittest and most competitive clones. In this study we used genotypic mapping to show that within headlands, clones of the sea anemone Actinia tenebrosa show restricted distributions to specific habitats despite the potential for more widespread dispersal. On these same shores we used reciprocal transplant experiments that revealed strikingly better performance of clones within their natal rather than foreign habitats as judged by survivorship, asexual fecundity, and growth. These findings highlight the importance of selection for fine-scale environmental adaptation in marine taxa and imply that the genotypic structure of populations reflects extensive periods of interclonal competition and site-specific selection.

  14. Fine-scale transient arcs seen in a shock aurora

    NASA Astrophysics Data System (ADS)

    Motoba, T.; Ebihara, Y.; Kadokura, A.; Weatherwax, A. T.

    2014-08-01

    We report, for the first time, fine-scale transient arcs that emerged successively within the initial 1-2 min evolutionary interval of a postnoon shock aurora on 14 July 2012. Data were acquired from ~2 Hz temporal resolution imaging of dayside aurora with a white light all-sky camera (ASC) at South Pole Station (magnetic latitude = -74.3°, magnetic local time = UT -3.5 h). Just after 1809:50 UT at which the initial response to an interplanetary (IP) shock was detected in the postnoon geosynchronous magnetic field, the ASC observed three successive transient arcs of which the locations shifted equatorward with an abrupt jump by ~0.2° in latitude. All of the transient arcs occurred in a closed field line region, ~1.0°-1.5° equatorward of the polar cap or open/closed field line boundary inferred from the intensity ratio of I630.0/I557.7 but just poleward of the shock-induced proton and diffuse-type electron aurorae. Each of the transient arcs had a latitudinal width of ~0.1° and a short lifetime of ~20-30 s. Although the obvious mechanism has still remained unclear, possible interpretations of the fine-scale transient arc features are discussed in terms of a local process of each of the magnetospheric origin (mode conversion) and ionospheric origin (feedback interaction) that may be induced by IP shock.

  15. Elk winter foraging at fine scale in Yellowstone National Park.

    PubMed

    Fortin, Daniel; Morales, Juan M; Boyce, Mark S

    2005-09-01

    The link between landscape properties and foraging decisions by herbivores remains unclear, but such knowledge is central to the understanding of plant-herbivore dynamics. Our goal was to determine whether fine-scale foraging paths of free-ranging elk (Cervus canadensis) respond to spatial structure of habitats in Yellowstone National Park. During winter 2002 we gathered elk-foraging information by following snow tracks in open habitats located on hillsides and flat terrain. The 21 snow paths surveyed were comprised on average of 15 discrete snow craters connected to each other by relatively straight-line movements. Our analyses revealed two levels of selection: elk chose where to dig, and how much search effort to allocate at digging sites based on habitat characteristics. On hillsides, elk preferentially dug in areas of greater biomass of grasses and forbs, and simply walked through poorer sites without digging. Individuals also searched more intensively, creating larger craters, where food biomass was higher. On flat terrain, crater size decreased with snow depth and increased with snow density. Correlated random walk models usually were adequate to characterize elk movement on flat terrain, but not on hillsides. First, as the number of movements between local foraging areas increased, elk displacements on hillsides became shorter than expected from random patterns. This trend on hillsides was strongly influenced by interindividual variation in movement behavior. Second, elk tended to forage perpendicularly to aspect, resulting in horizontal displacements. Our study demonstrates that free-ranging elk adjust their foraging to fine-scale habitat structure.

  16. Fine-Scale Filamentary Structure in Coronal Streamers

    NASA Technical Reports Server (NTRS)

    Woo, Richard; Armstrong, John W.; Bird, Michael K.; Paetzold, Martin

    1995-01-01

    Doppler scintillation measurements of a coronal streamer lasting several solar rotations have been conducted by Ulysses in 1991 over a heliocentric distance range of 14-77 R(sub 0). By showing that the solar corona is filamentary, and that Doppler frequency is the radio counterpart of white-light eclipse pictures processed to enhance spatial gradients, it is demonstrated that Doppler scintillation measurements provide the high spatial resolution that has long eluded white-light coronagraph measurements. The region of enhanced scintillation, spanning an angular extent of 1.8 deg in heliographic longitude, coincides with the radially expanding streamer stalk and represents filamentary structure with scale sizes at least as small as 340 km (0.5 sec) when extrapolated to the Sun. Within the stalk of the streamer, the fine-scale structure corresponding to scale sizes in the range of 20-340 km at the Sun and associated with closed magnetic fields amounts to a few percent of the mean density, while outside the stalk, the fine-scale structure associated with open fields is an order of magnitude lower. Clustering of filamentary structure that takes place within the stalk of the streamer is suggestive of multiple current sheets. Comparison with ISEE 3 in situ plasma measurements shows that significant evolution resulting from dynamic interaction with increasing heliocentric distance takes place by the time streamers reach Earth orbit.

  17. The TRMM Multi-satellite Precipitation Analysis (TMPA): Quasi-Global Precipitation Estimates at Fine Scales

    NASA Technical Reports Server (NTRS)

    Huffman, George J.; Adler, Robert F.; Bolvin, David T.; Gu, Guojun; Nelkin, Eric J.; Bowman, Kenneth P.; Stocker, Erich; Wolff, David B.

    2006-01-01

    The TRMM Multi-satellite Precipitation Analysis (TMPA) provides a calibration-based sequential scheme for combining multiple precipitation estimates from satellites, as well as gauge analyses where feasible, at fine scales (0.25 degrees x 0.25 degrees and 3-hourly). It is available both after and in real time, based on calibration by the TRMM Combined Instrument and TRMM Microwave Imager precipitation products, respectively. Only the after-real-time product incorporates gauge data at the present. The data set covers the latitude band 50 degrees N-S for the period 1998 to the delayed present. Early validation results are as follows: The TMPA provides reasonable performance at monthly scales, although it is shown to have precipitation rate dependent low bias due to lack of sensitivity to low precipitation rates in one of the input products (based on AMSU-B). At finer scales the TMPA is successful at approximately reproducing the surface-observation-based histogram of precipitation, as well as reasonably detecting large daily events. The TMPA, however, has lower skill in correctly specifying moderate and light event amounts on short time intervals, in common with other fine-scale estimators. Examples are provided of a flood event and diurnal cycle determination.

  18. Object segmentation and reconstruction via an oscillatory neural network: interaction among learning, memory, topological organization and gamma-band synchronization.

    PubMed

    Magosso, E; Cuppini, C; Ursino, M

    2006-01-01

    Synchronization of neuronal activity in the gamma-band has been shown to play an important role in higher cognitive functions, by grouping together the necessary information in different cortical areas to achieve a coherent perception. In the present work, we used a neural network of Wilson-Cowan oscillators to analyze the problem of binding and segmentation of high-level objects. Binding is achieved by implementing in the network the similarity and prior knowledge Gestalt rules. Similarity law is realized via topological maps within the network. Prior knowledge originates by means of a Hebbian rule of synaptic change; objects are memorized in the network with different strengths. Segmentation is realized via a global inhibitor which allows desynchronisation among multiple objects avoiding interference. Simulation results performed with a 40x40 neural grid, using three simultaneous input objects, show that the network is able to recognize and segment objects in several different conditions (different degrees of incompleteness or distortion of input patterns), exhibiting the higher reconstruction performances the higher the strength of object memory. The presented model represents an integrated approach for investigating the relationships among learning, memory, topological organization and gamma-band synchronization.

  19. Fine scale association mapping of disease loci using simplex families.

    PubMed

    Morris, A P; Whittaker, J C

    2000-05-01

    We present a new method for the fine scale mapping of disease loci based on samples of simplex families, each containing an affected child. The method is based on a generalisation of a single locus allele transmission model to multiple marker loci. The model is developed under the assumption of a single ancestral mutation and allows for the calculation of posterior probabilities that each allele at a particular marker was present on the founder chromosome. We illustrate the method using simulated family data for cystic fibrosis and Huntingtons disease, for which the locations of mutations in the disease genes are now known. For both diseases, our new method provides good estimates of the location of the mutations.

  20. The fine scale structures of airflow over Bergen

    NASA Astrophysics Data System (ADS)

    Ólafsson, Haraldur; Rugaard Furevik, Birgitte; Asle Olseth, Jan; Edvard Grov, Ole

    2015-04-01

    A large network of automatic weather stations is operated in the the complex terrain of Bergen City and its surroundings. This so-called Bergen School of Meteorology network is used to explore the fine scale structures of the atmosphere in a föhn case and evaluate how numerical simulations perform in reproducing the details of the flow. In general, the vertical profile is well reproduced, as well as many details in the wind field, as long as the resolution permits adequate representation of the topography. The intermittent nature of the flow remains however a problem. A step towards better local forecasts may lie in predicting not only the fundamental parameters such as wind and temperature, but their local temporal variability as well.

  1. Fine-Scale Radio Studies of the Sun.

    DTIC Science & Technology

    1980-07-01

    7𔄁AD-A090 021 TUFTS UNIV MEDFORD .ASS MEPT O1F PHYSICS F/G 3/2 FINESCALE RADIO STUDIES OF THE SUN . (U) JUL 80 K R LANG, R F WILLSON FIg928-79-C-0010...UNCLASSIFIED AFGL-TR-80-O 190 NL ’!J!IEILEEIIE| llllllEEEEEnlnE ElllllllEEllEE AFGL-TR-80-0190 FINE-SCALE RADIO STUDIES OF THE SUN Kenneth R. Lang... the Sun # KY 15 Dec. 1978 - 15 June 1980. 6 PERFORMING O"G. RaPOIT %UMSE’R 7 AUTHOR~s) S. CONTRACT OR GRANT NUMIBER .i Kenneth R. Lang kRobert F

  2. Parallel integer sorting with medium and fine-scale parallelism

    NASA Technical Reports Server (NTRS)

    Dagum, Leonardo

    1993-01-01

    Two new parallel integer sorting algorithms, queue-sort and barrel-sort, are presented and analyzed in detail. These algorithms do not have optimal parallel complexity, yet they show very good performance in practice. Queue-sort designed for fine-scale parallel architectures which allow the queueing of multiple messages to the same destination. Barrel-sort is designed for medium-scale parallel architectures with a high message passing overhead. The performance results from the implementation of queue-sort on a Connection Machine CM-2 and barrel-sort on a 128 processor iPSC/860 are given. The two implementations are found to be comparable in performance but not as good as a fully vectorized bucket sort on the Cray YMP.

  3. Fine-scale mapping of meiotic recombination in Asians.

    PubMed

    Bleazard, Thomas; Ju, Young Seok; Sung, Joohon; Seo, Jeong-Sun

    2013-03-08

    Meiotic recombination causes a shuffling of homologous chromosomes as they are passed from parents to children. Finding the genomic locations where these crossovers occur is important for genetic association studies, understanding population genetic variation, and predicting disease-causing structural rearrangements. There have been several reports that recombination hotspot usage differs between human populations. But while fine-scale genetic maps exist for European and African populations, none have been constructed for Asians. Here we present the first Asian genetic map with resolution high enough to reveal hotspot usage. We constructed this map by applying a hidden Markov model to genotype data for over 500,000 single nucleotide polymorphism markers from Korean and Mongolian pedigrees which include 980 meioses. We identified 32,922 crossovers with a precision rate of 99%, 97% sensitivity, and a median resolution of 105,949 bp. For direct comparison of genetic maps between ethnic groups, we also constructed a map for CEPH families using identical methods. We found high levels of concordance with known hotspots, with approximately 72% of recombination occurring in these regions. We investigated the hypothesized contribution of recombination problems to age-related aneuploidy. Our large sample size allowed us to detect a weak but significant negative effect of maternal age on recombination rate. We have constructed the first fine-scale Asian genetic map. This fills an important gap in the understanding of recombination pattern variation and will be a valuable resource for future research in population genetics. Our map will improve the accuracy of linkage studies and inform the design of genome-wide association studies in the Asian population.

  4. A heterogeneity test for fine-scale genetic structure.

    PubMed

    Smouse, Peter E; Peakall, Rod; Gonzales, Eva

    2008-07-01

    For organisms with limited vagility and/or occupying patchy habitats, we often encounter nonrandom patterns of genetic affinity over relatively small spatial scales, labelled fine-scale genetic structure. Both the extent and decay rate of that pattern can be expected to depend on numerous interesting demographic, ecological, historical, and mating system factors, and it would be useful to be able to compare different situations. There is, however, no heterogeneity test currently available for fine-scale genetic structure that would provide us with any guidance on whether the differences we encounter are statistically credible. Here, we develop a general nonparametric heterogeneity test, elaborating on standard autocorrelation methods for pairs of individuals. We first develop a 'pooled within-population' correlogram, where the distance classes (lags) can be defined as functions of distance. Using that pooled correlogram as our null-hypothesis reference frame, we then develop a heterogeneity test of the autocorrelations among different populations, lag-by-lag. From these single-lag tests, we construct an analogous test of heterogeneity for multilag correlograms. We illustrate with a pair of biological examples, one involving the Australian bush rat, the other involving toadshade trillium. The Australian bush rat has limited vagility, and sometimes occupies patchy habitat. We show that the autocorrelation pattern diverges somewhat between continuous and patchy habitat types. For toadshade trillium, clonal replication in Piedmont populations substantially increases autocorrelation for short lags, but clonal replication is less pronounced in mountain populations. Removal of clonal replicates reduces the autocorrelation for short lags and reverses the sign of the difference between mountain and Piedmont correlograms.

  5. The fine scale genetic structure of the British population

    PubMed Central

    Davison, Dan; Boumertit, Abdelhamid; Day, Tammy; Hutnik, Katarzyna; Royrvik, Ellen C; Cunliffe, Barry; Lawson, Daniel J; Falush, Daniel; Freeman, Colin; Pirinen, Matti; Myers, Simon; Robinson, Mark; Donnelly, Peter; Bodmer, Walter

    2015-01-01

    Summary Fine-scale genetic variation between human populations is interesting as a signature of historical demographic events and because of its potential for confounding disease studies. We use haplotype-based statistical methods to analyse genome-wide SNP data from a carefully chosen geographically diverse sample of 2,039 individuals from the United Kingdom (UK). This reveals a rich and detailed pattern of genetic differentiation with remarkable concordance between genetic clusters and geography. The regional genetic differentiation and differing patterns of shared ancestry with 6,209 individuals from across Europe carry clear signals of historical demographic events. We estimate the genetic contribution to SE England from Anglo-Saxon migrations to be under half, identify the regions not carrying genetic material from these migrations, suggest significant pre-Roman but post-Mesolithic movement into SE England from the Continent, and show that in non-Saxon parts of the UK there exist genetically differentiated subgroups rather than a general “Celtic” population. PMID:25788095

  6. A Parametric Study of Fine-scale Turbulence Mixing Noise

    NASA Technical Reports Server (NTRS)

    Khavaran, Abbas; Bridges, James; Freund, Jonathan B.

    2002-01-01

    The present paper is a study of aerodynamic noise spectra from model functions that describe the source. The study is motivated by the need to improve the spectral shape of the MGBK jet noise prediction methodology at high frequency. The predicted spectral shape usually appears less broadband than measurements and faster decaying at high frequency. Theoretical representation of the source is based on Lilley's equation. Numerical simulations of high-speed subsonic jets as well as some recent turbulence measurements reveal a number of interesting statistical properties of turbulence correlation functions that may have a bearing on radiated noise. These studies indicate that an exponential spatial function may be a more appropriate representation of a two-point correlation compared to its Gaussian counterpart. The effect of source non-compactness on spectral shape is discussed. It is shown that source non-compactness could well be the differentiating factor between the Gaussian and exponential model functions. In particular, the fall-off of the noise spectra at high frequency is studied and it is shown that a non-compact source with an exponential model function results in a broader spectrum and better agreement with data. An alternate source model that represents the source as a covariance of the convective derivative of fine-scale turbulence kinetic energy is also examined.

  7. Effects of fine-scale orography on infrasound propagation

    NASA Astrophysics Data System (ADS)

    Pilger, C.; Streicher, F.; Wüst, S.; Bittner, M.

    2012-04-01

    The sensitivity of infrasound propagation to reflections by a non-flat surface is investigated within this study. Infrasound propagation modelling is performed at the German Remote Sensing Data Center of the German Aerospace Center (DLR-DFD) using improved 3d ray-tracing methods (HARPA/DLR). Terrain information is newly included in the modelling using a high-resolution digital surface model. The SRTM30-PLUS digital surface model incorporates the DLR "Shuttle Radar Topography Mission" and complementary surface information to generate a global, equidistant and complete data set for surface orography. The maximum horizontal resolution is 30 arc seconds (about 1km), the maximum vertical resolution is 1m. The resolution of the model can be adapted to the wavelength of the considered infrasound signal. The orography is implemented as background data using bicubic spline interpolation and thus provides smooth surface layer information for infrasound propagation modelling. First modelling cases containing the European Alps region show that orography has a significant influence on infrasound propagation. Ducts and propagation patterns can be veritably changed according to reflection by non-flat fine-scale orography. First results on the sensitivity of infrasound propagation to surface orography will be presented.

  8. Fine-scale genetic structuring on Manacus manacus leks.

    PubMed

    Shorey, L; Piertney, S; Stone, J; Höglund, J

    2000-11-16

    Leks have traditionally been considered as arenas where males compete to attract females and secure matings. Thus, direct fitness benefits mediated through competition between males to fertilize females have been considered to be the primary force driving the evolution of lekking behaviour. Inclusive fitness benefits mediated through kin selection may also be involved in lek formation and evolution, but to date this theory has been largely ignored. According to kin-selection theory, both reproducing and non-reproducing males may gain indirect inclusive fitness benefits. If females are attracted to larger leks, non-reproducing males add attractiveness to a lek, and therefore, in a genetically structured population, boost the reproductive success of kin. Theory predicts that the attractiveness of leks is plastic, and that males establish themselves on a lek in which the top male, in terms of reproductive success, is a close relative. Here we show that in white-bearded manakins (Manacus manacus), for which larger leks are more attractive to females and so secure the maximum number of matings, there is extraordinary fine-scale genetic structure, with leks being composed of clusters of related kin. We propose that males establish themselves where they find relatives to such an extent that they form groups within leks, and that such behaviour is consistent with kin-selection theory to maximize reproductive success of the group.

  9. Search for fine scale structures in high latitude solar wind

    NASA Astrophysics Data System (ADS)

    Livi, S.; Parenti, S.; Poletto, G.

    1995-06-01

    About 25 years ago, E. Parker suggested that, as a consequence of the inhomogeneous structure of the corona, the solar wind might consist of adjacent structures with different physical conditions. Since that suggestion was made, the solar wind plasma characteristics have been measured in situ through many experiments, but little has been done to check whether the solar wind shows any evidence for fine scale structures, and, in the affirmative, how far from the Sun these structures persist. A previous work on this subject, by Thieme, Marsch and Schwenn (1990), based on Helios data, lead these authors to claim that the solar wind, between 0.3 and 1 AU, is inhomogeneous on a scale consistent with the hypothesis that the plume-interplume plasmas, at those distances, still retain their identity. In this work we present preliminary results from an investigation of the solar wind fine structure from Ulysses high latitude observations. To this end, we have analyzed data over several months, during 1994, at times well after Ulysses's last encounter with the Heliospheric Current Sheet, when the spacecraft was at latitudes above 50 degrees. These data refer to high speed wind coming from southern polar coronal holes and are best suited for plume-interplume identification. We have performed a power spectra analysis of typical plasma parameters, to test whether the wind plasma consist of two distinct plasma populations. We also examined data to check whether there is any evidence for an horizontal pressure balance over the hypothesized distinct structures. Our results are discussed and compared with previous findings.

  10. Search for fine scale structures in high latitude solar wind

    NASA Technical Reports Server (NTRS)

    Livi, S.; Parenti, S.; Poletto, G.

    1995-01-01

    About 25 years ago, E. Parker suggested that, as a consequence of the inhomogeneous structure of the corona, the solar wind might consist of adjacent structures with different physical conditions. Since that suggestion was made, the solar wind plasma characteristics have been measured in situ through many experiments, but little has been done to check whether the solar wind shows any evidence for fine scale structures, and, in the affirmative, how far from the Sun these structures persist. A previous work on this subject, by Thieme, Marsch and Schwenn (1990), based on Helios data, lead these authors to claim that the solar wind, between 0.3 and 1 AU, is inhomogeneous on a scale consistent with the hypothesis that the plume-interplume plasmas, at those distances, still retain their identity. In this work we present preliminary results from an investigation of the solar wind fine structure from Ulysses high latitude observations. To this end, we have analyzed data over several months, during 1994, at times well after Ulysses's last encounter with the Heliospheric Current Sheet, when the spacecraft was at latitudes above 50 degrees. These data refer to high speed wind coming from southern polar coronal holes and are best suited for plume-interplume identification. We have performed a power spectra analysis of typical plasma parameters, to test whether the wind plasma consist of two distinct plasma populations. We also examined data to check whether there is any evidence for an horizontal pressure balance over the hypothesized distinct structures. Our results are discussed and compared with previous findings.

  11. Search for fine scale structures in high latitude solar wind

    NASA Technical Reports Server (NTRS)

    Livi, S.; Parenti, S.; Poletto, G.

    1995-01-01

    About 25 years ago, E. Parker suggested that, as a consequence of the inhomogeneous structure of the corona, the solar wind might consist of adjacent structures with different physical conditions. Since that suggestion was made, the solar wind plasma characteristics have been measured in situ through many experiments, but little has been done to check whether the solar wind shows any evidence for fine scale structures, and, in the affirmative, how far from the Sun these structures persist. A previous work on this subject, by Thieme, Marsch and Schwenn (1990), based on Helios data, lead these authors to claim that the solar wind, between 0.3 and 1 AU, is inhomogeneous on a scale consistent with the hypothesis that the plume-interplume plasmas, at those distances, still retain their identity. In this work we present preliminary results from an investigation of the solar wind fine structure from Ulysses high latitude observations. To this end, we have analyzed data over several months, during 1994, at times well after Ulysses's last encounter with the Heliospheric Current Sheet, when the spacecraft was at latitudes above 50 degrees. These data refer to high speed wind coming from southern polar coronal holes and are best suited for plume-interplume identification. We have performed a power spectra analysis of typical plasma parameters, to test whether the wind plasma consist of two distinct plasma populations. We also examined data to check whether there is any evidence for an horizontal pressure balance over the hypothesized distinct structures. Our results are discussed and compared with previous findings.

  12. Modelling Fine Scale Movement Corridors for the Tricarinate Hill Turtle

    NASA Astrophysics Data System (ADS)

    Mondal, I.; Kumar, R. S.; Habib, B.; Talukdar, G.

    2016-06-01

    Habitat loss and the destruction of habitat connectivity can lead to species extinction by isolation of population. Identifying important habitat corridors to enhance habitat connectivity is imperative for species conservation by preserving dispersal pattern to maintain genetic diversity. Circuit theory is a novel tool to model habitat connectivity as it considers habitat as an electronic circuit board and species movement as a certain amount of current moving around through different resistors in the circuit. Most studies involving circuit theory have been carried out at small scales on large ranging animals like wolves or pumas, and more recently on tigers. This calls for a study that tests circuit theory at a large scale to model micro-scale habitat connectivity. The present study on a small South-Asian geoemydid, the Tricarinate Hill-turtle (Melanochelys tricarinata), focuses on habitat connectivity at a very fine scale. The Tricarinate has a small body size (carapace length: 127-175 mm) and home range (8000-15000 m2), with very specific habitat requirements and movement patterns. We used very high resolution Worldview satellite data and extensive field observations to derive a model of landscape permeability at 1 : 2,000 scale to suit the target species. Circuit theory was applied to model potential corridors between core habitat patches for the Tricarinate Hill-turtle. The modelled corridors were validated by extensive ground tracking data collected using thread spool technique and found to be functional. Therefore, circuit theory is a promising tool for accurately identifying corridors, to aid in habitat studies of small species.

  13. Image-Based Fine-Scale Infrastructure Monitoring

    NASA Astrophysics Data System (ADS)

    Detchev, Ivan Denislavov

    Monitoring the physical health of civil infrastructure systems is an important task that must be performed frequently in order to ensure their serviceability and sustainability. Additionally, laboratory experiments where individual system components are tested on the fine-scale level provide essential information during the structural design process. This type of inspection, i.e., measurements of deflections and/or cracks, has traditionally been performed with instrumentation that requires access to, or contact with, the structural element being tested; performs deformation measurements in only one dimension or direction; and/or provides no permanent visual record. To avoid the downsides of such instrumentation, this dissertation proposes a remote sensing approach based on a photogrammetric system capable of three-dimensional reconstruction. The proposed system is low-cost, consists of off-the-shelf components, and is capable of reconstructing objects or surfaces with homogeneous texture. The scientific contributions of this research work address the drawbacks in currently existing literature. Methods for in-situ multi-camera system calibration and system stability analysis are proposed in addition to methods for deflection/displacement monitoring, and crack detection and characterization in three dimensions. The mathematical model for the system calibration is based on a single or multiple reference camera(s) and built-in relative orientation constraints where the interior orientation and the mounting parameters for all cameras are explicitly estimated. The methods for system stability analysis can be used to comprehensively check for the cumulative impact of any changes in the system parameters. They also provide a quantitative measure of this impact on the reconstruction process in terms of image space units. Deflection/displacement monitoring of dynamic surfaces in three dimensions is achieved with the system by performing an innovative sinusoidal fitting

  14. On the Lundgren-Townsend model of turbulent fine scales

    NASA Astrophysics Data System (ADS)

    Pullin, D. I.; Saffman, P. G.

    1993-01-01

    The strained-spiral vortex model of turbulent fines scales given by Lundgren [Phys. Fluids 25, 2193 (1982)] is used to calculate vorticity and velocity-derivative moments for homogeneous isotropic turbulence. A specific form of the relaxing spiral vortex is proposed modeled by a rolling-up vortex layer embedded in a background containing opposite signed vorticity and with zero total circulation at infinity. The numerical values of two dimensionless groups are fixed in order to give a Kolmogorov constant and skewness which are within the range of experiment. This gives the result that the ratio of the ensemble average hyperskewness S2p+1≡ (∂u/∂x)2p+1/[(∂u/∂x)2](2p+1)/2 to the hyperflatness F2p≡(∂u/∂x)2p/[(∂u/∂x)2] p, p=2,3,..., is constant independent of Taylor-Reynolds number Rλ, as is the ratio of the 2pth moment of one component of the vorticity Ω2p≡ω2px/(ω2x)p to F2p. A cutoff in a relevant time integration is then used to eliminate vortex-sheet-induced divergences in the integrals corresponding to ω2px, p=2,3,..., and an assumption is made that the lateral scale of the spiral vortex in the model is the geometric mean of the Taylor and the Kolmogorov microscales. This gives Ω2p=Ω̂2pRλp/2-3/4, F2p=F̂2pRλp/2-3/4 and S2p+1=Ŝ2p+1Rλp/2-3/4, p=2,3,..., with explicit calculation of the numbers Ω̂2p, F̂2p, and Ŝ2p+1. The results of the model are compared with experimental compilation of Van Atta and Antonia [Phys. Fluids 23, 252 (1980)] for F4 and with the isotropic turbulence calculations of Kerr [J. Fluid Mech. 153, 31 (1985)] and of Vincent and Meneguzzi [J. Fluid Mech. 225, 1 (1991)].

  15. Jupiter's Great Red Spot: Fine-scale matches of model vorticity patterns to prevailing cloud patterns

    NASA Astrophysics Data System (ADS)

    Morales-Juberías, Raúl; Dowling, Timothy E.

    2013-07-01

    We report on a set of six new matches between fine-scale features in the vorticity field of a three-dimensional (3D), primitive-equation, finite-difference model of Jupiter's Great Red Spot that includes no clouds or cloud physics, and quasi-permanent structures in reflected visible-band images of the clouds. These add to similar success by Cho et al. (Cho, J., de la Torre Juárez, M., Ingersoll, A.P., Dritschel, D.G. [2001]. J. Geophys. Res. 106, 5099-5106), who earlier captured four characteristic features of the GRS, also reproduced here, using a 3D quasi-geostrophic, cloud-free contour-dynamics model. In that study and this, the key enabling model attribute is sufficient horizontal resolution, rather than the moist-convective and cloud-microphysics processes often required to match the patterns of clouds in terrestrial hurricanes. The only significant feature that these dry models do not capture is the episodic moist-convective plumes seen in the northwest quadrant adjacent to the GRS. We initialize with Jupiter's averaged zonal winds plus an approximately balanced, smooth 3D ellipsoidal anticyclone. The threshold horizontal grid-resolution to obtain the fine-scale matches is approximately Δy/Ld ≲ 0.15, where Δy ≲ 300 km is the meridional grid spacing and Ld ˜ 2000 km the Rossby deformation length. For models with this or finer horizontal resolution, the best correspondence with observations is reached after about six vortex turnaround times from initialization (˜30 Earth days), but good facsimiles of nearly all the studied features appear after only 1.5 turnaround times (˜7-8 days). We conclude that in images of Jupiter, it is not accurate to associate clouds with upward motion, since these dry models reproduce the observed cloud patterns without this association, and indeed the synoptic-scale vertical motions in the model, as well as those deduced from observations, do not at all correspond to the observed cloud patterns. Instead, Jupiter's cloud

  16. Fine-scale morphology of Tubeworm Slump, Monterey Canyon

    NASA Astrophysics Data System (ADS)

    Anderson, K.; Paull, C. K.; Caress, D. W.; Thomas, H.; Gwiazda, R.; Lundsten, E.

    2011-12-01

    Tubeworm Slump is a well-studied deep-sea slide scar on the northern rim of lower Monterey Canyon in approximately 2 km water depth. The interpretation of previous studies suggested that this feature was generated during a single massive slope failure event, which is consistent with the available surface ship multibeam data. High-resolution multibeam bathymetry (vertical precision of 0.15 m and horizontal resolution of 1.0 m) and 2-10 kHz Chirp seismic reflection profiles were recently collected using an autonomous underwater vehicle (AUV) revealing the fine scale morphology and shallow seafloor structure of this feature. The more detailed bathymetry provided by the AUV clearly shows that Tubeworm Slump is a composite of multiple slide events. The data were collected on two 17.5-hour-long dives in 1,850 to 2,650 m water depths and focused on surveying the approximately arcuate shaped scarp, which has a diameter of ~3.2 km and a maximum height of 300 m. An inertial navigation system combined with a Doppler velocity sonar allowed the AUV to fly pre-programmed grids at 3 knots while maintaining an altitude of 50 m above the bottom in this rough topography. The detailed bathymetry shows that the main scarp is actually composed of more than 20 smaller arcuate shaped scarps that are 100 to 400 m across. Crisp lineations, apparently outlining the edges of nearly horizontal beds that have been truncated by slope failures, are obvious within many of these smaller scarps. These lineations are more muted or absent in other places indicating variations in the thicknesses of the sediment drape and implying these small slope failure events are of multiple ages. Variations in the seafloor roughness also characterize distinct regions of the seafloor within the slide scar. On the eastern side of the main scar there is an especially distinctive lobe characterized by numerous blocks of rubble, tongues of debris, and side scarps that apparently cut across the adjacent sediment drape

  17. Fine-scale structure in the far-infrared Milky-Way

    NASA Technical Reports Server (NTRS)

    Waller, William H.; Wall, William F.; Reach, William T.; Varosi, Frank; Ebert, Rick; Laughlin, Gaylin; Boulanger, Francois

    1995-01-01

    This final report summarizes the work performed and which falls into five broad categories: (1) generation of a new data product (mosaics of the far-infrared emission in the Milky Way); (2) acquisition of associated data products at other wavelengths; (3) spatial filtering of the far-infrared mosaics and resulting images of the FIR fine-scale structure; (4) evaluation of the spatially filtered data; (5) characterization of the FIR fine-scale structure in terms of its spatial statistics; and (6) identification of interstellar counterparts to the FIR fine-scale structure.

  18. Fine-scale hydrodynamics influence the spatio-temporal distribution of harbour porpoises at a coastal hotspot

    NASA Astrophysics Data System (ADS)

    Jones, A. R.; Hosegood, P.; Wynn, R. B.; De Boer, M. N.; Butler-Cowdry, S.; Embling, C. B.

    2014-11-01

    The coastal Runnelstone Reef, off southwest Cornwall (UK), is characterised by complex topography and strong tidal flows and is a known high-density site for harbour porpoise (Phocoena phocoena); a European protected species. Using a multidisciplinary dataset including: porpoise sightings from a multi-year land-based survey, Acoustic Doppler Current Profiling (ADCP), vertical profiling of water properties and high-resolution bathymetry; we investigate how interactions between tidal flow and topography drive the fine-scale porpoise spatio-temporal distribution at the site. Porpoise sightings were distributed non-uniformly within the survey area with highest sighting density recorded in areas with steep slopes and moderate depths. Greater numbers of sightings were recorded during strong westward (ebbing) tidal flows compared to strong eastward (flooding) flows and slack water periods. ADCP and Conductivity Temperature Depth (CTD) data identified fine-scale hydrodynamic features, associated with cross-reef tidal flows in the sections of the survey area with the highest recorded densities of porpoises. We observed layered, vertically sheared flows that were susceptible to the generation of turbulence by shear instability. Additionally, the intense, oscillatory near surface currents led to hydraulically controlled flow that transitioned from subcritical to supercritical conditions; indicating that highly turbulent and energetic hydraulic jumps were generated along the eastern and western slopes of the reef. The depression and release of isopycnals in the lee of the reef during cross-reef flows revealed that the flow released lee waves during upslope currents at specific phases of the tidal cycle when the highest sighting rates were recorded. The results of this unique, fine-scale field study provide new insights into specific hydrodynamic features, produced through tidal forcing, that may be important for creating predictable foraging opportunities for porpoises at a

  19. Fine-Scale Structure of Solar Polar Faculae and their relation to Magnetic Patches

    NASA Astrophysics Data System (ADS)

    Suematsu, Y.; Kaithakkal, A. J.

    2014-12-01

    The fine-scale structure and dynamics of solar polar faculae were studied using Hinode/SOT spectro-polarimetric and filtergraphic observations at polar regions. It is revealed that polar magnetic patches of large flux have substructures, with a few small faculae in the much larger patches. It was also found that faculae tend to have higher intrinsic magnetic field strengths compared with the non-facular regions inside the associated magnetic patches. G-band images reveal much thinner facular structures of close to 0.1 arcsec and the faculae appear as a cluster of thin tapered tube-like structures; individual size is about 0.2 x 0.5 arcsec, reaching the maximum closer mid-way to the limb, are likely projected on the limb-side neighboring granules with center-ward dark lanes. Typical lifetime of each facular elements is about five minutes, showing side-way motion during the life. Corresponding bright fine elongated structures are seen in Ca II H, although such structures are more numerous and therefore there does not always exist one-to-one correspondence of Ca II H bright structures with the G-band facular elements. In H-alpha and Na I D line wing, fibril structure emanating limb-ward from the faulae and Ca II H bright regions. Those facts imply that the polar faculae appear in the root of intense vertically-oriented thin magnetic flux tubes which are consistent with the result from the magnetic properties reduced from the spectro-polarimetry. Those results suggest that the Spruit's hot wall effect explains the appearance of faculae in intense vertically oriented flux tube whose formation is dynamically changing.

  20. Quantitative rainfall metrics for comparing volumetric rainfall retrievals to fine scale models

    NASA Astrophysics Data System (ADS)

    Collis, Scott; Tao, Wei-Kuo; Giangrande, Scott; Fridlind, Ann; Theisen, Adam; Jensen, Michael

    2013-04-01

    Precipitation processes play a significant role in the energy balance of convective systems for example, through latent heating and evaporative cooling. Heavy precipitation "cores" can also be a proxy for vigorous convection and vertical motions. However, comparisons between rainfall rate retrievals from volumetric remote sensors with forecast rain fields from high-resolution numerical weather prediction simulations are complicated by differences in the location and timing of storm morphological features. This presentation will outline a series of metrics for diagnosing the spatial variability and statistical properties of precipitation maps produced both from models and retrievals. We include existing metrics such as Contoured by Frequency Altitude Diagrams (Yuter and Houze 1995) and Statistical Coverage Products (May and Lane 2009) and propose new metrics based on morphology, cell and feature based statistics. Work presented focuses on observations from the ARM Southern Great Plains radar network consisting of three agile X-Band radar systems with a very dense coverage pattern and a C Band system providing site wide coverage. By combining multiple sensors resolutions of 250m2 can be achieved, allowing improved characterization of fine-scale features. Analyses compare data collected during the Midlattitude Continental Convective Clouds Experiment (MC3E) with simulations of observed systems using the NASA Unified Weather Research and Forecasting model. May, P. T., and T. P. Lane, 2009: A method for using weather radar data to test cloud resolving models. Meteorological Applications, 16, 425-425, doi:10.1002/met.150, 10.1002/met.150. Yuter, S. E., and R. A. Houze, 1995: Three-Dimensional Kinematic and Microphysical Evolution of Florida Cumulonimbus. Part II: Frequency Distributions of Vertical Velocity, Reflectivity, and Differential Reflectivity. Mon. Wea. Rev., 123, 1941-1963, doi:10.1175/1520-0493(1995)123<1941:TDKAME>2.0.CO;2.

  1. Assessment of fine-scale parameterizations of turbulent dissipation rates near mixing hotspots in the deep ocean

    NASA Astrophysics Data System (ADS)

    Hibiya, Toshiyuki; Furuichi, Naoki; Robertson, Robin

    2012-12-01

    Shear-based and/or strain-based fine-scale parameterizations of turbulent dissipation rates in the deep ocean become erroneous near topographic features where internal wave spectra deviate from Garrett-Munk (GM). Although the Gregg-Henyey-Polzin (GHP) parameterization incorporates this spectral deviation, the applicability remains uncertain. We evaluate “α” and “β” representing the local internal wave energy in the high frequency (2f < ω < N) and low frequency (f < ω < 2f) bands, respectively, scaled by their corresponding values in GM using fine-scale vertical shear and strain simultaneously measured near mixing hotspots. The local internal wave spectra are biased toward higher frequencies (α/β ≫ 1) over rough bathymetry where high frequency internal waves are generated, whereas they are biased toward lower frequencies (α/β ≪ 1) at latitudes where high vertical wavenumber, near-inertial shears are created by parametric subharmonic instabilities. Compared with the shear-based and/or strain-based parameterizations, GHP more accurately estimates turbulent dissipation rates by compensating for deviations from GM.

  2. Fine-scale topography in sensory systems: insights from Drosophila and vertebrates

    PubMed Central

    Kaneko, Takuya; Ye, Bing

    2015-01-01

    To encode the positions of sensory stimuli, sensory circuits form topographic maps in the central nervous system through specific point-to-point connections between pre- and post-synaptic neurons. In vertebrate visual systems, the establishment of topographic maps involves the formation of a coarse topography followed by that of fine-scale topography that distinguishes the axon terminals of neighboring neurons. It is known that intrinsic differences in the form of broad gradients of guidance molecules instruct coarse topography while neuronal activity is required for fine-scale topography. On the other hand, studies in the Drosophila visual system have shown that intrinsic differences in cell adhesion among the axon terminals of neighboring neurons instruct the fine-scale topography. Recent studies on activity-dependent topography in the Drosophila somatosensory system have revealed a role of neuronal activity in creating molecular differences among sensory neurons for establishing fine-scale topography, implicating a conserved principle. Here we review the findings in both Drosophila and vertebrates and propose an integrated model for fine-scale topography. PMID:26091779

  3. Fine-scale topography in sensory systems: insights from Drosophila and vertebrates.

    PubMed

    Kaneko, Takuya; Ye, Bing

    2015-09-01

    To encode the positions of sensory stimuli, sensory circuits form topographic maps in the central nervous system through specific point-to-point connections between pre- and postsynaptic neurons. In vertebrate visual systems, the establishment of topographic maps involves the formation of a coarse topography followed by that of fine-scale topography that distinguishes the axon terminals of neighboring neurons. It is known that intrinsic differences in the form of broad gradients of guidance molecules instruct coarse topography while neuronal activity is required for fine-scale topography. On the other hand, studies in the Drosophila visual system have shown that intrinsic differences in cell adhesion among the axon terminals of neighboring neurons instruct the fine-scale topography. Recent studies on activity-dependent topography in the Drosophila somatosensory system have revealed a role of neuronal activity in creating molecular differences among sensory neurons for establishing fine-scale topography, implicating a conserved principle. Here we review the findings in both Drosophila and vertebrates and propose an integrated model for fine-scale topography.

  4. Computer-Assisted Experiments with Oscillatory Circuits

    ERIC Educational Resources Information Center

    Fernandes, J. C.; Ferraz, A.; Rogalski, M. S.

    2010-01-01

    A basic setup for data acquisition and analysis from an oscillatory circuit is described, with focus on its application as either low-pass, high-pass, band-pass or band-reject frequency filter. A homemade board containing the "RLC" elements allows for the interchange of some of them, in particular, for the easy change of the "R" value, and this…

  5. Downscaling future climate scenarios to fine scales for hydrologic and ecological modeling and analysis

    USGS Publications Warehouse

    Flint, Lorraine E.; Flint, Alan L.

    2012-01-01

    The methodology, which includes a sequence of rigorous analyses and calculations, is intended to reduce the addition of uncertainty to the climate data as a result of the downscaling while providing the fine-scale climate information necessary for ecological analyses. It results in new but consistent data sets for the US at 4 km, the southwest US at 270 m, and California at 90 m and illustrates the utility of fine-scale downscaling to analyses of ecological processes influenced by topographic complexity.

  6. Increase in ocean stratification reduces the aggregation power of fine-scale physical structure

    NASA Astrophysics Data System (ADS)

    Grados, D.; Fablet, R.; Colas, F.; Chaigneau, A.; Echevin, V.; Vasquez, L.; Castillo, R.; Bertrand, A.

    2016-02-01

    The near-surface ocean dynamics includes a variety of processes spanning characteristic horizontal scales from internal waves (IW) to submesoscale and mesoscale features. Recent works based on acoustic data showed that the vertical displacements of the oxycline depth, which separates the well-mixed oxygenated surface layer from the less oxygenated deeper ocean, provide a robust proxy of isopycnals displacements over a wide range of horizontal scales. Using a high-resolution acoustic data set in the Northern Humboldt Current System (NHCS) off Peru, the impact of fine-scale to mesoscale upper ocean dynamics over zooplankton and fish patchiness is investigated. The analysis reveals the existence of distinct features for the fine-scale range below 2-3 km, and clearly points out the existence of intense IW and submesoscale activity over the entire NCHS region. We also address the potential impact of climate variability on fine-scale oases for life that are created by upper ocean turbulence. Indeed stratification changes induced by climate variability could impact both the number and intensity of physical structures and, consequently, distribution patterns of marine life. Using 12 scientific surveys conducted between 2002 and 2011 off Peru, we show that fine-scale structures aggregate fewer organisms when the stratification increases. Climate variability might thus reduces the number and intensity of physical structures, and consequently, size and density of organisms patches with a potential negative impact on resultant trophic interactions.

  7. Lack of sex-biased dispersal promotes fine-scale genetic structure in alpine ungulates

    Treesearch

    Gretchen H. Roffler; Sandra L. Talbot; Gordon Luikart; George K. Sage; Kristy L. Pilgrim; Layne G. Adams; Michael K. Schwartz

    2014-01-01

    Identifying patterns of fine-scale genetic structure in natural populations can advance understanding of critical ecological processes such as dispersal and gene flow across heterogeneous landscapes. Alpine ungulates generally exhibit high levels of genetic structure due to female philopatry and patchy configuration of mountain habitats. We assessed the spatial scale...

  8. A FRAMEWORK FOR FINE-SCALE COMPUTATIONAL FLUID DYNAMICS AIR QUALITY MODELING AND ANALYSIS

    EPA Science Inventory

    This paper discusses a framework for fine-scale CFD modeling that may be developed to complement the present Community Multi-scale Air Quality (CMAQ) modeling system which itself is a computational fluid dynamics model. A goal of this presentation is to stimulate discussions on w...

  9. Methods for Improving Fine-Scale Applications of the WRF-CMAQ Modeling System

    EPA Science Inventory

    Presentation on the work in AMAD to improve fine-scale (e.g. 4km and 1km) WRF-CMAQ simulations. Includes iterative analysis, updated sea surface temperature and snow cover fields, and inclusion of impervious surface information (urban parameterization).

  10. Fine-Scale Population Estimation by 3D Reconstruction of Urban Residential Buildings

    PubMed Central

    Wang, Shixin; Tian, Ye; Zhou, Yi; Liu, Wenliang; Lin, Chenxi

    2016-01-01

    Fine-scale population estimation is essential in emergency response and epidemiological applications as well as urban planning and management. However, representing populations in heterogeneous urban regions with a finer resolution is a challenge. This study aims to obtain fine-scale population distribution based on 3D reconstruction of urban residential buildings with morphological operations using optical high-resolution (HR) images from the Chinese No. 3 Resources Satellite (ZY-3). Specifically, the research area was first divided into three categories when dasymetric mapping was taken into consideration. The results demonstrate that the morphological building index (MBI) yielded better results than built-up presence index (PanTex) in building detection, and the morphological shadow index (MSI) outperformed color invariant indices (CIIT) in shadow extraction and height retrieval. Building extraction and height retrieval were then combined to reconstruct 3D models and to estimate population. Final results show that this approach is effective in fine-scale population estimation, with a mean relative error of 16.46% and an overall Relative Total Absolute Error (RATE) of 0.158. This study gives significant insights into fine-scale population estimation in complicated urban landscapes, when detailed 3D information of buildings is unavailable. PMID:27775670

  11. Fine-scale genetic structure of whitebark pine (Pinus albicaulis) associations with watershed and growth form

    Treesearch

    Deborah L. Rogers; Constance I. Millar; Robert D. Westfall

    1999-01-01

    The fine-scale genetic structure of a subalpine conifer, whitebark pine (Pinus albicaulis Engelm.), was studied at nested geographic levels from watershed to adjacent stems in the eastern Sierra Nevada Range of California. A combination of several characteristics contributed to unpredicted genetic structure in this species. This includes being one of...

  12. IMPLEMENTATION OF AN URBAN CANOPY PARAMETERIZATION FOR FINE-SCALE SIMULATIONS

    EPA Science Inventory

    The Pennsylvania State University/National Center for Atmospheric Research Mesoscale Model (MM5) (Grell et al. 1994) has been modified to include an urban canopy parameterization (UCP) for fine-scale urban simulations ( 1 - km horizontal grid spacing ). The UCP accounts for dr...

  13. Fine-scale habitat characteristics related to occupancy of the Yosemite Toad, Anaxyrus canorus

    Treesearch

    Christina T. Liang; Robert L. Grasso; Julie J. Nelson-Paul; Kim E. Vincent; Amy J. Lind

    2017-01-01

    Fine-scale habitat information can provide insight into species occupancy and persistence that is not apparent at the landscape-scale. Such information is particularly important for rare species that are experiencing population declines, such as the threatened Yosemite Toad (Anaxyrus canorus). Our study examined differences in physical...

  14. Fine-scale population structure, inbreeding risk and avoidance in a wild insect population.

    PubMed

    Bretman, Amanda; Rodríguez-Muñoz, Rolando; Walling, Craig; Slate, Jon; Tregenza, Tom

    2011-07-01

    The ecological and evolutionary importance of fine-scale genetic structure within populations is increasingly appreciated. However, available data are largely restricted to wild vertebrates and eusocial insects. In addition, there is the expectation that most insects tend to have such large- and high-density populations and are so mobile that they are unlikely to face inbreeding risks through fine-scale population structuring. This has made the growing body of evidence for inbreeding avoidance in insects and its implication in mating systems evolution somewhat enigmatic. We present a 4-year study of a natural population of field crickets. Using detailed video monitoring combined with genotyping, we track the movement of all adults within the population and investigate genetic structure at a fine scale. We find some evidence for relatives being found in closer proximity, both across generations and within a single breeding season. Whilst incestuous matings are not avoided, population inbreeding is low, suggesting that mating is close to random and the limited fine-scale structure does not create significant inbreeding risk. Hence, there is little evidence for selective pressures associated with the evolution of inbreeding avoidance mechanisms in a closely related species.

  15. A FRAMEWORK FOR FINE-SCALE COMPUTATIONAL FLUID DYNAMICS AIR QUALITY MODELING AND ANALYSIS

    EPA Science Inventory

    This paper discusses a framework for fine-scale CFD modeling that may be developed to complement the present Community Multi-scale Air Quality (CMAQ) modeling system which itself is a computational fluid dynamics model. A goal of this presentation is to stimulate discussions on w...

  16. Clonal growth and fine-scale genetic structure in tanoak (Notholithocarpus densiflorus: Fagaceae)

    Treesearch

    Richard S. Dodd; Wasima Mayer; Alejandro Nettel; Zara. Afzal-Rafii

    2013-01-01

    The combination of sprouting and reproduction by seed can have important consequences on fine-scale spatial distribution of genetic structure (SGS). SGS is an important consideration for species’ restoration because it determines the minimum distance among seed trees to maximize genetic diversity while not prejudicing locally adapted genotypes. Local environmental...

  17. 75 FR 60407 - Gulf of the Farallones National Marine Sanctuary Permit Application Project Titled: Fine Scale...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-09-30

    ... Application Project Titled: Fine Scale, Long-Term Tracking of Adult White Sharks AGENCY: Office of National... attraction and approach of white sharks in the sanctuary. The purpose of the proposed study is to improve our knowledge of the full migratory cycle of white sharks by attaching location transmitters to up to eleven (11...

  18. CFD MODELING OF FINE SCALE FLOW AND TRANSPORT IN THE HOUSTON METROPOLITAN AREA, TEXAS

    EPA Science Inventory

    Fine scale modeling of flows and air quality in Houston, Texas is being performed; the use of computational fluid dynamics (CFD) modeling is being applied to investigate the influence of morphologic structures on the within-grid transport and dispersion of sources in grid models ...

  19. Fine scale variations of surface water chemistry in an ephemeral to perennial drainage network

    Treesearch

    Margaret A. Zimmer; Scott W. Bailey; Kevin J. McGuire; Thomas D. Bullen

    2013-01-01

    Although temporal variation in headwater stream chemistry has long been used to document baseline conditions and response to environmental drivers, less attention is paid to fine scale spatial variations that could yield clues to processes controlling stream water sources. We documented spatial and temporal variation in water composition in a headwater catchment (41 ha...

  20. IMPLEMENTATION OF AN URBAN CANOPY PARAMETERIZATION FOR FINE-SCALE SIMULATIONS

    EPA Science Inventory

    The Pennsylvania State University/National Center for Atmospheric Research Mesoscale Model (MM5) (Grell et al. 1994) has been modified to include an urban canopy parameterization (UCP) for fine-scale urban simulations ( 1 - km horizontal grid spacing ). The UCP accounts for dr...

  1. Methods for Improving Fine-Scale Applications of the WRF-CMAQ Modeling System

    EPA Science Inventory

    Presentation on the work in AMAD to improve fine-scale (e.g. 4km and 1km) WRF-CMAQ simulations. Includes iterative analysis, updated sea surface temperature and snow cover fields, and inclusion of impervious surface information (urban parameterization).

  2. CFD MODELING OF FINE SCALE FLOW AND TRANSPORT IN THE HOUSTON METROPOLITAN AREA, TEXAS

    EPA Science Inventory

    Fine scale modeling of flows and air quality in Houston, Texas is being performed; the use of computational fluid dynamics (CFD) modeling is being applied to investigate the influence of morphologic structures on the within-grid transport and dispersion of sources in grid models ...

  3. Fine-Scale Habitat Segregation between Two Ecologically Similar Top Predators

    PubMed Central

    Palomares, Francisco; Fernández, Néstor; Roques, Severine; Chávez, Cuauhtemoc; Silveira, Leandro; Keller, Claudia; Adrados, Begoña

    2016-01-01

    Similar, coexisting species often segregate along the spatial ecological axis. Here, we examine if two top predators (jaguars and pumas) present different fine-scale habitat use in areas of coexistence, and discuss if the observed pattern can be explained by the risk of interference competition between them. Interference competition theory predicts that pumas should avoid habitats or areas used by jaguars (the dominant species), and as a consequence should present more variability of niche parameters across study areas. We used non-invasive genetic sampling of faeces in 12 different areas and sensor satellite fine-scale habitat indices to answer these questions. Meta-analysis confirmed differences in fine-scale habitat use between jaguars and pumas. Furthermore, average marginality of the realized niches of pumas was more variable than those of jaguars, and tolerance (a measure of niche breadth) was on average 2.2 times higher in pumas than in jaguars, as expected under the interference competition risk hypothesis. The use of sensor satellite fine-scale habitat indices allowed the detection of subtle differences in the environmental characteristics of the habitats used by these two similar top predators, which, as a rule, until now were recorded using the same general habitat types. The detection of fine spatial segregation between these two top predators was scale-dependent. PMID:27187596

  4. Genome-Wide Fine-Scale Recombination Rate Variation in Drosophila melanogaster

    PubMed Central

    Song, Yun S.

    2012-01-01

    Estimating fine-scale recombination maps of Drosophila from population genomic data is a challenging problem, in particular because of the high background recombination rate. In this paper, a new computational method is developed to address this challenge. Through an extensive simulation study, it is demonstrated that the method allows more accurate inference, and exhibits greater robustness to the effects of natural selection and noise, compared to a well-used previous method developed for studying fine-scale recombination rate variation in the human genome. As an application, a genome-wide analysis of genetic variation data is performed for two Drosophila melanogaster populations, one from North America (Raleigh, USA) and the other from Africa (Gikongoro, Rwanda). It is shown that fine-scale recombination rate variation is widespread throughout the D. melanogaster genome, across all chromosomes and in both populations. At the fine-scale, a conservative, systematic search for evidence of recombination hotspots suggests the existence of a handful of putative hotspots each with at least a tenfold increase in intensity over the background rate. A wavelet analysis is carried out to compare the estimated recombination maps in the two populations and to quantify the extent to which recombination rates are conserved. In general, similarity is observed at very broad scales, but substantial differences are seen at fine scales. The average recombination rate of the X chromosome appears to be higher than that of the autosomes in both populations, and this pattern is much more pronounced in the African population than the North American population. The correlation between various genomic features—including recombination rates, diversity, divergence, GC content, gene content, and sequence quality—is examined using the wavelet analysis, and it is shown that the most notable difference between D. melanogaster and humans is in the correlation between recombination and

  5. Assessment of fine-scale parameterizations of turbulent dissipation rates in the Southern Ocean

    NASA Astrophysics Data System (ADS)

    Takahashi, A.; Hibiya, T.

    2016-12-01

    To sustain the global overturning circulation, more mixing is required in the ocean than has been observed. The most likely candidates for this missing mixing are breaking of wind-induced near-inertial waves and bottom-generated internal lee waves in the sparsely observed Southern Ocean. Nevertheless, there is a paucity of direct microstructure measurements in the Southern Ocean where energy dissipation rates have been estimated mostly using fine-scale parameterizations. In this study, we assess the validity of the existing fine-scale parameterizations in the Antarctic Circumpolar Current (ACC) region using the data obtained from simultaneous full-depth measurements of micro-scale turbulence and fine-scale shear/strain carried out south of Australia during January 17 to February 2, 2016. Although the fine-scale shear/strain ratio (Rω) is close to the Garrett-Munk (GM) value at the station north of Subtropical Front, the values of Rω at the stations south of Subantarctic Front well exceed the GM value, suggesting that the local internal wave spectra are significantly biased to lower frequencies. We find that not all of the observed energy dissipation rates at these locations are well predicted using Gregg-Henyey-Polzin (GHP; Gregg et al., 2003) and Ijichi-Hibiya (IH; Ijichi and Hibiya, 2015) parameterizations, both of which take into account the spectral distortion in terms of Rω; energy dissipation rates at some locations are obviously overestimated by GHP and IH, although only the strain-based Wijesekera (Wijesekera et al., 1993) parameterization yields fairly good predictions. One possible explanation for this result is that a significant portion of the observed shear variance at these locations might be attributed to kinetic-energy-dominant small-scale eddies associated with the ACC, so that fine-scale strain rather than Rω becomes a more appropriate parameter to characterize the actual internal wave field.

  6. Oscillatory Correlates of Visual Consciousness

    PubMed Central

    Gallotto, Stefano; Sack, Alexander T.; Schuhmann, Teresa; de Graaf, Tom A.

    2017-01-01

    Conscious experiences are linked to activity in our brain: the neural correlates of consciousness (NCC). Empirical research on these NCCs covers a wide range of brain activity signals, measures, and methodologies. In this paper, we focus on spontaneous brain oscillations; rhythmic fluctuations of neuronal (population) activity which can be characterized by a range of parameters, such as frequency, amplitude (power), and phase. We provide an overview of oscillatory measures that appear to correlate with conscious perception. We also discuss how increasingly sophisticated techniques allow us to study the causal role of oscillatory activity in conscious perception (i.e., ‘entrainment’). This review of oscillatory correlates of consciousness suggests that, for example, activity in the alpha-band (7–13 Hz) may index, or even causally support, conscious perception. But such results also showcase an increasingly acknowledged difficulty in NCC research; the challenge of separating neural activity necessary for conscious experience to arise (prerequisites) from neural activity underlying the conscious experience itself (substrates) or its results (consequences). PMID:28736543

  7. Oscillatory Correlates of Visual Consciousness.

    PubMed

    Gallotto, Stefano; Sack, Alexander T; Schuhmann, Teresa; de Graaf, Tom A

    2017-01-01

    Conscious experiences are linked to activity in our brain: the neural correlates of consciousness (NCC). Empirical research on these NCCs covers a wide range of brain activity signals, measures, and methodologies. In this paper, we focus on spontaneous brain oscillations; rhythmic fluctuations of neuronal (population) activity which can be characterized by a range of parameters, such as frequency, amplitude (power), and phase. We provide an overview of oscillatory measures that appear to correlate with conscious perception. We also discuss how increasingly sophisticated techniques allow us to study the causal role of oscillatory activity in conscious perception (i.e., 'entrainment'). This review of oscillatory correlates of consciousness suggests that, for example, activity in the alpha-band (7-13 Hz) may index, or even causally support, conscious perception. But such results also showcase an increasingly acknowledged difficulty in NCC research; the challenge of separating neural activity necessary for conscious experience to arise (prerequisites) from neural activity underlying the conscious experience itself (substrates) or its results (consequences).

  8. On velocity gradient dynamics and fine-scale structure: experiments support DNS and models

    NASA Astrophysics Data System (ADS)

    Lawson, John; Dawson, James

    2015-11-01

    The fine scales of turbulence are embodied by statistics of velocity gradients. In solving exact equations for their evolution, the challenge is to specify how the pressure Hessian acts. This is determined by the footprints that ``structures'' of enstrophy and strain leave in conditional average pressure fields. We use direct and approximate conditional averaging methods to extract this structure from different turbulence datasets: a direct numerical simulation and a unique scanning tomography experiment in a ``French washing machine''. Direct comparisons between simulation and experiment show the structure and resulting dynamics are in excellent, quantitative agreement. This evidence supports existing modelling approaches and provides insights towards their refinement. Moreover, it demonstrates the dynamical significance and the reproducibility of fine-scale structure.

  9. INTRINSIC FINE-SCALE STRUCTURE IN COMPLEX MATERIALS: BEYOND GLOBAL CRYSTALLOGRAPHIC ANALYSIS

    SciTech Connect

    A. MIGLIORI; ET AL

    2000-12-01

    Many important classes of materials owe their interesting properties to structures and patterns produced by local atomic deviations from ideal crystallographic positions. The pattern scale may vary from a few atomic spacings to many microns. In a macroscopic sample these deviations may still average to an ideal lattice while retaining the intrinsic fine-scale structures, or a phase transition may create a pattern of variants of a new crystallographic structure. We have carried out experiments on the formation of fine-scale structures in a range of materials, particularly those produced by phase transitions. We have used Resonant Ultrasound Spectroscopy for elastic properties and dissipation, neutron pair-distribution function, and electronic transport measurements to characterize samples. We have carried out extensive dynamical modeling based on Ginzberg-Landau formalisms to simulate the development and appearance of the structures. Our results highlight the importance of long-range strain fields and the intrinsic unstable equilibrium features of the materials studied.

  10. The Fine-Scale Functional Correlation of Striate Cortex in Sighted and Blind People

    PubMed Central

    Butt, Omar H.; Benson, Noah C.; Datta, Ritobrato

    2013-01-01

    To what extent are spontaneous neural signals within striate cortex organized by vision? We examined the fine-scale pattern of striate cortex correlations within and between hemispheres in rest-state BOLD fMRI data from sighted and blind people. In the sighted, we find that corticocortico correlation is well modeled as a Gaussian point-spread function across millimeters of striate cortical surface, rather than degrees of visual angle. Blindness produces a subtle change in the pattern of fine-scale striate correlations between hemispheres. Across participants blind before the age of 18, the degree of pattern alteration covaries with the strength of long-range correlation between left striate cortex and Broca's area. This suggests that early blindness exchanges local, vision-driven pattern synchrony of the striate cortices for long-range functional correlations potentially related to cross-modal representation. PMID:24107953

  11. Predictive Modelling to Identify Near-Shore, Fine-Scale Seabird Distributions during the Breeding Season

    PubMed Central

    Warwick-Evans, Victoria C.; Atkinson, Philip W.; Robinson, Leonie A.; Green, Jonathan A.

    2016-01-01

    During the breeding season seabirds are constrained to coastal areas and are restricted in their movements, spending much of their time in near-shore waters either loafing or foraging. However, in using these areas they may be threatened by anthropogenic activities such as fishing, watersports and coastal developments including marine renewable energy installations. Although many studies describe large scale interactions between seabirds and the environment, the drivers behind near-shore, fine-scale distributions are not well understood. For example, Alderney is an important breeding ground for many species of seabird and has a diversity of human uses of the marine environment, thus providing an ideal location to investigate the near-shore fine-scale interactions between seabirds and the environment. We used vantage point observations of seabird distribution, collected during the 2013 breeding season in order to identify and quantify some of the environmental variables affecting the near-shore, fine-scale distribution of seabirds in Alderney’s coastal waters. We validate the models with observation data collected in 2014 and show that water depth, distance to the intertidal zone, and distance to the nearest seabird nest are key predictors in the distribution of Alderney’s seabirds. AUC values for each species suggest that these models perform well, although the model for shags performed better than those for auks and gulls. While further unexplained underlying localised variation in the environmental conditions will undoubtedly effect the fine-scale distribution of seabirds in near-shore waters we demonstrate the potential of this approach in marine planning and decision making. PMID:27031616

  12. Data, data everywhere: detecting spatial patterns in fine-scale ecological information collected across a continent

    Treesearch

    Kevin M. Potter; Frank H. Koch; Christopher M. Oswalt; Basil V. Iannone

    2016-01-01

    Context Fine-scale ecological data collected across broad regions are becoming increasingly available. Appropriate geographic analyses of these data can help identify locations of ecological concern. Objectives We present one such approach, spatial association of scalable hexagons (SASH), whichidentifies locations where ecological phenomena occur at greater...

  13. Fine-Scale Focal DTAG Behavioral Study in the Gulf of Maine

    DTIC Science & Technology

    2011-09-30

    Several humpback whale stocks are showing stronger recovery than right whales , despite overlapping habitat usage on the feeding grounds in the...goal of this project is to obtain fine-scale behavior data from two endangered baleen whale species, the humpback whale (Megaptera novaengliae) and...tag data to: 1) determine the diel trends in dive profiles and horizontal movement patterns for tagged humpback and right whales on the Stellwagen

  14. Predictive Modelling to Identify Near-Shore, Fine-Scale Seabird Distributions during the Breeding Season.

    PubMed

    Warwick-Evans, Victoria C; Atkinson, Philip W; Robinson, Leonie A; Green, Jonathan A

    2016-01-01

    During the breeding season seabirds are constrained to coastal areas and are restricted in their movements, spending much of their time in near-shore waters either loafing or foraging. However, in using these areas they may be threatened by anthropogenic activities such as fishing, watersports and coastal developments including marine renewable energy installations. Although many studies describe large scale interactions between seabirds and the environment, the drivers behind near-shore, fine-scale distributions are not well understood. For example, Alderney is an important breeding ground for many species of seabird and has a diversity of human uses of the marine environment, thus providing an ideal location to investigate the near-shore fine-scale interactions between seabirds and the environment. We used vantage point observations of seabird distribution, collected during the 2013 breeding season in order to identify and quantify some of the environmental variables affecting the near-shore, fine-scale distribution of seabirds in Alderney's coastal waters. We validate the models with observation data collected in 2014 and show that water depth, distance to the intertidal zone, and distance to the nearest seabird nest are key predictors in the distribution of Alderney's seabirds. AUC values for each species suggest that these models perform well, although the model for shags performed better than those for auks and gulls. While further unexplained underlying localised variation in the environmental conditions will undoubtedly effect the fine-scale distribution of seabirds in near-shore waters we demonstrate the potential of this approach in marine planning and decision making.

  15. Parallelization of fine-scale computation in Agile Multiscale Modelling Methodology

    NASA Astrophysics Data System (ADS)

    Macioł, Piotr; Michalik, Kazimierz

    2016-10-01

    Nowadays, multiscale modelling of material behavior is an extensively developed area. An important obstacle against its wide application is high computational demands. Among others, the parallelization of multiscale computations is a promising solution. Heterogeneous multiscale models are good candidates for parallelization, since communication between sub-models is limited. In this paper, the possibility of parallelization of multiscale models based on Agile Multiscale Methodology framework is discussed. A sequential, FEM based macroscopic model has been combined with concurrently computed fine-scale models, employing a MatCalc thermodynamic simulator. The main issues, being investigated in this work are: (i) the speed-up of multiscale models with special focus on fine-scale computations and (ii) on decreasing the quality of computations enforced by parallel execution. Speed-up has been evaluated on the basis of Amdahl's law equations. The problem of `delay error', rising from the parallel execution of fine scale sub-models, controlled by the sequential macroscopic sub-model is discussed. Some technical aspects of combining third-party commercial modelling software with an in-house multiscale framework and a MPI library are also discussed.

  16. Multipoint MMS observations of fine-scale SAPS structure in the inner magnetosphere

    NASA Astrophysics Data System (ADS)

    Erickson, P. J.; Matsui, H.; Foster, J. C.; Torbert, R. B.; Ergun, R.; Khotyaintsev, Y. V.; Lindqvist, P. A.; Argall, M. R.; Farrugia, C. J.; Paulson, K. W.; Strangeway, R. J.; Magnes, W.

    2016-12-01

    We present detailed observations of dynamic, fine-scale inner magnetosphere-ionosphere coupling at ˜3.9 Re in the Region 2 Birkeland field-aligned current (FAC). We find that observed electrodynamic spatial/temporal scales are primarily characteristic of magnetically mapped ionospheric structure. On 15 September 2015, conjugate Magnetospheric Multiscale (MMS) spacecraft and Millstone Hill radar observations show plasmasphere boundary region subauroral polarization stream (SAPS) electric fields at L = 4.0-4.2 near 21 MLT. MMS observations reveal high-altitude ˜1 mV/m fine-scale radial and azimuthal electric field perturbations over ≤0.15 L with high spatial coherence over ≥2-3 min and show outward motion within a broader FAC of ˜0.12 μA/m2. Our analysis shows that MMS electric field fluctuations are most likely reflective of SAPS ionospheric structure at scales of ˜22 km and with ionospheric closure of small-scale filamentary FAC perturbations. The results highlight the ionosphere's importance in regulating fine-scale magnetosphere-ionosphere structure.

  17. Fine scale genetic structure in the wild ancestor of maize (Zea mays ssp. parviglumis).

    PubMed

    Van Heerwaarden, Joost; Ross-Ibarra, Jeffrey; Doebley, John; Glaubitz, Jeffrey C; González, Jose De Jesús Sánchez; Gaut, Brandon S; Eguiarte, Luis E

    2010-03-01

    Analysis of fine scale genetic structure in continuous populations of outcrossing plant species has traditionally been limited by the availability of sufficient markers. We used a set of 468 SNPs to characterize fine-scale genetic structure within and between two dense stands of the wild ancestor of maize, teosinte (Zea mays ssp. parviglumis). Our analyses confirmed that teosinte is highly outcrossing and showed little population structure over short distances. We found that the two populations were clearly genetically differentiated, although the actual level of differentiation was low. Spatial autocorrelation of relatedness was observed within both sites but was somewhat stronger in one of the populations. Using principal component analysis, we found evidence for significant local differentiation in the population with stronger spatial autocorrelation. This differentiation was associated with pronounced shifts in the first two principal components along the field. These shifts corresponded to changes in allele frequencies, potentially due to local topographical features. There was little evidence for selection at individual loci as a contributing factor to differentiation. Our results demonstrate that significant local differentiation may, but need not, co-occur with spatial autocorrelation of relatedness. The present study represents one of the most detailed analyses of local genetic structure to date and provides a benchmark for future studies dealing with fine scale patterns of genetic diversity in natural plant populations.

  18. FINE-SCALE STRUCTURES OF FLUX ROPES TRACKED BY ERUPTING MATERIAL

    SciTech Connect

    Li Ting; Zhang Jun E-mail: zjun@nao.cas.cn

    2013-06-20

    We present Solar Dynamics Observatory observations of two flux ropes tracked out by material from a surge and a failed filament eruption on 2012 July 29 and August 4, respectively. For the first event, the interaction between the erupting surge and a loop-shaped filament in the east seems to 'peel off' the filament and add bright mass into the flux rope body. The second event is associated with a C-class flare that occurs several minutes before the filament activation. The two flux ropes are, respectively, composed of 85 {+-} 12 and 102 {+-} 15 fine-scale structures, with an average width of about 1.''6. Our observations show that two extreme ends of the flux rope are rooted in opposite polarity fields and each end is composed of multiple footpoints (FPs) of fine-scale structures. The FPs of the fine-scale structures are located at network magnetic fields, with magnetic fluxes from 5.6 Multiplication-Sign 10{sup 18} Mx to 8.6 Multiplication-Sign 10{sup 19} Mx. Moreover, almost half of the FPs show converging motion of smaller magnetic structures over 10 hr before the appearance of the flux rope. By calculating the magnetic fields of the FPs, we deduce that the two flux ropes occupy at least 4.3 Multiplication-Sign 10{sup 20} Mx and 7.6 Multiplication-Sign 10{sup 20} Mx magnetic fluxes, respectively.

  19. Multipoint MMS observations of fine-scale SAPS structure in the inner magnetosphere

    NASA Astrophysics Data System (ADS)

    Erickson, P. J.; Matsui, H.; Foster, J. C.; Torbert, R. B.; Ergun, R. E.; Khotyaintsev, Yu. V.; Lindqvist, P.-A.; Argall, M. R.; Farrugia, C. J.; Paulson, K. W.; Strangeway, R. J.; Magnes, W.

    2016-07-01

    We present detailed observations of dynamic, fine-scale inner magnetosphere-ionosphere coupling at ˜3.9 RE in the Region 2 Birkeland field-aligned current (FAC). We find that observed electrodynamic spatial/temporal scales are primarily characteristic of magnetically mapped ionospheric structure. On 15 September 2015, conjugate Magnetospheric Multiscale (MMS) spacecraft and Millstone Hill radar observations show plasmasphere boundary region subauroral polarization stream (SAPS) electric fields at L = 4.0-4.2 near 21 MLT. MMS observations reveal high-altitude ˜1 mV/m fine-scale radial and azimuthal electric field perturbations over ≤0.15 L with high spatial coherence over ≥2-3 min and show outward motion within a broader FAC of ˜0.12 μA/m2. Our analysis shows that MMS electric field fluctuations are most likely reflective of SAPS ionospheric structure at scales of ˜22 km and with ionospheric closure of small-scale filamentary FAC perturbations. The results highlight the ionosphere's importance in regulating fine-scale magnetosphere-ionosphere structure.

  20. Fine-scale processes regulate the response of extreme events to global climate change

    PubMed Central

    Diffenbaugh, Noah S.; Pal, Jeremy S.; Trapp, Robert J.; Giorgi, Filippo

    2005-01-01

    We find that extreme temperature and precipitation events are likely to respond substantially to anthropogenically enhanced greenhouse forcing and that fine-scale climate system modifiers are likely to play a critical role in the net response. At present, such events impact a wide variety of natural and human systems, and future changes in their frequency and/or magnitude could have dramatic ecological, economic, and sociological consequences. Our results indicate that fine-scale snow albedo effects influence the response of both hot and cold events and that peak increases in extreme hot events are amplified by surface moisture feedbacks. Likewise, we find that extreme precipitation is enhanced on the lee side of rain shadows and over coastal areas dominated by convective precipitation. We project substantial, spatially heterogeneous increases in both hot and wet events over the contiguous United States by the end of the next century, suggesting that consideration of fine-scale processes is critical for accurate assessment of local- and regional-scale vulnerability to climate change. PMID:16236722

  1. European Invasion of North American Pinus strobus at Large and Fine Scales: High Genetic Diversity and Fine-Scale Genetic Clustering over Time in the Adventive Range

    PubMed Central

    Mandák, Bohumil; Hadincová, Věroslava; Mahelka, Václav; Wildová, Radka

    2013-01-01

    Background North American Pinus strobus is a highly invasive tree species in Central Europe. Using ten polymorphic microsatellite loci we compared various aspects of the large-scale genetic diversity of individuals from 30 sites in the native distribution range with those from 30 sites in the European adventive distribution range. To investigate the ascertained pattern of genetic diversity of this intercontinental comparison further, we surveyed fine-scale genetic diversity patterns and changes over time within four highly invasive populations in the adventive range. Results Our data show that at the large scale the genetic diversity found within the relatively small adventive range in Central Europe, surprisingly, equals the diversity found within the sampled area in the native range, which is about thirty times larger. Bayesian assignment grouped individuals into two genetic clusters separating North American native populations from the European, non-native populations, without any strong genetic structure shown over either range. In the case of the fine scale, our comparison of genetic diversity parameters among the localities and age classes yielded no evidence of genetic diversity increase over time. We found that SGS differed across age classes within the populations under study. Old trees in general completely lacked any SGS, which increased over time and reached its maximum in the sapling stage. Conclusions Based on (1) the absence of difference in genetic diversity between the native and adventive ranges, together with the lack of structure in the native range, and (2) the lack of any evidence of any temporal increase in genetic diversity at four highly invasive populations in the adventive range, we conclude that population amalgamation probably first happened in the native range, prior to introduction. In such case, there would have been no need for multiple introductions from previously isolated populations, but only several introductions from

  2. Binary Oscillatory Crossflow Electrophoresis

    NASA Technical Reports Server (NTRS)

    Molloy, Richard F.; Gallagher, Christopher T.; Leighton, David T., Jr.

    1996-01-01

    We present preliminary results of our implementation of a novel electrophoresis separation technique: Binary Oscillatory Cross flow Electrophoresis (BOCE). The technique utilizes the interaction of two driving forces, an oscillatory electric field and an oscillatory shear flow, to create an active binary filter for the separation of charged species. Analytical and numerical studies have indicated that this technique is capable of separating proteins with electrophoretic mobilities differing by less than 10%. With an experimental device containing a separation chamber 20 cm long, 5 cm wide, and 1 mm thick, an order of magnitude increase in throughput over commercially available electrophoresis devices is theoretically possible.

  3. Theta-band oscillatory activity differs between gamblers and nongamblers comorbid with attention-deficit hyperactivity disorder in a probabilistic reward-learning task.

    PubMed

    Abouzari, Mehdi; Oberg, Scott; Tata, Matthew

    2016-10-01

    Problemgambling is thought to be comorbid with attention-deficit hyperactivity disorder (ADHD). We tested whether gamblers and ADHD patients exhibit similar reward-related brain activity in response to feedback in a gambling task. A series of brain electrical responses can be observed in the electroencephalogram (EEG) and the stimulus-locked event-related potentials (ERP), when participants in a gambling task are given feedback regardless of winning or losing the previous bet. Here, we used a simplified computerized version of the Iowa Gambling Task (IGT) to assess differences in reinforcement-driven choice adaptation between unmedicated ADHD patients with or without problem gambling traits and contrasted with a sex- and age-matched control group. EEG was recorded from the participants while they were engaged in the task which contained two choice options with different net payouts and win/loss probabilities. Learning trend which shows the ability to acquire and use knowledge of the reward outcomes to obtain a positive financial outcome was not observed in ADHD gamblers versus nongamblers. Induced theta-band (4-8Hz) power over frontal cortex was significantly higher in gamblers versus nongamblers in all different high-risk/low-risk win/lose conditions. Whereas induced low alpha (9-11Hz) power at frontal electrodes could only differentiate high-risk lose between gamblers and nongamblers but not the other three conditions between the two groups. The results indicate that ADHD nongamblers do not share with problem gamblers underlying deficits in reward learning. These pilot data highlight the need for studies of ADHD in gambling to elucidate how motivational states are represented during feedback processing.

  4. L-theanine and caffeine in combination affect human cognition as evidenced by oscillatory alpha-band activity and attention task performance.

    PubMed

    Kelly, Simon P; Gomez-Ramirez, Manuel; Montesi, Jennifer L; Foxe, John J

    2008-08-01

    Recent neuropharmacological research has suggested that certain constituents of tea may have modulatory effects on brain state. The bulk of this research has focused on either L-theanine or caffeine ingested alone (mostly the latter) and has been limited to behavioral testing, subjective rating, or neurophysiological assessments during resting. Here, we investigated the effects of both L-theanine and caffeine, ingested separately or together, on behavioral and electrophysiological indices of tonic (background) and phasic (event-related) visuospatial attentional deployment. Subjects underwent 4 d of testing, ingesting either placebo, 100 mg of L-theanine, 50 mg of caffeine, or these treatments combined. The task involved cued shifts of attention to the left or right visual hemifield in anticipation of an imperative stimulus requiring discrimination. In addition to behavioral measures, we examined overall, tonic attentional focus as well as phasic, cue-dependent anticipatory attentional biasing, as indexed by scalp-recorded alpha-band (8-14 Hz) activity. We found an increase in hit rate and target discriminability (d') for the combined treatment relative to placebo, and an increase in d' but not hit rate for caffeine alone, whereas no effects were detected for L-theanine alone. Electrophysiological results did not show increased differential biasing in phasic alpha across hemifields but showed lower overall tonic alpha power in the combined treatment, similar to previous findings at a larger dosage of L-theanine alone. This may signify a more generalized tonic deployment of attentional resources to the visual modality and may underlie the facilitated behavioral performance on the combined ingestion of these 2 major constituents of tea.

  5. Fine-scale spatial genetic structure of common and declining bumble bees across an agricultural landscape.

    PubMed

    Dreier, Stephanie; Redhead, John W; Warren, Ian A; Bourke, Andrew F G; Heard, Matthew S; Jordan, William C; Sumner, Seirian; Wang, Jinliang; Carvell, Claire

    2014-07-01

    Land-use changes have threatened populations of many insect pollinators, including bumble bees. Patterns of dispersal and gene flow are key determinants of species' ability to respond to land-use change, but have been little investigated at a fine scale (<10 km) in bumble bees. Using microsatellite markers, we determined the fine-scale spatial genetic structure of populations of four common Bombus species (B. terrestris, B. lapidarius, B. pascuorum and B. hortorum) and one declining species (B. ruderatus) in an agricultural landscape in Southern England, UK. The study landscape contained sown flower patches representing agri-environment options for pollinators. We found that, as expected, the B. ruderatus population was characterized by relatively low heterozygosity, number of alleles and colony density. Across all species, inbreeding was absent or present but weak (FIS  = 0.01-0.02). Using queen genotypes reconstructed from worker sibships and colony locations estimated from the positions of workers within these sibships, we found that significant isolation by distance was absent in B. lapidarius, B. hortorum and B. ruderatus. In B. terrestris and B. pascuorum, it was present but weak; for example, in these two species, expected relatedness of queens founding colonies 1 m apart was 0.02. These results show that bumble bee populations exhibit low levels of spatial genetic structure at fine spatial scales, most likely because of ongoing gene flow via widespread queen dispersal. In addition, the results demonstrate the potential for agri-environment scheme conservation measures to facilitate fine-scale gene flow by creating a more even distribution of suitable habitats across landscapes. © 2014 The Authors. Molecular Ecology Published by John Wiley & Sons Ltd.

  6. Fine-Scale Habitat Heterogeneity Influences Occupancy in Terrestrial Mammals in a Temperate Region of Australia

    PubMed Central

    Stirnemann, Ingrid; Mortelliti, Alessio; Gibbons, Philip; Lindenmayer, David B.

    2015-01-01

    Vegetation heterogeneity is an inherent feature of most ecosystems, characterises the structure of habitat, and is considered an important driver of species distribution patterns. However, quantifying fine-scale heterogeneity of vegetation cover can be time consuming, and therefore it is seldom measured. Here, we determine if heterogeneity is worthwhile measuring, in addition to the amount of cover, when examining species distribution patterns. Further, we investigated the effect of the surrounding landscape heterogeneity on species occupancy. We tested the effect of cover and heterogeneity of trees and shrubs, and the context of the surrounding landscape (number of habitats and distance to an ecotone) on site occupancy of three mammal species (the black wallaby [Wallabia bicolor], the long-nosed bandicoot [Perameles nasuta], and the bush rat [Rattus fuscipes]) within a naturally heterogeneous landscape in a temperate region of Australia. We found that fine-scale heterogeneity of vegetation attributes is an important driver of mammal occurrence of two of these species. Further, we found that, although all three species responded positively to vegetation heterogeneity, different mammals vary in their response to different types of vegetation heterogeneity measurement. For example, the black wallaby responded to the proximity of an ecotone, and the bush rat and the long-nosed bandicoot responded to fine-scale heterogeneity of small tree cover, whereas none of the mammals responded to broad scale heterogeneity (i.e., the number of habitat types). Our results highlight the influence of methodological decisions, such as how heterogeneity vegetation is measured, in quantifying species responses to habitat structures. The findings confirm the importance of choosing meaningful heterogeneity measures when modelling the factors influencing occupancy of the species of interest. PMID:26394327

  7. Contrasting patterns of fine-scale herb layer species composition in temperate forests

    NASA Astrophysics Data System (ADS)

    Chudomelová, Markéta; Zelený, David; Li, Ching-Feng

    2017-04-01

    Although being well described at the landscape level, patterns in species composition of forest herb layer are rarely studied at smaller scales. Here, we examined fine-scale environmental determinants and spatial structures of herb layer communities in thermophilous oak- and hornbeam dominated forests of the south-eastern part of the Czech Republic. Species composition of herb layer vegetation and environmental variables were recorded within a fixed grid of 2 × 2 m subplots regularly distributed within 1-ha quadrate plots in three forest stands. For each site, environmental models best explaining species composition were constructed using constrained ordination analysis. Spatial eigenvector mapping was used to model and account for spatial structures in community variation. Mean Ellenberg indicator values calculated for each subplot were used for ecological interpretation of spatially structured residual variation. The amount of variation explained by environmental and spatial models as well as the selection of variables with the best explanatory power differed among sites. As an important environmental factor, relative elevation was common to all three sites, while pH and canopy openness were shared by two sites. Both environmental and community variation was mostly coarse-scaled, as was the spatially structured portion of residual variation. When corrected for bias due to spatial autocorrelation, those environmental factors with already weak explanatory power lost their significance. Only a weak evidence of possibly omitted environmental predictor was found for autocorrelated residuals of site models using mean Ellenberg indicator values. Community structure was determined by different factors at different sites. The relative importance of environmental filtering vs. spatial processes was also site specific, implying that results of fine-scale studies tend to be shaped by local conditions. Contrary to expectations based on other studies, overall dominance of

  8. Dispersal, mating events and fine-scale genetic structure in the lesser flat-headed bats.

    PubMed

    Hua, Panyu; Zhang, Libiao; Guo, Tingting; Flanders, Jon; Zhang, Shuyi

    2013-01-01

    Population genetic structure has important consequences in evolutionary processes and conservation genetics in animals. Fine-scale population genetic structure depends on the pattern of landscape, the permanent movement of individuals, and the dispersal of their genes during temporary mating events. The lesser flat-headed bat (Tylonycteris pachypus) is a nonmigratory Asian bat species that roosts in small groups within the internodes of bamboo stems and the habitats are fragmented. Our previous parentage analyses revealed considerable extra-group mating in this species. To assess the spatial limits and sex-biased nature of gene flow in the same population, we used 20 microsatellite loci and mtDNA sequencing of the ND2 gene to quantify genetic structure among 54 groups of adult flat-headed bats, at nine localities in South China. AMOVA and F(ST) estimates revealed significant genetic differentiation among localities. Alternatively, the pairwise F(ST) values among roosting groups appeared to be related to the incidence of associated extra-group breeding, suggesting the impact of mating events on fine-scale genetic structure. Global spatial autocorrelation analyses showed positive genetic correlation for up to 3 km, indicating the role of fragmented habitat and the specialized social organization as a barrier in the movement of individuals among bamboo forests. The male-biased dispersal pattern resulted in weaker spatial genetic structure between localities among males than among females, and fine-scale analyses supported that relatedness levels within internodes were higher among females than among males. Finally, only females were more related to their same sex roost mates than to individuals from neighbouring roosts, suggestive of natal philopatry in females.

  9. The Impact of Fine-Scale Disturbances on the Predictability of Vegetation Dynamics and Carbon Flux

    PubMed Central

    Hurtt, G. C.; Thomas, R. Q.; Fisk, J. P.; Dubayah, R. O.; Sheldon, S. L.

    2016-01-01

    Predictions from forest ecosystem models are limited in part by large uncertainties in the current state of the land surface, as previous disturbances have important and lasting influences on ecosystem structure and fluxes that can be difficult to detect. Likewise, future disturbances also present a challenge to prediction as their dynamics are episodic and complex and occur across a range of spatial and temporal scales. While large extreme events such as tropical cyclones, fires, or pest outbreaks can produce dramatic consequences, small fine-scale disturbance events are typically much more common and may be as or even more important. This study focuses on the impacts of these smaller disturbance events on the predictability of vegetation dynamics and carbon flux. Using data on vegetation structure collected for the same domain at two different times, i.e. “repeat lidar data”, we test high-resolution model predictions of vegetation dynamics and carbon flux across a range of spatial scales at an important tropical forest site at La Selva Biological Station, Costa Rica. We found that predicted height change from a height-structured ecosystem model compared well to lidar measured height change at the domain scale (~150 ha), but that the model-data mismatch increased exponentially as the spatial scale of evaluation decreased below 20 ha. We demonstrate that such scale-dependent errors can be attributed to errors predicting the pattern of fine-scale forest disturbances. The results of this study illustrate the strong impact fine-scale forest disturbances have on forest dynamics, ultimately limiting the spatial resolution of accurate model predictions. PMID:27093157

  10. Fine-Scale Habitat Heterogeneity Influences Occupancy in Terrestrial Mammals in a Temperate Region of Australia.

    PubMed

    Stirnemann, Ingrid; Mortelliti, Alessio; Gibbons, Philip; Lindenmayer, David B

    2015-01-01

    Vegetation heterogeneity is an inherent feature of most ecosystems, characterises the structure of habitat, and is considered an important driver of species distribution patterns. However, quantifying fine-scale heterogeneity of vegetation cover can be time consuming, and therefore it is seldom measured. Here, we determine if heterogeneity is worthwhile measuring, in addition to the amount of cover, when examining species distribution patterns. Further, we investigated the effect of the surrounding landscape heterogeneity on species occupancy. We tested the effect of cover and heterogeneity of trees and shrubs, and the context of the surrounding landscape (number of habitats and distance to an ecotone) on site occupancy of three mammal species (the black wallaby [Wallabia bicolor], the long-nosed bandicoot [Perameles nasuta], and the bush rat [Rattus fuscipes]) within a naturally heterogeneous landscape in a temperate region of Australia. We found that fine-scale heterogeneity of vegetation attributes is an important driver of mammal occurrence of two of these species. Further, we found that, although all three species responded positively to vegetation heterogeneity, different mammals vary in their response to different types of vegetation heterogeneity measurement. For example, the black wallaby responded to the proximity of an ecotone, and the bush rat and the long-nosed bandicoot responded to fine-scale heterogeneity of small tree cover, whereas none of the mammals responded to broad scale heterogeneity (i.e., the number of habitat types). Our results highlight the influence of methodological decisions, such as how heterogeneity vegetation is measured, in quantifying species responses to habitat structures. The findings confirm the importance of choosing meaningful heterogeneity measures when modelling the factors influencing occupancy of the species of interest.

  11. The Impact of Fine-Scale Disturbances on the Predictability of Vegetation Dynamics and Carbon Flux.

    PubMed

    Hurtt, G C; Thomas, R Q; Fisk, J P; Dubayah, R O; Sheldon, S L

    2016-01-01

    Predictions from forest ecosystem models are limited in part by large uncertainties in the current state of the land surface, as previous disturbances have important and lasting influences on ecosystem structure and fluxes that can be difficult to detect. Likewise, future disturbances also present a challenge to prediction as their dynamics are episodic and complex and occur across a range of spatial and temporal scales. While large extreme events such as tropical cyclones, fires, or pest outbreaks can produce dramatic consequences, small fine-scale disturbance events are typically much more common and may be as or even more important. This study focuses on the impacts of these smaller disturbance events on the predictability of vegetation dynamics and carbon flux. Using data on vegetation structure collected for the same domain at two different times, i.e. "repeat lidar data", we test high-resolution model predictions of vegetation dynamics and carbon flux across a range of spatial scales at an important tropical forest site at La Selva Biological Station, Costa Rica. We found that predicted height change from a height-structured ecosystem model compared well to lidar measured height change at the domain scale (~150 ha), but that the model-data mismatch increased exponentially as the spatial scale of evaluation decreased below 20 ha. We demonstrate that such scale-dependent errors can be attributed to errors predicting the pattern of fine-scale forest disturbances. The results of this study illustrate the strong impact fine-scale forest disturbances have on forest dynamics, ultimately limiting the spatial resolution of accurate model predictions.

  12. Dispersal, Mating Events and Fine-Scale Genetic Structure in the Lesser Flat-Headed Bats

    PubMed Central

    Guo, Tingting; Flanders, Jon; Zhang, Shuyi

    2013-01-01

    Population genetic structure has important consequences in evolutionary processes and conservation genetics in animals. Fine-scale population genetic structure depends on the pattern of landscape, the permanent movement of individuals, and the dispersal of their genes during temporary mating events. The lesser flat-headed bat (Tylonycteris pachypus) is a nonmigratory Asian bat species that roosts in small groups within the internodes of bamboo stems and the habitats are fragmented. Our previous parentage analyses revealed considerable extra-group mating in this species. To assess the spatial limits and sex-biased nature of gene flow in the same population, we used 20 microsatellite loci and mtDNA sequencing of the ND2 gene to quantify genetic structure among 54 groups of adult flat-headed bats, at nine localities in South China. AMOVA and FST estimates revealed significant genetic differentiation among localities. Alternatively, the pairwise FST values among roosting groups appeared to be related to the incidence of associated extra-group breeding, suggesting the impact of mating events on fine-scale genetic structure. Global spatial autocorrelation analyses showed positive genetic correlation for up to 3 km, indicating the role of fragmented habitat and the specialized social organization as a barrier in the movement of individuals among bamboo forests. The male-biased dispersal pattern resulted in weaker spatial genetic structure between localities among males than among females, and fine-scale analyses supported that relatedness levels within internodes were higher among females than among males. Finally, only females were more related to their same sex roost mates than to individuals from neighbouring roosts, suggestive of natal philopatry in females. PMID:23349888

  13. Direct and indirect genetic and fine-scale location effects on breeding date in song sparrows.

    PubMed

    Germain, Ryan R; Wolak, Matthew E; Arcese, Peter; Losdat, Sylvain; Reid, Jane M

    2016-11-01

    Quantifying direct and indirect genetic effects of interacting females and males on variation in jointly expressed life-history traits is central to predicting microevolutionary dynamics. However, accurately estimating sex-specific additive genetic variances in such traits remains difficult in wild populations, especially if related individuals inhabit similar fine-scale environments. Breeding date is a key life-history trait that responds to environmental phenology and mediates individual and population responses to environmental change. However, no studies have estimated female (direct) and male (indirect) additive genetic and inbreeding effects on breeding date, and estimated the cross-sex genetic correlation, while simultaneously accounting for fine-scale environmental effects of breeding locations, impeding prediction of microevolutionary dynamics. We fitted animal models to 38 years of song sparrow (Melospiza melodia) phenology and pedigree data to estimate sex-specific additive genetic variances in breeding date, and the cross-sex genetic correlation, thereby estimating the total additive genetic variance while simultaneously estimating sex-specific inbreeding depression. We further fitted three forms of spatial animal model to explicitly estimate variance in breeding date attributable to breeding location, overlap among breeding locations and spatial autocorrelation. We thereby quantified fine-scale location variances in breeding date and quantified the degree to which estimating such variances affected the estimated additive genetic variances. The non-spatial animal model estimated nonzero female and male additive genetic variances in breeding date (sex-specific heritabilities: 0·07 and 0·02, respectively) and a strong, positive cross-sex genetic correlation (0·99), creating substantial total additive genetic variance (0·18). Breeding date varied with female, but not male inbreeding coefficient, revealing direct, but not indirect, inbreeding

  14. Influences of fluidic interfaces during formation of fine-scale composites by chaotic mixing of melts

    SciTech Connect

    Zhang, D.F.; Zumbrunnen, D.A.

    1995-12-31

    Two-dimensional chaotic mixing of Newtonian fluids with active interfaces was investigated numerically to disclose influences on the formation of fine-scale structures in melts which may be captured by solidification to yield composites. Mixing of two immiscible fluids was confined to a rectangular cavity with periodically driven upper and lower surfaces. Interfacial forces and the interactions via the interface with the transient flow fields in each phase were considered. The evolving morphologies of active interfaces and interactions with flow fields in both the minor and major phases were disclosed for different interfacial tensions and phase viscosity ratios.

  15. Modelling Soil-Landscapes in Coastal California Hills Using Fine Scale Terrestrial Lidar

    NASA Astrophysics Data System (ADS)

    Prentice, S.; Bookhagen, B.; Kyriakidis, P. C.; Chadwick, O.

    2013-12-01

    Digital elevation models (DEMs) are the dominant input to spatially explicit digital soil mapping (DSM) efforts due to their increasing availability and the tight coupling between topography and soil variability. Accurate characterization of this coupling is dependent on DEM spatial resolution and soil sampling density, both of which may limit analyses. For example, DEM resolution may be too coarse to accurately reflect scale-dependent soil properties yet downscaling introduces artifactual uncertainty unrelated to deterministic or stochastic soil processes. We tackle these limitations through a DSM effort that couples moderately high density soil sampling with a very fine scale terrestrial lidar dataset (20 cm) implemented in a semiarid rolling hillslope domain where terrain variables change rapidly but smoothly over short distances. Our guiding hypothesis is that in this diffusion-dominated landscape, soil thickness is readily predicted by continuous terrain attributes coupled with catenary hillslope segmentation. We choose soil thickness as our keystone dependent variable for its geomorphic and hydrologic significance, and its tendency to be a primary input to synthetic ecosystem models. In defining catenary hillslope position we adapt a logical rule-set approach that parses common terrain derivatives of curvature and specific catchment area into discrete landform elements (LE). Variograms and curvature-area plots are used to distill domain-scale terrain thresholds from short range order noise characteristic of very fine-scale spatial data. The revealed spatial thresholds are used to condition LE rule-set inputs, rendering a catenary LE map that leverages the robustness of fine-scale terrain data to create a generalized interpretation of soil geomorphic domains. Preliminary regressions show that continuous terrain variables alone (curvature, specific catchment area) only partially explain soil thickness, and only in a subset of soils. For example, at spatial

  16. Patterns of fine-scale plant species richness in dry grasslands across the eastern Balkan Peninsula

    NASA Astrophysics Data System (ADS)

    Palpurina, Salza; Chytrý, Milan; Tzonev, Rossen; Danihelka, Jiří; Axmanová, Irena; Merunková, Kristina; Duchoň, Mário; Karakiev, Todor

    2015-02-01

    Fine-scale plant species richness varies across habitats, climatic and biogeographic regions, but the large-scale context of this variation is insufficiently explored. The patterns at the borders between biomes harbouring rich but different floras are of special interest. Dry grasslands of the eastern Balkan Peninsula, situated in the Eurasian forest-steppe zone and developed under Mediterranean influence, are a specific case of such biome transition. However, there are no studies assessing the patterns of fine-scale species richness and their underlying factors across the eastern Balkans. To explore these patterns, we sampled dry and semi-dry grasslands (phytosociological class Festuco-Brometea) across Bulgaria and SE Romania. In total, 172 vegetation plots of 10 × 10 m2 were sampled, in which all vascular plant species were recorded, soil depth was measured, and soil samples were collected and analysed in a laboratory for pH and plant-available nutrients. Geographic coordinates were used to extract selected climatic variables. Regression trees and linear regressions were used to quantify the relationships between species richness and environmental variables. Climatic factors were identified as the main drivers of species richness: (1) Species richness was strongly positively correlated with the mean temperature of the coldest month: sub-Mediterranean areas of S and E Bulgaria, characterized by warmer winters, were more species-rich. (2) Outside the sub-Mediterranean areas, species richness strongly increased with annual precipitation, which was primarily controlled by altitude. (3) Bedrock type and soil pH also significantly affected dry grassland richness outside the sub-Mediterranean areas. These results suggest that fine-scale species richness of dry grasslands over large areas is driven by processes at the regional level, especially by the difference in the species pools of large regions, in our case the Continental and Mediterranean biogeographic regions

  17. Magnetic Signatures of Fine-scale Processes in the Ocean Surface Layer

    NASA Astrophysics Data System (ADS)

    Soloviev, A.; Dean, C.; Avera, W. E.

    2015-12-01

    Fine-scale processes in the upper ocean turbulent boundary layer may have a measurable electromagnetic signature. In order to study magnetic signatures of these fine-scale processes, we have applied a magnetohydrodynamic (MHD) model combining a 3D computational fluid dynamics model and electromagnetic block, based on ANSYS Fluent software. In addition, the hydrodynamic component of the MHD model is coupled with a radar imaging algorithm, which potentially provides a link to synthetic aperture radar (SAR) satellite imagery. Capabilities of this model have been demonstrated using a simulation and observation of an internal wave soliton in the Straits of Florida, observed with in situ instrumentation (ADCP mooring) and COSMO Sky Med (SAR) satellite image. We have applied this model to study magnetic signatures of surface waves, freshwater lenses, spatially coherent organized motions in the near-surface layer of the ocean (Langmuir circulation and ramp-like structures), and bio-turbulence induced by diel vertical migrations of zooplankton in some areas of the ocean. Investigation of electromagnetic signatures in upper ocean processes offers a valuable new prospect in air-sea interaction.

  18. Fine-Scale Spatial Heterogeneity in the Distribution of Waterborne Protozoa in a Drinking Water Reservoir

    PubMed Central

    Burnet, Jean-Baptiste; Ogorzaly, Leslie; Penny, Christian; Cauchie, Henry-Michel

    2015-01-01

    Background: The occurrence of faecal pathogens in drinking water resources constitutes a threat to the supply of safe drinking water, even in industrialized nations. To efficiently assess and monitor the risk posed by these pathogens, sampling deserves careful design, based on preliminary knowledge on their distribution dynamics in water. For the protozoan pathogens Cryptosporidium and Giardia, only little is known about their spatial distribution within drinking water supplies, especially at fine scale. Methods: Two-dimensional distribution maps were generated by sampling cross-sections at meter resolution in two different zones of a drinking water reservoir. Samples were analysed for protozoan pathogens as well as for E. coli, turbidity and physico-chemical parameters. Results: Parasites displayed heterogeneous distribution patterns, as reflected by significant (oo)cyst density gradients along reservoir depth. Spatial correlations between parasites and E. coli were observed near the reservoir inlet but were absent in the downstream lacustrine zone. Measurements of surface and subsurface flow velocities suggest a role of local hydrodynamics on these spatial patterns. Conclusion: This fine-scale spatial study emphasizes the importance of sampling design (site, depth and position on the reservoir) for the acquisition of representative parasite data and for optimization of microbial risk assessment and monitoring. Such spatial information should prove useful to the modelling of pathogen transport dynamics in drinking water supplies. PMID:26404350

  19. Fine-scale estimations of bioclimatic change in the Valencia region, Spain

    NASA Astrophysics Data System (ADS)

    Miró, Juan Javier; Estrela, María José; Caselles, Vicente; Olcina-Cantos, Jorge

    2016-11-01

    Recent advances in statistical downscaling have allowed the reconstruction of temperatures for the complete 1948-2011 period in a spatial resolution of 90 m and without gaps for the Valencian Community (Spain) and bordering areas. It presently enables analyses in this region, which allows the determination of recent temperature changes at subregional and local scales. The present work focuses on obtaining the thermicity index according to Rivas-Martínez, a well-known indicator of different thermotypes associated with bioclimatic horizons. The change in this index, which has happened in the region between 1948 and 2011, was calculated by generating fine-scale maps of the potential extension of different thermotypes. The results show a greater regression for the thermotypes in a finicolous position, e.g. Orotemperate, Supratemperate and Supramediterranean horizons, which herein indicate greater potential vulnerability in climate change. In the absence of, and given the need for, such fine-scale information, this work should be useful for specialized researchers to spatially limit the potentially most vulnerable biotopes to climate change.

  20. Theory and data for simulating fine-scale human movement in an urban environment

    PubMed Central

    Perkins, T. Alex; Garcia, Andres J.; Paz-Soldán, Valerie A.; Stoddard, Steven T.; Reiner, Robert C.; Vazquez-Prokopec, Gonzalo; Bisanzio, Donal; Morrison, Amy C.; Halsey, Eric S.; Kochel, Tadeusz J.; Smith, David L.; Kitron, Uriel; Scott, Thomas W.; Tatem, Andrew J.

    2014-01-01

    Individual-based models of infectious disease transmission depend on accurate quantification of fine-scale patterns of human movement. Existing models of movement either pertain to overly coarse scales, simulate some aspects of movement but not others, or were designed specifically for populations in developed countries. Here, we propose a generalizable framework for simulating the locations that an individual visits, time allocation across those locations, and population-level variation therein. As a case study, we fit alternative models for each of five aspects of movement (number, distance from home and types of locations visited; frequency and duration of visits) to interview data from 157 residents of the city of Iquitos, Peru. Comparison of alternative models showed that location type and distance from home were significant determinants of the locations that individuals visited and how much time they spent there. We also found that for most locations, residents of two neighbourhoods displayed indistinguishable preferences for visiting locations at various distances, despite differing distributions of locations around those neighbourhoods. Finally, simulated patterns of time allocation matched the interview data in a number of ways, suggesting that our framework constitutes a sound basis for simulating fine-scale movement and for investigating factors that influence it. PMID:25142528

  1. Fine-Scale Crossover Rate Variation on the Caenorhabditis elegans X Chromosome

    PubMed Central

    Bernstein, Max R.; Rockman, Matthew V.

    2016-01-01

    Meiotic recombination creates genotypic diversity within species. Recombination rates vary substantially across taxa, and the distribution of crossovers can differ significantly among populations and between sexes. Crossover locations within species have been found to vary by chromosome and by position within chromosomes, where most crossover events occur in small regions known as recombination hotspots. However, several species appear to lack hotspots despite significant crossover heterogeneity. The nematode Caenorhabditis elegans was previously found to have the least fine-scale variation in crossover distribution among organisms studied to date. It is unclear whether this pattern extends to the X chromosome given its unique compaction through the pachytene stage of meiotic prophase in hermaphrodites. We generated 798 recombinant nested near-isogenic lines (NILs) with crossovers in a 1.41 Mb region on the left arm of the X chromosome to determine if its recombination landscape is similar to that of the autosomes. We find that the fine-scale variation in crossover rate is lower than that of other model species, and is inconsistent with hotspots. The relationship of genomic features to crossover rate is dependent on scale, with GC content, histone modifications, and nucleosome occupancy being negatively associated with crossovers. We also find that the abundances of 4- to 6-bp DNA motifs significantly explain crossover density. These results are consistent with recombination occurring at unevenly distributed sites of open chromatin. PMID:27172189

  2. Fine-Scale Population Structure of Blue Whale Wintering Aggregations in the Gulf of California

    PubMed Central

    Costa-Urrutia, Paula; Sanvito, Simona; Victoria-Cota, Nelva; Enríquez-Paredes, Luis; Gendron, Diane

    2013-01-01

    Population differentiation in environments without well-defined geographical barriers represents a challenge for wildlife management. Based on a comprehensive database of individual sighting records (1988–2009) of blue whales from the winter/calving Gulf of California, we assessed the fine-scale genetic and spatial structure of the population using individual-based approaches. Skin samples of 187 individuals were analyzed for nine microsatellite loci. A single population with no divergence among years and months and no isolation by distance (Rxy = 0.1–0.001, p>0.05) were found. We ran two Bayesian clustering methods using Structure and Geneland softwares in two different ways: 1) a general analysis including all individuals in which a single cluster was identified with both softwares; 2) a specific analysis of females only in which two main clusters (Loreto Bay and northern areas, and San Jose-La Paz Bay area) were revealed by Geneland program. This study provides information indicating that blue whales wintering in the Gulf of California are part of a single population unit and showed a fine-scale structure among females, possibly associated with their high site fidelity, particularly when attending calves. It is likely that the loss of genetic variation is minimized by male mediated gene flow, which may reduce the genetic drift effect. Opportunities for kin selection may also influence calf survival and, in consequence, have a positive impact on population demography in this small and endangered population. PMID:23505485

  3. Fine-scale genetic structure in populations of the Chagas' disease vector Triatoma infestans (Hemiptera, Reduvidae).

    PubMed

    Pérez de Rosas, Alicia R; Segura, Elsa L; Fusco, Octavio; Guiñazú, Adolfo L Bareiro; García, Beatriz A

    2013-03-01

    Fine scale patterns of genetic structure and dispersal in Triatoma infestans populations from Argentina was analysed. A total of 314 insects from 22 domestic and peridomestic sites from the locality of San Martín (Capayán department, Catamarca province) were typed for 10 polymorphic microsatellite loci. The results confirm subdivision of T. infestans populations with restricted dispersal among sampling sites and suggest inbreeding and/or stratification within the different domestic and peridomestic structures. Spatial correlation analysis showed that the scale of structuring is approximately of 400 m, indicating that active dispersal would occur within this distance range. It was detected difference in scale of structuring among sexes, with females dispersing over greater distances than males. This study suggests that insecticide treatment and surveillance should be extended within a radius of 400 m around the infested area, which would help to reduce the probability of reinfestation by covering an area of active dispersal. The inferences made from fine-scale spatial genetic structure analyses of T. infestans populations has demonstrated to be important for community-wide control programs, providing a complementary approach to help improve vector control strategies.

  4. Two-Locus Likelihoods Under Variable Population Size and Fine-Scale Recombination Rate Estimation

    PubMed Central

    Kamm, John A.; Spence, Jeffrey P.; Chan, Jeffrey; Song, Yun S.

    2016-01-01

    Two-locus sampling probabilities have played a central role in devising an efficient composite-likelihood method for estimating fine-scale recombination rates. Due to mathematical and computational challenges, these sampling probabilities are typically computed under the unrealistic assumption of a constant population size, and simulation studies have shown that resulting recombination rate estimates can be severely biased in certain cases of historical population size changes. To alleviate this problem, we develop here new methods to compute the sampling probability for variable population size functions that are piecewise constant. Our main theoretical result, implemented in a new software package called LDpop, is a novel formula for the sampling probability that can be evaluated by numerically exponentiating a large but sparse matrix. This formula can handle moderate sample sizes (n≤50) and demographic size histories with a large number of epochs (D≥64). In addition, LDpop implements an approximate formula for the sampling probability that is reasonably accurate and scales to hundreds in sample size (n≥256). Finally, LDpop includes an importance sampler for the posterior distribution of two-locus genealogies, based on a new result for the optimal proposal distribution in the variable-size setting. Using our methods, we study how a sharp population bottleneck followed by rapid growth affects the correlation between partially linked sites. Then, through an extensive simulation study, we show that accounting for population size changes under such a demographic model leads to substantial improvements in fine-scale recombination rate estimation. PMID:27182948

  5. Fine-scale population structure of blue whale wintering aggregations in the Gulf of California.

    PubMed

    Costa-Urrutia, Paula; Sanvito, Simona; Victoria-Cota, Nelva; Enríquez-Paredes, Luis; Gendron, Diane

    2013-01-01

    Population differentiation in environments without well-defined geographical barriers represents a challenge for wildlife management. Based on a comprehensive database of individual sighting records (1988-2009) of blue whales from the winter/calving Gulf of California, we assessed the fine-scale genetic and spatial structure of the population using individual-based approaches. Skin samples of 187 individuals were analyzed for nine microsatellite loci. A single population with no divergence among years and months and no isolation by distance (Rxy = 0.1-0.001, p>0.05) were found. We ran two bayesian clustering methods using Structure and Geneland softwares in two different ways: 1) a general analysis including all individuals in which a single cluster was identified with both softwares; 2) a specific analysis of females only in which two main clusters (Loreto Bay and northern areas, and San Jose-La Paz Bay area) were revealed by Geneland program. This study provides information indicating that blue whales wintering in the Gulf of California are part of a single population unit and showed a fine-scale structure among females, possibly associated with their high site fidelity, particularly when attending calves. It is likely that the loss of genetic variation is minimized by male mediated gene flow, which may reduce the genetic drift effect. Opportunities for kin selection may also influence calf survival and, in consequence, have a positive impact on population demography in this small and endangered population.

  6. Fine-Scale Spatial Heterogeneity in the Distribution of Waterborne Protozoa in a Drinking Water Reservoir.

    PubMed

    Burnet, Jean-Baptiste; Ogorzaly, Leslie; Penny, Christian; Cauchie, Henry-Michel

    2015-09-23

    The occurrence of faecal pathogens in drinking water resources constitutes a threat to the supply of safe drinking water, even in industrialized nations. To efficiently assess and monitor the risk posed by these pathogens, sampling deserves careful design, based on preliminary knowledge on their distribution dynamics in water. For the protozoan pathogens Cryptosporidium and Giardia, only little is known about their spatial distribution within drinking water supplies, especially at fine scale. Two-dimensional distribution maps were generated by sampling cross-sections at meter resolution in two different zones of a drinking water reservoir. Samples were analysed for protozoan pathogens as well as for E. coli, turbidity and physico-chemical parameters. Parasites displayed heterogeneous distribution patterns, as reflected by significant (oo)cyst density gradients along reservoir depth. Spatial correlations between parasites and E. coli were observed near the reservoir inlet but were absent in the downstream lacustrine zone. Measurements of surface and subsurface flow velocities suggest a role of local hydrodynamics on these spatial patterns. This fine-scale spatial study emphasizes the importance of sampling design (site, depth and position on the reservoir) for the acquisition of representative parasite data and for optimization of microbial risk assessment and monitoring. Such spatial information should prove useful to the modelling of pathogen transport dynamics in drinking water supplies.

  7. Networks Depicting the Fine-Scale Co-Occurrences of Fungi in Soil Horizons

    PubMed Central

    Toju, Hirokazu; Kishida, Osamu; Katayama, Noboru; Takagi, Kentaro

    2016-01-01

    Fungi in soil play pivotal roles in nutrient cycling, pest controls, and plant community succession in terrestrial ecosystems. Despite the ecosystem functions provided by soil fungi, our knowledge of the assembly processes of belowground fungi has been limited. In particular, we still have limited knowledge of how diverse functional groups of fungi interact with each other in facilitative and competitive ways in soil. Based on the high-throughput sequencing data of fungi in a cool-temperate forest in northern Japan, we analyzed how taxonomically and functionally diverse fungi showed correlated fine-scale distributions in soil. By uncovering pairs of fungi that frequently co-occurred in the same soil samples, networks depicting fine-scale co-occurrences of fungi were inferred at the O (organic matter) and A (surface soil) horizons. The results then led to the working hypothesis that mycorrhizal, endophytic, saprotrophic, and pathogenic fungi could form compartmentalized (modular) networks of facilitative, antagonistic, and/or competitive interactions in belowground ecosystems. Overall, this study provides a research basis for further understanding how interspecific interactions, along with sharing of niches among fungi, drive the dynamics of poorly explored biospheres in soil. PMID:27861486

  8. Fine-Scale Structure of the Moho From Receiver Functions: Effects of a Deforming Crust

    NASA Astrophysics Data System (ADS)

    Zandt, G.; Gilbert, H.; Ozacar, A.; Owens, T. J.

    2004-12-01

    Andrija Mohorovicic, a Croatian seismologist, is credited with the first estimation in 1906 of crustal thickness using the critically refracted phase Pn. The crust-mantle boundary has become commonly known as the Moho and its depth, structure, formation, and evolution remains an important research topic in seismology, petrology, and tectonics. Other seismic phases sensitive to Moho depth and structure are the converted phases Ps and Sp, and the associated 2p1s and 1p2s reverberation phases that are isolated in receiver function waveforms. With sufficient station coverage, multiple receiver functions can be migrated and stacked into cross-sections of the crust. Crustal cross-sections from tectonically active regions reveal dramatic variations in amplitude and frequency content of Moho phases that we associate with fine-scale structure, and possibly anisotropy at the crust-mantle boundary. The Moho amplitude or "brightness" is a measure of the crust-mantle impedance contrast, thickness and structure within the crust-mantle boundary, and effects of scattering from 3D structure. Processes directly related to these Moho structures include crustal thickening, crustal extension, crustal flow, delamination or convective removal, and eclogitization. Therefore, the fine-scale seismological structure of the Moho is an important constraint in regional tectonic reconstructions. Examples of receiver function crustal images and their tectonic implications from the western US, South American Andes, and the Tibetan plateau will be reviewed.

  9. Fine-Scale Genetic Structure and Reproductive Biology of the Blueberry Pathogen Monilinia vaccinii-corymbosi.

    PubMed

    Burchhardt, Kathleen M; Miller, Megan E; Cline, William O; Cubeta, Marc A

    2017-02-01

    The fungus Monilinia vaccinii-corymbosi, a pathogen of Vaccinium spp., requires asexual and sexual spore production to complete its life cycle. A recent study found population structuring of M. vaccinii-corymbosi over a broad spatial scale in the United States. In this study, we examined fine-scale genetic structuring, temporal dynamics, and reproductive biology within a 125-by-132-m blueberry plot from 2010 to 2012. In total, 395 isolates of M. vaccinii-corymbosi were sampled from infected shoots and fruit to examine their multilocus haplotype (MLH) using microsatellite markers. The MLH of 190 single-ascospore isolates from 21 apothecia was also determined. Little to no genetic differentiation and unrestricted gene flow were detected among four sampled time points and between infected tissue types. Discriminant analysis of principal components suggested genetic structuring within the field, with at least K = 3 genetically distinct clusters maintained over four sampled time points. Single-ascospore progeny from eight apothecia had identical MLH and at least two distinct MLH were detected from 13 apothecia. Tests for linkage disequilibrium suggested that genetically diverse ascospore progeny were the product of recombination. This study supports the idea that the fine-scale dynamics of M. vaccinii-corymbosi may be complex, with genetic structuring, inbreeding, and outcrossing detected in the study area.

  10. Nonlinear dendritic integration of electrical and chemical synaptic inputs drives fine-scale correlations

    PubMed Central

    Trenholm, Stuart; McLaughlin, Amanda J; Schwab, David J; Turner, Maxwell H; Smith, Robert G; Rieke, Fred; Awatramani, Gautam B

    2014-01-01

    Throughout the CNS, gap junction–mediated electrical signals synchronize neural activity on millisecond timescales via cooperative interactions with chemical synapses. However, gap junction–mediated synchrony has rarely been studied in the context of varying spatiotemporal patterns of electrical and chemical synaptic activity. Thus, the mechanism underlying fine-scale synchrony and its relationship to neural coding remain unclear. We examined spike synchrony in pairs of genetically identified, electrically coupled ganglion cells in mouse retina. We found that coincident electrical and chemical synaptic inputs, but not electrical inputs alone, elicited synchronized dendritic spikes in subregions of coupled dendritic trees. The resulting nonlinear integration produced fine-scale synchrony in the cells’ spike output, specifically for light stimuli driving input to the regions of dendritic overlap. In addition, the strength of synchrony varied inversely with spike rate. Together, these features may allow synchronized activity to encode information about the spatial distribution of light that is ambiguous on the basis of spike rate alone. PMID:25344631

  11. Networks Depicting the Fine-Scale Co-Occurrences of Fungi in Soil Horizons.

    PubMed

    Toju, Hirokazu; Kishida, Osamu; Katayama, Noboru; Takagi, Kentaro

    2016-01-01

    Fungi in soil play pivotal roles in nutrient cycling, pest controls, and plant community succession in terrestrial ecosystems. Despite the ecosystem functions provided by soil fungi, our knowledge of the assembly processes of belowground fungi has been limited. In particular, we still have limited knowledge of how diverse functional groups of fungi interact with each other in facilitative and competitive ways in soil. Based on the high-throughput sequencing data of fungi in a cool-temperate forest in northern Japan, we analyzed how taxonomically and functionally diverse fungi showed correlated fine-scale distributions in soil. By uncovering pairs of fungi that frequently co-occurred in the same soil samples, networks depicting fine-scale co-occurrences of fungi were inferred at the O (organic matter) and A (surface soil) horizons. The results then led to the working hypothesis that mycorrhizal, endophytic, saprotrophic, and pathogenic fungi could form compartmentalized (modular) networks of facilitative, antagonistic, and/or competitive interactions in belowground ecosystems. Overall, this study provides a research basis for further understanding how interspecific interactions, along with sharing of niches among fungi, drive the dynamics of poorly explored biospheres in soil.

  12. Differential oscillatory encoding of foreign speech.

    PubMed

    Pérez, Alejandro; Carreiras, Manuel; Gillon Dowens, Margaret; Duñabeitia, Jon Andoni

    2015-08-01

    Neuronal oscillations play a key role in auditory perception of verbal input, with the oscillatory rhythms of the brain showing synchronization with specific frequencies of speech. Here we investigated the neural oscillatory patterns associated with perceiving native, foreign, and unknown speech. Spectral power and phase synchronization were compared to those of a silent context. Power synchronization to native speech was found in frequency ranges corresponding to the theta band, while no synchronization patterns were found for the foreign speech context and the unknown language context. For phase synchrony, the native and unknown languages showed higher synchronization in the theta-band than the foreign language when compared to the silent condition. These results suggest that neural synchronization patterns are markedly different for native and foreign languages.

  13. Effects of Fine-Scale Landscape Variability on Satellite-Derived Land Surface Temperature Products Over Sparse Vegetation Canopies

    NASA Astrophysics Data System (ADS)

    Powell, R. L.; Goulden, M.; Peterson, S.; Roberts, D. A.; Still, C. J.

    2015-12-01

    Temperature is a primary environmental control on biological systems and processes at a range of spatial and temporal scales, from controlling biochemical processes such as photosynthesis to influencing continental-scale species distribution. The Landsat satellite series provides a long record (since the mid-1980s) of relatively high spatial resolution thermal infrared (TIR) imagery, from which we derive land surface temperature (LST) grids. Here, we investigate fine spatial resolution factors that influence Landsat-derived LST over a spectrally and spatially heterogeneous landscape. We focus on paired sites (inside/outside a 1994 fire scar) within a pinyon-juniper scrubland in Southern California. The sites have nearly identical micro-meteorology and vegetation species composition, but distinctly different vegetation abundance and structure. The tower at the unburned site includes a number of in-situ imaging tools to quantify vegetation properties, including a thermal camera on a pan-tilt mount, allowing hourly characterization of landscape component temperatures (e.g., sunlit canopy, bare soil, leaf litter). We use these in-situ measurements to assess the impact of fine-scale landscape heterogeneity on estimates of LST, including sensitivity to (i) the relative abundance of component materials, (ii) directional effects due to solar and viewing geometry, (iii) duration of sunlit exposure for each compositional type, and (iv) air temperature. To scale these properties to Landsat spatial resolution (~100-m), we characterize the sub-pixel composition of landscape components (in addition to shade) by applying spectral mixture analysis (SMA) to the Landsat Operational Land Imager (OLI) spectral bands and test the sensitivity of the relationships established with the in-situ data at this coarser scale. The effects of vegetation abundance and cover height versus other controls on satellite-derived estimates of LST will be assessed by comparing estimates at the burned vs

  14. Strontium isotopes delineate fine-scale natal origins and migration histories of Pacific salmon

    PubMed Central

    Brennan, Sean R.; Zimmerman, Christian E.; Fernandez, Diego P.; Cerling, Thure E.; McPhee, Megan V.; Wooller, Matthew J.

    2015-01-01

    Highly migratory organisms present major challenges to conservation efforts. This is especially true for exploited anadromous fish species, which exhibit long-range dispersals from natal sites, complex population structures, and extensive mixing of distinct populations during exploitation. By tracing the migratory histories of individual Chinook salmon caught in fisheries using strontium isotopes, we determined the relative production of natal habitats at fine spatial scales and different life histories. Although strontium isotopes have been widely used in provenance research, we present a new robust framework to simultaneously assess natal sources and migrations of individuals within fishery harvests through time. Our results pave the way for investigating how fine-scale habitat production and life histories of salmon respond to perturbations—providing crucial insights for conservation. PMID:26601173

  15. Ecological segregation drives fine-scale cytotype distribution of Senecio carniolicus in the Eastern Alps

    PubMed Central

    Hülber, Karl; Sonnleitner, Michaela; Flatscher, Ruth; Berger, Andreas; Dobrovsky, Rainer; Niessner, Sophie; Nigl, Thomas; Schneeweiss, Gerald M.; Kubešová, Magdalena; Rauchová, Jana; Suda, Jan; Schönswetter, Peter

    2011-01-01

    In order to uncover patterns and processes of segregation of co-existing cytotypes, we investigated a zone in the eastern Alps (Austria) where diploid and hexaploid individuals of the alpine herb Senecio carniolicus Willd. (Asteraceae) co-occur. Linking the fine-scale distribution of cytotypes to environmental and spatial factors revealed segregation along an ecological gradient, which was also reflected in the cytotype-associated plant assemblages. Compared to diploids, hexaploids are found in more species-rich and denser communities. This may be due to their better competitive ability and lower tolerance of abiotic stress compared to the diploids. The lack of any intermediate cytotypes suggests the presence of strong reproductive isolation mechanisms, whose nature is, however, elusive. PMID:22318659

  16. Strontium isotopes delineate fine-scale natal origins and migration histories of Pacific salmon

    USGS Publications Warehouse

    Brennan, Sean R.; Zimmerman, Christian E.; Fernandez, Diego P.; Cerling, Thure E.; McPhee, Megan V.; Wooller, Matthew J.

    2015-01-01

    Highly migratory organisms present major challenges to conservation efforts. This is especially true for exploited anadromous fish species, which exhibit long-range dispersals from natal sites, complex population structures, and extensive mixing of distinct populations during exploitation. By tracing the migratory histories of individual Chinook salmon caught in fisheries using strontium isotopes, we determined the relative production of natal habitats at fine spatial scales and different life histories. Although strontium isotopes have been widely used in provenance research, we present a new robust framework to simultaneously assess natal sources and migrations of individuals within fishery harvests through time. Our results pave the way for investigating how fine-scale habitat production and life histories of salmon respond to perturbations—providing crucial insights for conservation.

  17. Fine-scale thermohaline structure revealed by seismic reflection profiling in the Gulf of California.

    NASA Astrophysics Data System (ADS)

    Paramo, P.; Holbrook, W. S.; Pearse, S.; Schmitt, R. W.

    2003-12-01

    We present cross-sectional acoustic images of the ocean revealed by standard seismic-reflection profiling acquired in the Gulf of California. The data were acquired with a 6 km streamer, 480 channels and 20 gun array with a frequency content of 10-120 Hz. Seismic lines acquired in several different locations throughout the Gulf of California show similar characteristics. The images reveal acoustic reflections caused by fine-scale thermohaline structure. These reflections are prominent in the uppermost 500 m of the water column and become weaker with depth until they reach 1000 m, where they disappear as the abyssal waters become acoustically transparent. Time-lapse cross-sectional images show no overall change in reflectance characteristics in the uppermost 500m and in deeper waters, but the location of the reflections varies slightly between the images. We believe that these changes in location are consistent with the dynamics of internal waves.

  18. Pressure spectra for vortex models of fine-scale homogeneous turbulence

    NASA Astrophysics Data System (ADS)

    Pullin, D. I.

    1995-04-01

    Pressure spectra at large wave numbers are calculated for Lundgren-Townsend vortex models of the fine scales of homogeneous turbulence. Specific results are given for the Burgers vortex and also for the Lundgren-strained spiral vortex. For the latter case, it is found that the contribution to the shell-summed spectrum produced by the interaction between the axisymmetric and nonaxisymmetric components of the velocity field is proportional to k-7/3 (k=‖k‖ is the modulus of the wave number) in agreement with Kolmogorov-type dimensional arguments. Numerical estimates of the dimensionless prefactors for this component are obtained in Kolmogorov scaling variables and comparisons are made with results from the Batchelor-Kolmogorov theory, and with experimental measurement.

  19. MHD Wave Modes Resolved in Fine-Scale Chromospheric Magnetic Structures

    NASA Astrophysics Data System (ADS)

    Verth, G.; Jess, D. B.

    2016-02-01

    Due to its complex and dynamic fine-scale structure, the chromosphere is a particularly challenging region of the Sun's atmosphere to understand. It is now widely accepted that to model chromospheric dynamics, even on a magnetohydrodynamic (MHD) scale, while also calculating spectral line emission, one must realistically include the effects of partial ionization and radiative transfer in a multi-fluid plasma under non-LTE conditions. Accurate quantification of MHD wave energetics must be founded on a precise identification of the actual wave mode being observed. This chapter focuses on MHD kink-mode identification, MHD sausage mode identification, and MHD torsional Alfvén wave identification. It then reviews progress in determining more accurate energy flux estimations of specific MHD wave modes observed in the chromosphere. The chapter finally examines how the discovery of these MHD wave modes has helped us advance the field of chromospheric magnetoseismology.

  20. Fine-scale detection of pollutants by a benthic marine jellyfish.

    PubMed

    Epstein, Hannah E; Templeman, Michelle A; Kingsford, Michael J

    2016-06-15

    Local sources of pollution can vary immensely on small geographic scales and short time frames due to differences in runoff and adjacent land use. This study examined the rate of uptake and retention of trace metals in Cassiopea maremetens, a benthic marine jellyfish, over a short time frame and in the presence of multiple pollutants. This study also validated the ability of C. maremetens to uptake metals in the field. Experimental manipulation demonstrated that metal accumulation in jellyfish tissue began within 24h of exposure to treated water and trended for higher accumulation in the presence of multiple pollutants. C. maremetens was found to uptake trace metals in the field and provide unique signatures among locations. This fine-scale detection and rapid accumulation of metals in jellyfish tissue can have major implications for both biomonitoring and the trophic transfer of pollutants through local ecosystems. Copyright © 2016 Elsevier Ltd. All rights reserved.

  1. Methods Linking Predictive Weather and Fine-scale Soil Moisture to Crop and Irrigation Decision Tools

    NASA Astrophysics Data System (ADS)

    Jones, A. S.; Andales, A.; Niemann, J. D.; Cammarere, M.; Fletcher, S. J.; Corbett, J.

    2016-12-01

    More than 30% of all irrigated US agricultural output comes from the lands sustained by the Ogallala Aquifer in the western Great Plains. The agricultural production practices in six states (CO, KS, NE, NM, OK, and TX) affect water usage and the interactive multi-scale phytobiome processes of the individual crop types. Tested methods to optimize water use and crop production at the field-scale are needed as the Ogallala water resources undergo change. This work presents methods used to link predictive weather and downscaled soil moisture at 10-30 m scales for use in crop and irrigation applications, and other decision tools. Our focus is on the CSU Water Irrigation Scheduler for Efficient (WISE) Application tool, crop yield models, and remote soil moisture characterization as a demonstration of how complex fine-scale phytobiome processes and methods can be linked to weather and environmental remote sensing data sets in near real-time using scalable technologies.

  2. Breed locally, disperse globally: fine-scale genetic structure despite landscape-scale panmixia in a fire-specialist.

    PubMed

    Pierson, Jennifer C; Allendorf, Fred W; Drapeau, Pierre; Schwartz, Michael K

    2013-01-01

    An exciting advance in the understanding of metapopulation dynamics has been the investigation of how populations respond to ephemeral patches that go 'extinct' during the lifetime of an individual. Previous research has shown that this scenario leads to genetic homogenization across large spatial scales. However, little is known about fine-scale genetic structuring or how this changes over time in ephemeral patches. We predicted that species that specialize on ephemeral habitats will delay dispersal to exploit natal habitat patches while resources are plentiful and thus display fine-scale structure. To investigate this idea, we evaluated the effect of frequent colonization of ephemeral habitats on the fine-scale genetic structure of a fire specialist, the black-backed woodpecker (Picoides arcticus) and found a pattern of fine-scale genetic structure. We then tested for differences in spatial structure between sexes and detected a pattern consistent with male-biased dispersal. We also detected a temporal increase in relatedness among individuals within newly burned forest patches. Our results indicate that specialist species that outlive their ephemeral patches can accrue significant fine-scale spatial structure that does not necessarily affect spatial structure at larger scales. This highlights the importance of both spatial and temporal scale considerations in both sampling and data interpretation of molecular genetic results.

  3. Breed Locally, Disperse Globally: Fine-Scale Genetic Structure Despite Landscape-Scale Panmixia in a Fire-Specialist

    PubMed Central

    Pierson, Jennifer C.; Allendorf, Fred W.; Drapeau, Pierre; Schwartz, Michael K.

    2013-01-01

    An exciting advance in the understanding of metapopulation dynamics has been the investigation of how populations respond to ephemeral patches that go ‘extinct’ during the lifetime of an individual. Previous research has shown that this scenario leads to genetic homogenization across large spatial scales. However, little is known about fine-scale genetic structuring or how this changes over time in ephemeral patches. We predicted that species that specialize on ephemeral habitats will delay dispersal to exploit natal habitat patches while resources are plentiful and thus display fine-scale structure. To investigate this idea, we evaluated the effect of frequent colonization of ephemeral habitats on the fine-scale genetic structure of a fire specialist, the black-backed woodpecker (Picoides arcticus) and found a pattern of fine-scale genetic structure. We then tested for differences in spatial structure between sexes and detected a pattern consistent with male-biased dispersal. We also detected a temporal increase in relatedness among individuals within newly burned forest patches. Our results indicate that specialist species that outlive their ephemeral patches can accrue significant fine-scale spatial structure that does not necessarily affect spatial structure at larger scales. This highlights the importance of both spatial and temporal scale considerations in both sampling and data interpretation of molecular genetic results. PMID:23825646

  4. Clonal growth and fine-scale genetic structure in tanoak (Notholithocarpus densiflorus: Fagaceae).

    PubMed

    Dodd, Richard S; Mayer, Wasima; Nettel, Alejandro; Afzal-Rafii, Zara

    2013-01-01

    The combination of sprouting and reproduction by seed can have important consequences on fine-scale spatial distribution of genetic structure (SGS). SGS is an important consideration for species' restoration because it determines the minimum distance among seed trees to maximize genetic diversity while not prejudicing locally adapted genotypes. Local environmental conditions can be expected to influence levels of clonal spread and SGS, particularly in the case of disturbance regimes such as fire. Here, we characterize fine-scale genetic structure and clonal spread in tanoak from drier upland sites and more mesic lowland woodlands. Clonal spread was a significant mode of stand development, but spread was limited on average to about 5-6 m. Gene dispersal was decomposed into clonal and sexual components. The latter varied according to whether it was estimated from all ramets with the clonal component removed or for a single ramet per genet. We used the difference in these 2 estimates of gene dispersal as a measure of the effect of clonality on effective population size in this species. Although upland sites had a greater number of ramets per genet, most of the other indices computed were not significantly different. However, they tended to show greater heterozygote excess and shorter gene dispersal distances than the lowland sites. The average distance among inferred sibships on upland sites was approximately at the scale of maximum clonal range. This was not the case on lowland sites, where sibs were more dispersed. We recommend minimum distances among seed trees to avoid selecting clones and to maximize genetic diversity for restoration.

  5. Lack of sex-biased dispersal promotes fine-scale genetic structure in alpine ungulates

    USGS Publications Warehouse

    Roffler, Gretchen H.; Talbot, Sandra L.; Luikart, Gordon; Sage, George K.; Pilgrim, Kristy L.; Adams, Layne G.; Schwartz, Michael K.

    2014-01-01

    Identifying patterns of fine-scale genetic structure in natural populations can advance understanding of critical ecological processes such as dispersal and gene flow across heterogeneous landscapes. Alpine ungulates generally exhibit high levels of genetic structure due to female philopatry and patchy configuration of mountain habitats. We assessed the spatial scale of genetic structure and the amount of gene flow in 301 Dall’s sheep (Ovis dalli dalli) at the landscape level using 15 nuclear microsatellites and 473 base pairs of the mitochondrial (mtDNA) control region. Dall’s sheep exhibited significant genetic structure within contiguous mountain ranges, but mtDNA structure occurred at a broader geographic scale than nuclear DNA within the study area, and mtDNA structure for other North American mountain sheep populations. No evidence of male-mediated gene flow or greater philopatry of females was observed; there was little difference between markers with different modes of inheritance (pairwise nuclear DNA F ST = 0.004–0.325; mtDNA F ST = 0.009–0.544), and males were no more likely than females to be recent immigrants. Historical patterns based on mtDNA indicate separate northern and southern lineages and a pattern of expansion following regional glacial retreat. Boundaries of genetic clusters aligned geographically with prominent mountain ranges, icefields, and major river valleys based on Bayesian and hierarchical modeling of microsatellite and mtDNA data. Our results suggest that fine-scale genetic structure in Dall’s sheep is influenced by limited dispersal, and structure may be weaker in populations occurring near ancestral levels of density and distribution in continuous habitats compared to other alpine ungulates that have experienced declines and marked habitat fragmentation.

  6. Outlier SNP markers reveal fine-scale genetic structuring across European hake populations (Merluccius merluccius).

    PubMed

    Milano, Ilaria; Babbucci, Massimiliano; Cariani, Alessia; Atanassova, Miroslava; Bekkevold, Dorte; Carvalho, Gary R; Espiñeira, Montserrat; Fiorentino, Fabio; Garofalo, Germana; Geffen, Audrey J; Hansen, Jakob H; Helyar, Sarah J; Nielsen, Einar E; Ogden, Rob; Patarnello, Tomaso; Stagioni, Marco; Tinti, Fausto; Bargelloni, Luca

    2014-01-01

    Shallow population structure is generally reported for most marine fish and explained as a consequence of high dispersal, connectivity and large population size. Targeted gene analyses and more recently genome-wide studies have challenged such view, suggesting that adaptive divergence might occur even when neutral markers provide genetic homogeneity across populations. Here, 381 SNPs located in transcribed regions were used to assess large- and fine-scale population structure in the European hake (Merluccius merluccius), a widely distributed demersal species of high priority for the European fishery. Analysis of 850 individuals from 19 locations across the entire distribution range showed evidence for several outlier loci, with significantly higher resolving power. While 299 putatively neutral SNPs confirmed the genetic break between basins (F(CT) = 0.016) and weak differentiation within basins, outlier loci revealed a dramatic divergence between Atlantic and Mediterranean populations (F(CT) range 0.275-0.705) and fine-scale significant population structure. Outlier loci separated North Sea and Northern Portugal populations from all other Atlantic samples and revealed a strong differentiation among Western, Central and Eastern Mediterranean geographical samples. Significant correlation of allele frequencies at outlier loci with seawater surface temperature and salinity supported the hypothesis that populations might be adapted to local conditions. Such evidence highlights the importance of integrating information from neutral and adaptive evolutionary patterns towards a better assessment of genetic diversity. Accordingly, the generated outlier SNP data could be used for tackling illegal practices in hake fishing and commercialization as well as to develop explicit spatial models for defining management units and stock boundaries. © 2013 John Wiley & Sons Ltd.

  7. Fine-scale spatial genetic structure and dispersal among spotted salamander (Ambystoma maculatum) breeding populations.

    PubMed

    Zamudio, Kelly R; Wieczorek, Ania M

    2007-01-01

    We examined fine-scale genetic variation among breeding aggregations of the spotted salamander (Ambystoma maculatum) to quantify dispersal, interpopulation connectivity and population genetic structure. Spotted salamanders rely on temporary ponds or wetlands for aggregate breeding. Adequate breeding sites are relatively isolated from one another and field studies suggest considerable adult site fidelity; therefore, we expected to find population structure and differentiation at small spatial scales. We used microsatellites to estimate population structure and dispersal among 29 breeding aggregations in Tompkins County, New York, USA, an area encompassing 1272 km(2). Bayesian and frequency-based analyses revealed fine-scale genetic structure with two genetically defined demes: the North deme included seven breeding ponds, and the South deme included 13 ponds. Nine ponds showed evidence of admixture between these two genetic pools. Bayesian assignment tests for detection of interpopulation dispersal indicate that immigration among ponds is common within demes, and that certain populations serve as sources of immigrants to neighbouring ponds. Likewise, spatial genetic correlation analyses showed that populations < or = 4.8 km distant from each other show significant genetic correlation that is not evident at higher scales. Within-population levels of relatedness are consistently larger than expected if mating were completely random across ponds, and in the case of a few ponds, within-population processes such as inbreeding or reproductive skew contribute significantly to differentiation from neighbouring ponds. Our data underscore the importance of these within-population processes as a source of genetic diversity across the landscape, despite considerable population connectivity. Our data further suggest that spotted salamander breeding groups behave as metapopulations, with population clusters as functional units, but sufficient migration among demes to allow for

  8. Fine-scale features on bioreplicated decoys of the emerald ash borer provide necessary visual verisimilitude

    NASA Astrophysics Data System (ADS)

    Domingue, Michael J.; Pulsifer, Drew P.; Narkhede, Mahesh S.; Engel, Leland G.; Martín-Palma, Raúl J.; Kumar, Jayant; Baker, Thomas C.; Lakhtakia, Akhlesh

    2014-03-01

    The emerald ash borer (EAB), Agrilus planipennis, is an invasive tree-killing pest in North America. Like other buprestid beetles, it has an iridescent coloring, produced by a periodically layered cuticle whose reflectance peaks at 540 nm wavelength. The males perform a visually mediated ritualistic mating flight directly onto females poised on sunlit leaves. We attempted to evoke this behavior using artificial visual decoys of three types. To fabricate decoys of the first type, a polymer sheet coated with a Bragg-stack reflector was loosely stamped by a bioreplicating die. For decoys of the second type, a polymer sheet coated with a Bragg-stack reflector was heavily stamped by the same die and then painted green. Every decoy of these two types had an underlying black absorber layer. Decoys of the third type were produced by a rapid prototyping machine and painted green. Fine-scale features were absent on the third type. Experiments were performed in an American ash forest infested with EAB, and a European oak forest home to a similar pest, the two-spotted oak borer (TSOB), Agrilus biguttatus. When pinned to leaves, dead EAB females, dead TSOB females, and bioreplicated decoys of both types often evoked the complete ritualized flight behavior. Males also initiated approaches to the rapidly prototyped decoy, but would divert elsewhere without making contact. The attraction of the bioreplicated decoys was also demonstrated by providing a high dc voltage across the decoys that stunned and killed approaching beetles. Thus, true bioreplication with fine-scale features is necessary to fully evoke ritualized visual responses in insects, and provides an opportunity for developing insecttrapping technologies.

  9. Fine-scale chemical exposure differs in point and nonpoint source plumes.

    PubMed

    Lahman, Sara E; Moore, Paul A

    2015-05-01

    Increasing influxes of anthropogenic chemicals into aquatic ecosystems has led to growing global concern surrounding human and ecosystem health. As more freshwater systems are deemed not potable or usable for agricultural purposes, more attention is being paid to remediation and mitigation efforts. Predicting and preventing the impacts of the chemical inputs first requires a thorough understanding of the spatio-temporal distribution of chemical plumes in natural habitats. Plume dispersion is intimately tied to fluid mechanics; therefore, alterations in the way that chemical plumes are introduced to habitats can have profound effects on chemical distribution. Such alterations can subsequently alter the exposure to which organisms are subjected. This study examined the influence of point versus nonpoint sources in structuring the distribution of chemicals in a simulated flowing freshwater habitat. The fine-scale (molecular) spatio-temporal distribution of chemicals was measured in situ using an electrochemical detector. Molecular concentration at varying distance and height from the source was quantified using dopamine coupled with an electrochemical detection system. The fine-scale distribution of chemical plumes from point and nonpoint sources showed significant differences in how organisms will be exposed to chemicals. Overall, this study characterized plumes from nonpoint sources as having significantly longer peak lengths and rise times as well as greater peak heights and maximum slopes than plumes from point sources, thus providing a significantly different exposure paradigm. This quantification of how chemicals move differently throughout a fluid medium when introduced from point and nonpoint sources allows a greater understanding of how chemical plumes can potentially affect aquatic ecosystems.

  10. An Improvement of Fine Scale Wind Field Prediction using WRF/MMIF Models for CALPUFF Application.

    NASA Astrophysics Data System (ADS)

    Kim, A. L.; Koo, Y. S.

    2014-12-01

    Accurate simulation of CALPUFF dispersion modeling is largely dependent on the data sets which are properly resolved in the spatial and temporal evolution of meteorological field on a wide range of scales. The fine scale field wind of 100 m spatial resolution is required for the CALPUFF modeling in the complex terrain near the coastal area. The objective of this paper is to provide information how to calculate the fine scale wind field using recent advances in the meteorological model. The diagnostic model of CALMET has been used to generate fine grid scale wind field by interpolating output of mesoscale prognostic weather models of MM5 (short for Fifth-Generation Penn State/NCAR Mesoscale Model) and WRF (Weather Research and Forecast). The MMIF(The Mesoscale Model Interface Program) interfacial program directly converting WRF meteorological output to formats appropriate for CALPUFF modeling without diagnostic interpolations is recently developed. The modeling comparison between WRF/CALMET and WRF/MMIF was carried out to find out a best way in generating fine wind field in the complex geological conditions. For the WRF/CALMET modeling, WRF model output of 900m grid resolution was provided to CALMET model and CALMET then calculated the fine grid resolution of 100m by diagnostically interpolating the WRF output. For the WRF/MMIF modeling, the WRF model directly calculate the fine grid of 100m and the MMIF program was used to convert WRF data. In order to validate model performance of two methods, simulated variables of meteorological fields were compared with observations at the landfill site near the coast in KOREA. It is found that WRF/MMIF is in better agreement with observations than CALWRF/CALMET in respect to the statics of RMSE and IOA. CALPUFF modeling with landfill emission data of H2S was performed and compared with monitoring data to identify effects on meteorological data on the final outcome of CALPUFF dispersion modeling.

  11. Fine-scale genetic structure among greater sage-grouse leks in central Nevada.

    PubMed

    Jahner, Joshua P; Gibson, Daniel; Weitzman, Chava L; Blomberg, Erik J; Sedinger, James S; Parchman, Thomas L

    2016-06-14

    Mating systems that reduce dispersal and lead to non-random mating might increase the potential for genetic structure to arise at fine geographic scales. Greater sage-grouse (Centrocercus urophasianus) have a lek-based mating system and exhibit high site fidelity and skewed mating ratios. We quantified population structure by analyzing variation at 27,866 single-nucleotide polymorphisms in 140 males from ten leks (within five lek complexes) occurring in a small geographic region in central Nevada. Lek complexes, and to a lesser extent individual leks, formed statistically identifiable clusters in ordination analyses, providing evidence for fine-scale geographic genetic differentiation. Lek geography predicted genetic differentiation even at a small geographic scale, which could be sharpened by strong site fidelity. Relatedness was also higher among individuals within lek complexes (and leks), suggesting that reproductive skew, where few males participate in most of the successful matings, could also potentially contribute to genetic differentiation. Models incorporating a habitat resistance surface as a proxy for potentially reduced movement due to landscape features indicated that both geographic distance and habitat suitability (i.e. preferred habitat) predicted genetic structure, with no significant effect of man-made barriers to movement (i.e. power lines and roads). Finally, we illustrate how data sets containing fewer loci (<4000) had less statistical precision and failed to detect the full degree of genetic structure. Our results suggest that habitat features and lek site geography of sage-grouse shape fine scale genetic structure, and highlight how larger data sets can have increased precision and accuracy for quantifying ecologically relevant genetic structure over small geographic scales.

  12. Forest age correlates with fine-scale spatial structure of Matsutake mycorrhizas.

    PubMed

    Amend, Anthony; Keeley, Sterling; Garbelotto, Matteo

    2009-05-01

    Examining the fine-scale spatial structure of fungal populations can tell us much about how individual species reproduce and disperse throughout natural landscapes. Here we study the fine-scale genetic structure of Tricholoma matsutake, a prized edible and medicinal mushroom, by systematic sampling of mycorrhizas within fairy rings in 50-y-old and old-growth forests in two villages. Using single nucleotide polymorphism DNA markers we show that mycorrhizas in both forest age classes in both villages showed high levels of genotypic diversity, consistent with a reproductive life history predominated by outcrossing via basidiospore dispersal. Both the percentage of polymorphic loci within fairy rings, as well as genotype diversity were higher in old-growth compared to 50-y-old forests. Fifty-year-old forests showed significant spatial autocorrelation between pairs of mycorrhizas up to 42m, and a pattern consistent isolation-by-distance structure. Spatial patterns in old-growth forests were random. Furthermore, AMOVA analysis indicates that 11% of molecular variance in 50-y-old forests is partitioned between villages, whereas no significant variance is partitioned between villages in old-growth forests. We conclude that populations of T. matsutake in 50-y-old forests are the result of a founder effect maintained by local inoculation sources. This pattern attenuates as forests age and accumulate inocula from more distance sources. We speculate on how genetic mosaicism within T. matsutake fairy rings may structure populations within a chronosequence. Finally, we discuss how population spatial dynamics and dispersal strategy in T. matsutake contrast with other ectomycorrhizal species.

  13. Persistent fine-scale fault structures control rupture development in Parkfield, CA.

    NASA Astrophysics Data System (ADS)

    Perrin, C.; Waldhauser, F.; Scholz, C. H.

    2016-12-01

    We investigate the fine-scale geometry and structure of the San Andreas Fault (SAF) near Parkfield, CA, and their role in the development of the 1966 and 2004 M6 earthquakes. Both events broke the fault mainly unilaterally with similar length ( 30 km) but in opposite directions. Seismic slip occurred in a narrow zone between 5 and 10 km depth, as outlined by the concentration of aftershocks along the edge of the slip area. Across fault distribution of the 2004 aftershocks show a rapid decrease of event density away from the fault core. The damage zone is narrower in the Parkfield section (few 100 meters) than in the creeping section ( 1 km). We observe a similar but broader distribution during the interseismic periods. This implies that stress accumulates in a volume around the fault during interseismic periods, whereas coseismic deformation is more localized on the mature SAF. Large aftershocks are concentrated at both rupture tips, characterized by strong heterogeneities in the fault structure at the surface and at depth: i) in the south near Gold Hill-Cholame, a large releasing bend (>25°) separates the Parkfield section from the southern section of the SAF; ii) in the north at Middle Mountain, the surface fault trace goes through an ancient restraining step-over connecting the Parkfield and creeping sections. Fine-scale analysis of the 2004 aftershocks reveals a change in the fault dip and local variations of the fault strike (up to 25°) beneath Middle Mountain, in good agreement with focal mechanisms, which show oblique normal and reverse faulting. We observe these variations during the interseismic periods before and after the 2004 event, suggesting that the structural heterogeneities persisted through at least two earthquake cycles. These heterogeneities act as barriers to rupture propagation of moderate size earthquakes at Parkfield, but also as stress concentrations where rupture initiates.

  14. Unresolved Fine-scale Structure in Solar Coronal Loop-tops

    NASA Astrophysics Data System (ADS)

    Scullion, E.; Rouppe van der Voort, L.; Wedemeyer, S.; Antolin, P.

    2014-12-01

    New and advanced space-based observing facilities continue to lower the resolution limit and detect solar coronal loops in greater detail. We continue to discover even finer substructures within coronal loop cross-sections, in order to understand the nature of the solar corona. Here, we push this lower limit further to search for the finest coronal loop substructures, through taking advantage of the resolving power of the Swedish 1 m Solar Telescope/CRisp Imaging Spectro-Polarimeter (CRISP), together with co-observations from the Solar Dynamics Observatory/Atmospheric Image Assembly (AIA). High-resolution imaging of the chromospheric Hα 656.28 nm spectral line core and wings can, under certain circumstances, allow one to deduce the topology of the local magnetic environment of the solar atmosphere where its observed. Here, we study post-flare coronal loops, which become filled with evaporated chromosphere that rapidly condenses into chromospheric clumps of plasma (detectable in Hα) known as a coronal rain, to investigate their fine-scale structure. We identify, through analysis of three data sets, large-scale catastrophic cooling in coronal loop-tops and the existence of multi-thermal, multi-stranded substructures. Many cool strands even extend fully intact from loop-top to footpoint. We discover that coronal loop fine-scale strands can appear bunched with as many as eight parallel strands within an AIA coronal loop cross-section. The strand number density versus cross-sectional width distribution, as detected by CRISP within AIA-defined coronal loops, most likely peaks at well below 100 km, and currently, 69% of the substructure strands are statistically unresolved in AIA coronal loops.

  15. Fine-scale features on the sea surface in SAR satellite imagery - Part 2: Numerical modeling

    NASA Astrophysics Data System (ADS)

    Matt, S.; Fujimura, A.; Soloviev, A.; Rhee, S. H.; Romeiser, R.

    2014-06-01

    With the advent of the new generation of synthetic aperture radar (SAR) satellites, it has become possible to resolve fine-scale features on the sea surface on the scale of meters. The proper identification of sea surface signatures in SAR imagery can be challenging, since some features may be due to atmospheric distortions (gravity waves, squall lines) or anthropogenic influences (slicks), and may not be related to dynamic processes in the upper ocean. In order to improve our understanding of the nature of fine-scale features on the sea surface and their signature in SAR, we have conducted high-resolution numerical simulations combining a three-dimensional non-hydrostatic computational fluid dynamics model with a radar imaging model. The surface velocity field from the hydrodynamic model is used as input to the radar imaging model. The combined approach reproduces the sea surface signatures in SAR of ship wakes, low-density plumes, and internal waves in a stratified environment. The numerical results are consistent with observations reported in a companion paper on in situ measurements during SAR satellite overpasses. Ocean surface and internal waves are also known to produce a measurable signal in the ocean magnetic field. This paper explores the use of computational fluid dynamics to investigate the magnetic signatures of oceanic processes. This potentially provides a link between SAR signatures of transient ocean dynamics and magnetic field fluctuations in the ocean. We suggest that combining SAR imagery with data from ocean magnetometers may be useful as an additional maritime sensing method. The new approach presented in this work can be extended to other dynamic processes in the upper ocean, including fronts and eddies, and can be a valuable tool for the interpretation of SAR images of the ocean surface.

  16. Fine-scale features on the sea surface in SAR satellite imagery - Part 2: Numerical modeling

    NASA Astrophysics Data System (ADS)

    Matt, S.; Fujimura, A.; Soloviev, A.; Rhee, S. H.; Romeiser, R.

    2012-09-01

    With the advent of the new generation of SAR satellites, it has become possible to resolve fine-scale features on the sea surface on the scale of meters. The proper identification of sea surface signatures in SAR imagery can be challenging, since some features may be due to atmospheric distortions (gravity waves, squall lines) or anthropogenic influences (slicks), and may not be related to dynamic processes in the upper ocean. In order to improve our understanding of the nature of fine-scale features on the sea surface and their signature in SAR, we have conducted high-resolution numerical simulations combining a three-dimensional non-hydrostatic computational fluid dynamics model with a radar imaging model. The surface velocity field from the hydrodynamic model is used as input to the radar imaging model. The combined approach reproduces the sea surface signatures in SAR of ship wakes, low density plumes, and internal waves in a stratified environment. The numerical results are consistent with observations reported in a companion paper of in-situ measurements during SAR satellite overpasses. Ocean surface and internal waves are also known to produce a measurable signal in the ocean magnetic field. This paper explores the use of computational fluid dynamics to investigate the magnetic signatures of oceanic processes. This potentially provides a link between SAR signatures of transient ocean dynamics and magnetic field fluctuations in the ocean. We suggest that combining SAR imagery with data from ocean magnetometers may be useful as an additional maritime sensing method. The new approach presented in this work can be extended to other dynamic processes in the upper ocean, including fronts and eddies, and can be a valuable tool for the interpretation of SAR images of the ocean surface.

  17. Investigations of fine-scale phylogeography in Tigriopus californicus reveal historical patterns of population divergence.

    PubMed

    Willett, Christopher S; Ladner, Jason T

    2009-06-23

    The intertidal copepod Tigriopus californicus is a model for studying the process of genetic divergence in allopatry and for probing the nature of genetic changes that lead to reproductive isolation. Although previous studies have revealed a pattern of remarkably high levels of genetic divergence between the populations of this species at several spatial scales, it is not clear what types of historical processes are responsible. Particularly lacking are data that can yield insights into population history from the finest scales of geographic resolution. Sequence variation in both cytochrome b (CYTB, mtDNA) and the rieske iron-sulfur protein (RISP, nuclear) are examined at a fine scale within four different regions for populations of T. californicus. High levels of genetic divergence are seen for both genes at the broader scale, and genetic subdivision is apparent at nearly all scales in these populations for these two genes. Patterns of polymorphism and divergence in both CYTB and RISP suggest that selection may be leading to non-neutral evolution of these genes in several cases but a pervasive pattern of neither selection nor coadaptation is seen for these markers. The use of sequence data at a fine-scale of resolution in this species has provided novel insights into the processes that have resulted in the accumulation of genetic divergence among populations. This divergence is likely to result from an interplay between a limited dispersal ability for this copepod and the temporal instability of copepod habitat. Both shorter-term processes such as the extinction/recolonization dynamics of copepod pools and longer-term processes such as geological uplift of coastline and sea level changes appear to have impacted the patterns of differentiation. Some patterns of sequence variation are consistent with selection acting upon the loci used in this study; however, it appears that most phylogeographic patterns are the result of history and not selection on these genes in

  18. Investigations of fine-scale phylogeography in Tigriopus californicus reveal historical patterns of population divergence

    PubMed Central

    Willett, Christopher S; Ladner, Jason T

    2009-01-01

    Background The intertidal copepod Tigriopus californicus is a model for studying the process of genetic divergence in allopatry and for probing the nature of genetic changes that lead to reproductive isolation. Although previous studies have revealed a pattern of remarkably high levels of genetic divergence between the populations of this species at several spatial scales, it is not clear what types of historical processes are responsible. Particularly lacking are data that can yield insights into population history from the finest scales of geographic resolution. Results Sequence variation in both cytochrome b (CYTB, mtDNA) and the rieske iron-sulfur protein (RISP, nuclear) are examined at a fine scale within four different regions for populations of T. californicus. High levels of genetic divergence are seen for both genes at the broader scale, and genetic subdivision is apparent at nearly all scales in these populations for these two genes. Patterns of polymorphism and divergence in both CYTB and RISP suggest that selection may be leading to non-neutral evolution of these genes in several cases but a pervasive pattern of neither selection nor coadaptation is seen for these markers. Conclusion The use of sequence data at a fine-scale of resolution in this species has provided novel insights into the processes that have resulted in the accumulation of genetic divergence among populations. This divergence is likely to result from an interplay between a limited dispersal ability for this copepod and the temporal instability of copepod habitat. Both shorter-term processes such as the extinction/recolonization dynamics of copepod pools and longer-term processes such as geological uplift of coastline and sea level changes appear to have impacted the patterns of differentiation. Some patterns of sequence variation are consistent with selection acting upon the loci used in this study; however, it appears that most phylogeographic patterns are the result of history and

  19. Unresolved fine-scale structure in solar coronal loop-tops

    SciTech Connect

    Scullion, E.; Van der Voort, L. Rouppe; Wedemeyer, S.; Antolin, P.

    2014-12-10

    New and advanced space-based observing facilities continue to lower the resolution limit and detect solar coronal loops in greater detail. We continue to discover even finer substructures within coronal loop cross-sections, in order to understand the nature of the solar corona. Here, we push this lower limit further to search for the finest coronal loop substructures, through taking advantage of the resolving power of the Swedish 1 m Solar Telescope/CRisp Imaging Spectro-Polarimeter (CRISP), together with co-observations from the Solar Dynamics Observatory/Atmospheric Image Assembly (AIA). High-resolution imaging of the chromospheric Hα 656.28 nm spectral line core and wings can, under certain circumstances, allow one to deduce the topology of the local magnetic environment of the solar atmosphere where its observed. Here, we study post-flare coronal loops, which become filled with evaporated chromosphere that rapidly condenses into chromospheric clumps of plasma (detectable in Hα) known as a coronal rain, to investigate their fine-scale structure. We identify, through analysis of three data sets, large-scale catastrophic cooling in coronal loop-tops and the existence of multi-thermal, multi-stranded substructures. Many cool strands even extend fully intact from loop-top to footpoint. We discover that coronal loop fine-scale strands can appear bunched with as many as eight parallel strands within an AIA coronal loop cross-section. The strand number density versus cross-sectional width distribution, as detected by CRISP within AIA-defined coronal loops, most likely peaks at well below 100 km, and currently, 69% of the substructure strands are statistically unresolved in AIA coronal loops.

  20. Oscillatory thermocapillary convection

    NASA Technical Reports Server (NTRS)

    Mundrane, Michael R.; Zebib, Abdelfattah

    1994-01-01

    We study thermocapillary and buoyant thermocapillary convection in rectangular cavities with aspect ratio A = 4 and Pr = 0.015. Two separate problems are considered. The first is combined buoyant thermocapillary convection with a nondeforming interface. We establish neutral curves for transition to oscillatory convection in the Re-Gr plane. It is shown that while pure buoyant convection exhibits oscillatory behavior for Gr is greater than Gr(sub cr) (where Gr(sub cr) is defined for the pure buoyant problem), pure thermocapillary convection is steady within the range of parameters tested. In the second problem, we consider the influence of surface deformation on the pure thermocapillary problem. For the range of parameters considered, thermocapillary convection remained steady.

  1. Binary Oscillatory Crossflow Electrophoresis

    NASA Technical Reports Server (NTRS)

    Molloy, Richard F.; Gallagher, Christopher T.; Leighton, David T., Jr.

    1997-01-01

    Electrophoresis has long been recognized as an effective analytic technique for the separation of proteins and other charged species, however attempts at scaling up to accommodate commercial volumes have met with limited success. In this report we describe a novel electrophoretic separation technique - Binary Oscillatory Crossflow Electrophoresis (BOCE). Numerical simulations indicate that the technique has the potential for preparative scale throughputs with high resolution, while simultaneously avoiding many problems common to conventional electrophoresis. The technique utilizes the interaction of an oscillatory electric field and a transverse oscillatory shear flow to create an active binary filter for the separation of charged protein species. An oscillatory electric field is applied across the narrow gap of a rectangular channel inducing a periodic motion of charged protein species. The amplitude of this motion depends on the dimensionless electrophoretic mobility, alpha = E(sub o)mu/(omega)d, where E(sub o) is the amplitude of the electric field oscillations, mu is the dimensional mobility, omega is the angular frequency of oscillation and d is the channel gap width. An oscillatory shear flow is induced along the length of the channel resulting in the separation of species with different mobilities. We present a model that predicts the oscillatory behavior of charged species and allows estimation of both the magnitude of the induced convective velocity and the effective diffusivity as a function of a in infinitely long channels. Numerical results indicate that in addition to the mobility dependence, the steady state behavior of solute species may be strongly affected by oscillating fluid into and out of the active electric field region at the ends of the cell. The effect is most pronounced using time dependent shear flows of the same frequency (cos((omega)t)) flow mode) as the electric field oscillations. Under such conditions, experiments indicate that

  2. Fine-scale density wave structure of Saturn's A and B rings: Theory and simulations

    NASA Astrophysics Data System (ADS)

    Griv, Evgeny

    We examine the linear stability of the Saturnian ring disk of mutually gravitating and physically colliding particles with special emphasis on its fine-scale of the order of 100 m density wave structure, that is, almost regularly spaced, aligned cylindric density enhancements and optically-thin zones with the width and the spacing between them of roughly several tens particle diameters. We analyze the Jeans’ instabilities of gravity perturbations (e.g. those produced by a spontaneous disturbance) analytically by using the Navier-Stokes dynamical equations of a compressible fluid. For the first time in planetary ring dynamics, the theory is not restricted by any assumptions about the thickness of the system. We consider a simple model of the system consisting of a three-dimensional ring disk that is weakly inhomogeneous and whose structure is analyzed by making a horizontally local short-wave approximation. We demonstrate that the disk is Jeans-unstable and that gravity perturbations grow effectively within a few orbital periods. We find that self-gravitation plays a key role in the formation of the fine structure. The predictions of the theory are compared with observations of Saturn’s rings by the Cassini spacecraft and are found to be in good agreement. In particular, it appears very likely that some of the quasi-periodic microstructures observed in Saturn’s A and B rings - both axisymmetric and nonaxisymmetric ones - are manifestations of these effects. Thus, one can attribute the fine-scale structure observed in Saturn’s A and B rings in Cassini data to the development of free Lin-Shu type compression waves, or density waves -- normal modes -- developing in the plane of the system. From the well-developed theory of galactic spiral density waves, a free density wave is known to rotate in a rigid-body manner and to not be affected by differential rotation of the ring disk. We argue that the quasi-periodic density enhancements revealed in Cassini data are

  3. Novel laboratory methods for determining the fine scale electrical resistivity structure of core

    NASA Astrophysics Data System (ADS)

    Haslam, E. P.; Gunn, D. A.; Jackson, P. D.; Lovell, M. A.; Aydin, A.; Prance, R. J.; Watson, P.

    2014-12-01

    High-resolution electrical resistivity measurements are made on saturated rocks using novel laboratory instrumentation and multiple electrical voltage measurements involving in principle a four-point electrode measurement but with a single, moving electrode. Flat, rectangular core samples are scanned by varying the electrode position over a range of hundreds of millimetres with an accuracy of a tenth of a millimetre. Two approaches are tested involving a contact electrode and a non-contact electrode arrangement. The first galvanic method uses balanced cycle switching of a floating direct current (DC) source to minimise charge polarisation effects masking the resistivity distribution related to fine scale structure. These contacting electrode measurements are made with high common mode noise rejection via differential amplification with respect to a reference point within the current flow path. A computer based multifunction data acquisition system logs the current through the sample and voltages along equipotentials from which the resistivity measurements are derived. Multiple measurements are combined to create images of the surface resistivity structure, with variable spatial resolution controlled by the electrode spacing. Fine scale sedimentary features and open fractures in saturated rocks are interpreted from the measurements with reference to established relationships between electrical resistivity and porosity. Our results successfully characterise grainfall lamination and sandflow cross-stratification in a brine saturated, dune bedded core sample representative of a southern North Sea reservoir sandstone, studied using the system in constant current, variable voltage mode. In contrast, in a low porosity marble, identification of open fracture porosity against a background very low matrix porosity is achieved using the constant voltage, variable current mode. This new system is limited by the diameter of the electrode that for practical reasons can only be

  4. Fine-Scale Density Wave Structure of Saturn's Main Rings: A Hydrodynamic Theory

    NASA Astrophysics Data System (ADS)

    Griv, Evgeny; Gedalin, Michael

    The theoretical studies of Maxwell (1859) have showed that the rings around Saturn could not be solid or liquid, but rather a swarm of millions of individual particles rotating in separate concentric orbits at different speeds. A modern very popular model of the particles in Saturn's rings is a smooth ice sphere, whose restitution coefficient is quite high (exceeding 0.63) and decreases as the collision velocity increases. In this work, the linear stability of the Saturnian ring disk of mutually gravitating and physically colliding particles is examined with special emphasis on its fine-scale of the order of 100 m density wave structure, that is, almost regularly spaced, aligned cylindric density enhancements and optically-thin zones with the width and the spacing between them of roughly several tens particle diameters. Jeans' instabilities of small-amplitude gravity perturbations (e.g., those produced by a spontaneous disturbance) are analyzed analytically through the use of Navier-Stokes dynamical equations of a compressible fluid. An essential feature of this study is that the theory is not restricted by any assumptions regarding the thickness of the system. The simple model of the system is considered: the ring disk is considered to be thin, a weakly spatially inhomogeneous, and its structure is considered in a horizontally local short-wave approximation. We show that the disk is probably unstable and gravity perturbations grow effectively within a few orbital periods; self-gravitation plays a key role in the formation of the fine-scale structure while particle collisions play a secondary role. The predictions of the theory are compared with recent observations of Saturn's rings by the Cassini spacecraft and are found to be in good agreement. Particulary, it appears very likely that some of the microstructures observed in Saturn's A and B rings -both axisymmetric and nonaxisymmetric ones -are manifestations of these effects produced by Jeans' gravitational

  5. Fine-Scale Relief in the Amazon Drives Large Scale Ecohydrological Processes

    NASA Astrophysics Data System (ADS)

    Nobre, A. D.; Cuartas, A.; Hodnett, M.; Saleska, S. R.

    2014-12-01

    Access to soil water by roots is a key ecophysiological factor for plant productivity in natural systems. Periodically during dry seasons or critically during episodic climate droughts, shortage of water supply can reduce or severely impair plant life. At the other extreme persistent soil waterlogging will limit root respiration and restrict local establishment to adapted species, usually leading to stunted and less productive communities. Soil-water availability is therefore a very important climate variable controlling plant physiology and ecosystem dynamics. Terra-firme, the non-seasonally floodable terrain that covers 82% of the landscape in Amazonia,[1] supports the most massive part of the rainforest ecosystem. The availability of soil water data for terra-firme is scant and very coarse. This lack of data has hampered observational and modeling studies aiming to develop a large-scale integrative ecohydrological picture of Amazonia and its vulnerability to climate change. We have mapped the Amazon basin with a new terrain model developed in our group (HAND, Height Above the Nearest drainage[2]), delineating soil water environments using topographical data from the SRTM digital elevation model (250 m horizontal interpolated resolution). The preliminary results show that more than 50% of Terra-firme has the water table very close to the surface (up to 2 m deep), while the remainder of the upland landscape has variable degree of dependence on non-saturated soil (vadose layer). The mapping also shows extremely heterogeneous patterns of fine-scale relief across the basin, which implies complex ecohydrological regional forcing on the forest physiology. Ecoclimate studies should therefore take into account fine-scale relief and its implications for soil-water availability to plant processes. [1] Melack, J. M., & Hess, L. L. (2011). Remote sensing of the distribution and extent of wetlands in the Amazon basin. In W. J. Junk & M. Piedade (Eds.), Amazonian floodplain

  6. On Time/Space Aggregation of Fine-Scale Error Estimates (Invited)

    NASA Astrophysics Data System (ADS)

    Huffman, G. J.

    2013-12-01

    Estimating errors inherent in fine time/space-scale satellite precipitation data sets is still an on-going problem and a key area of active research. Complicating features of these data sets include the intrinsic intermittency of the precipitation in space and time and the resulting highly skewed distribution of precipitation rates. Additional issues arise from the subsampling errors that satellites introduce, the errors due to retrieval algorithms, and the correlated error that retrieval and merger algorithms sometimes introduce. Several interesting approaches have been developed recently that appear to make progress on these long-standing issues. At the same time, the monthly averages over 2.5°x2.5° grid boxes in the Global Precipitation Climatology Project (GPCP) Satellite-Gauge (SG) precipitation data set follow a very simple sampling-based error model (Huffman 1997) with coefficients that are set using coincident surface and GPCP SG data. This presentation outlines the unsolved problem of how to aggregate the fine-scale errors (discussed above) to an arbitrary time/space averaging volume for practical use in applications, reducing in the limit to simple Gaussian expressions at the monthly 2.5°x2.5° scale. Scatter diagrams with different time/space averaging show that the relationship between the satellite and validation data improves due to the reduction in random error. One of the key, and highly non-linear, issues is that fine-scale estimates tend to have large numbers of cases with points near the axes on the scatter diagram (one of the values is exactly or nearly zero, while the other value is higher). Averaging 'pulls' the points away from the axes and towards the 1:1 line, which usually happens for higher precipitation rates before lower rates. Given this qualitative observation of how aggregation affects error, we observe that existing aggregation rules, such as the Steiner et al. (2003) power law, only depend on the aggregated precipitation rate

  7. Integrating fine-scale soil data into species distribution models: preparing Soil Survey Geographic (SSURGO) data from multiple counties

    Treesearch

    Matthew P. Peters; Louis R. Iverson; Anantha M. Prasad; Steve N. Matthews

    2013-01-01

    Fine-scale soil (SSURGO) data were processed at the county level for 37 states within the eastern United States, initially for use as predictor variables in a species distribution model called DISTRIB II. Values from county polygon files converted into a continuous 30-m raster grid were aggregated to 4-km cells and integrated with other environmental and site condition...

  8. Breed locally, disperse globally: Fine-scale genetic structure despite landscape-scale panmixia in a fire-specialist

    Treesearch

    Jennifer C. Pierson; Fred W. Allendorf; Pierre Drapeau; Michael K. Schwartz

    2013-01-01

    An exciting advance in the understanding of metapopulation dynamics has been the investigation of how populations respond to ephemeral patches that go 'extinct' during the lifetime of an individual. Previous research has shown that this scenario leads to genetic homogenization across large spatial scales. However, little is known about fine-scale genetic...

  9. Polygamy and an absence of fine-scale structure in Dendroctonus ponderosae (Hopk.) (Coleoptera: Curcilionidae) confirmed using molecular markers

    PubMed Central

    Janes, J K; Roe, A D; Rice, A V; Gorrell, J C; Coltman, D W; Langor, D W; Sperling, F A H

    2016-01-01

    An understanding of mating systems and fine-scale spatial genetic structure is required to effectively manage forest pest species such as Dendroctonus ponderosae (mountain pine beetle). Here we used genome-wide single-nucleotide polymorphisms to assess the fine-scale genetic structure and mating system of D. ponderosae collected from a single stand in Alberta, Canada. Fine-scale spatial genetic structure was absent within the stand and the majority of genetic variation was best explained at the individual level. Relatedness estimates support previous reports of pre-emergence mating. Parentage assignment tests indicate that a polygamous mating system better explains the relationships among individuals within a gallery than the previously reported female monogamous/male polygynous system. Furthermore, there is some evidence to suggest that females may exploit the galleries of other females, at least under epidemic conditions. Our results suggest that current management models are likely to be effective across large geographic areas based on the absence of fine-scale genetic structure. PMID:26286666

  10. Polygamy and an absence of fine-scale structure in Dendroctonus ponderosae (Hopk.) (Coleoptera: Curcilionidae) confirmed using molecular markers.

    PubMed

    Janes, J K; Roe, A D; Rice, A V; Gorrell, J C; Coltman, D W; Langor, D W; Sperling, F A H

    2016-01-01

    An understanding of mating systems and fine-scale spatial genetic structure is required to effectively manage forest pest species such as Dendroctonus ponderosae (mountain pine beetle). Here we used genome-wide single-nucleotide polymorphisms to assess the fine-scale genetic structure and mating system of D. ponderosae collected from a single stand in Alberta, Canada. Fine-scale spatial genetic structure was absent within the stand and the majority of genetic variation was best explained at the individual level. Relatedness estimates support previous reports of pre-emergence mating. Parentage assignment tests indicate that a polygamous mating system better explains the relationships among individuals within a gallery than the previously reported female monogamous/male polygynous system. Furthermore, there is some evidence to suggest that females may exploit the galleries of other females, at least under epidemic conditions. Our results suggest that current management models are likely to be effective across large geographic areas based on the absence of fine-scale genetic structure.

  11. FINE SCALE AIR QUALITY MODELING USING DISPERSION AND CMAQ MODELING APPROACHES: AN EXAMPLE APPLICATION IN WILMINGTON, DE

    EPA Science Inventory

    Characterization of spatial variability of air pollutants in an urban setting at fine scales is critical for improved air toxics exposure assessments, for model evaluation studies and also for air quality regulatory applications. For this study, we investigate an approach that su...

  12. Introducing close-range photogrammetry for characterizing forest understory plant diversity and surface fuel structure at fine scales

    Treesearch

    Benjamin C. Bright; E. Louise Loudermilk; Scott M. Pokswinski; Andrew T. Hudak; Joseph J. O' Brien

    2016-01-01

    Methods characterizing fine-scale fuels and plant diversity can advance understanding of plant-fire interactions across scales and help in efforts to monitor important ecosystems such as longleaf pine (Pinus palustris Mill.) forests of the southeastern United States. Here, we evaluate the utility of close-range photogrammetry for measuring fuels and plant...

  13. FINE SCALE AIR QUALITY MODELING USING DISPERSION AND CMAQ MODELING APPROACHES: AN EXAMPLE APPLICATION IN WILMINGTON, DE

    EPA Science Inventory

    Characterization of spatial variability of air pollutants in an urban setting at fine scales is critical for improved air toxics exposure assessments, for model evaluation studies and also for air quality regulatory applications. For this study, we investigate an approach that su...

  14. A New Multibeam Sonar Technique for Evaluating Fine-Scale Fish Behavior Near Hydroelectric Dam Guidance Structures

    SciTech Connect

    Johnson, Robert L.; Simmons, Mary Ann; Simmons, Carver S.; Blanton, Susan L.; Coutant, C.

    2002-03-07

    This book chapter describes a Dual-Head Multibeam Sonar (DHMS) system developed by Battelle and deployed at two dam sites on the Snake and Columbia rivers in Washington State to evaluate the fine-scale (

  15. RESOLVING FINE SCALE IN AIR TOXICS MODELING AND THE IMPORTANCE OF ITS SUB-GRID VARIABILITY FOR EXPOSURE ESTIMATES

    EPA Science Inventory

    This presentation explains the importance of the fine-scale features for air toxics exposure modeling. The paper presents a new approach to combine local-scale and regional model results for the National Air Toxic Assessment. The technique has been evaluated with a chemical tra...

  16. Evaluation of Species Distribution Model Algorithms For Fine-Scale Container Breeding Mosquito Risk Prediction

    PubMed Central

    Khatchikian, C.; Sangermano, F.; Kendell, D.; Livdahl, T.

    2010-01-01

    The present work evaluates the use of species distribution model (SDM) algorithms to classify high density of small container Aedes mosquitoes at a fine scale, in the Bermuda islands. Weekly ovitrap data collected by the Health Department of Bermuda (UK) for the years 2006 and 2007 were used for the models. The models evaluated included the following algorithms: Bioclim, Domain, GARP, logistic regression, and MaxEnt. Models were evaluated according to performance and robustness. The area Receiver Operating Characteristic (ROC) curve was used to evaluate each model’s performance, and robustness was assessed considering the spatial correlation between classification risks for the two datasets. Relative to the other algorithms, logistic regression was the best model for classifying high risk areas, and the maximum entropy approach (MaxEnt) presented the second best performance. We report the importance of covariables for these two models, and discuss the utility of SDMs for vector control efforts and the potential for the development of scripts that automate the task of creating risk assessment maps. PMID:21198711

  17. Fine-Scale Genetic Structure Arises during Range Expansion of an Invasive Gecko

    PubMed Central

    Short, Kristen Harfmann; Petren, Kenneth

    2011-01-01

    Processes of range expansion are increasingly important in light of current concerns about invasive species and range shifts due to climate change. Theoretical studies suggest that genetic structuring may occur during range expansion. Ephemeral genetic structure can have important evolutionary implications, such as propagating genetic changes along the wave front of expansion, yet few studies have shown evidence of such structure. We tested the hypothesis that genetic structure arises during range expansion in Hemidactylus mabouia, a nocturnal African gecko recently introduced to Florida, USA. Twelve highly variable microsatellite loci were used to screen 418 individuals collected from 43 locations from four sampling sites across Florida, representing a gradient from earlier (∼1990s) to very recent colonization. We found earlier colonized locations had little detectable genetic structure and higher allelic richness than more recently colonized locations. Genetic structuring was pronounced among locations at spatial scales of tens to hundreds of meters near the leading edge of range expansion. Despite the rapid pace of range expansion in this introduced gecko, dispersal is limited among many suitable habitat patches. Fine-scale genetic structure is likely the result of founder effects during colonization of suitable habitat patches. It may be obscured over time and by scale-dependent modes of dispersal. Further studies are needed to determine if such genetic structure affects adaptation and trait evolution in range expansions and range shifts. PMID:22053186

  18. Restricted gene flow and fine-scale population structuring in tool using New Caledonian crows

    NASA Astrophysics Data System (ADS)

    Rutz, C.; Ryder, T. B.; Fleischer, R. C.

    2012-04-01

    New Caledonian crows Corvus moneduloides are the most prolific avian tool users. It has been suggested that some aspects of their complex tool use behaviour are under the influence of cultural processes, involving the social transmission—and perhaps even progressive refinement—of tool designs. Using microsatellite and mt-haplotype profiling of crows from three distinct habitats (dry forest, farmland and beachside habitat), we show that New Caledonian crow populations can exhibit significant fine-scale genetic structuring. Our finding that some sites of <10 km apart were highly differentiated demonstrates considerable potential for genetic and/or cultural isolation of crow groups. Restricted movement of birds between local populations at such small spatial scales, especially across habitat boundaries, illustrates how specific tool designs could be preserved over time, and how tool technologies of different crow groups could diverge due to drift and local selection pressures. Young New Caledonian crows have an unusually long juvenile dependency period, during which they acquire complex tool-related foraging skills. We suggest that the resulting delayed natal dispersal drives population-divergence patterns in this species. Our work provides essential context for future studies that examine the genetic makeup of crow populations across larger geographic areas, including localities with suspected cultural differences in crow tool technologies.

  19. Fine-scale Horizontal Structure of Arctic Mixed-Phase Clouds.

    SciTech Connect

    Rambukkange,M.; Verlinde, J.; Elorante, E.; Luke, E.; Kollias, P.; Shupe, M.

    2006-07-10

    Recent in situ observations in stratiform clouds suggest that mixed phase regimes, here defined as limited cloud volumes containing both liquid and solid water, are constrained to narrow layers (order 100 m) separating all-liquid and fully glaciated volumes (Hallett and Viddaurre, 2005). The Department of Energy Atmospheric Radiation Measurement Program's (DOE-ARM, Ackerman and Stokes, 2003) North Slope of Alaska (NSA) ARM Climate Research Facility (ACRF) recently started collecting routine measurement of radar Doppler velocity power spectra from the Millimeter Cloud Radar (MMCR). Shupe et al. (2004) showed that Doppler spectra has potential to separate the contributions to the total reflectivity of the liquid and solid water in the radar volume, and thus to investigate further Hallett and Viddaurre's findings. The Mixed-Phase Arctic Cloud Experiment (MPACE) was conducted along the NSA to investigate the properties of Arctic mixed phase clouds (Verlinde et al., 2006). We present surface based remote sensing data from MPACE to discuss the fine-scale structure of the mixed-phase clouds observed during this experiment.

  20. Fine-scale population structure in a deep-sea teleost (orange roughy, Hoplostethus atlanticus)

    NASA Astrophysics Data System (ADS)

    Carlsson, Jens; Shephard, Samuel; Coughlan, James; Trueman, Clive N.; Rogan, Emer; Cross, Tom F.

    2011-06-01

    Microsatellite and otolith chemistry variability were analysed to assess fine scale genetic structure in the deep-sea teleost orange roughy ( Hoplostethus atlanticus). The Porcupine Bank located on the continental shelf west of Ireland, comprises a complex system of mounds and flat areas that are broken up by canyons. Orange roughy form spawning aggregations on mounds and flat areas, and were heavily fished until the resource was depleted. By analysing adults in spawning condition and juvenile orange roughy from six mounds and one flat area, shallow but significant genetic population structure was evident ( FST=0.0031, Dest across loci=0.0306 and G-test). Most of the structure was accounted for by inclusion of a sample from the flats (six of ten significant pairwise FST estimates and G-tests, and five of the highest Dest estimates included the flat sample). While the flat sample contributed most to the genetic structure, there was still significant (albeit weaker) structure among mound samples. The observed structure was supported by otolith analyses. Fish caught as late juveniles in either the flat or mound areas showed consistent differences in chemistry at the otolith core throughout the initial 10 years of growth, which could indicate site fidelity. We hypothesise that seafloor topographic structures (mounds and flats) may provide discrete spawning areas for orange roughy and that the limited gene flow between these spawning areas is insufficient to counteract genetic drift.

  1. Passive acoustic methods for fine-scale tracking of harbour porpoises in tidal rapids.

    PubMed

    Macaulay, Jamie; Gordon, Jonathan; Gillespie, Douglas; Malinka, Chloë; Northridge, Simon

    2017-02-01

    The growing interest in generating electrical power from tidal currents using tidal turbine generators raises a number of environmental concerns, including the risk that marine mammals might be injured or killed through collision with rotating turbine blades. To understand this risk, information on how marine mammals use tidal rapid habitats and in particular, their underwater movements and dive behaviour is required. Porpoises, which are the most abundant small cetacean at most European tidal sites, are difficult animals to tag, and the limited size of tidal habitats means that any telemetered animal would be likely to spend only a small proportion of time within them. Here, an alternative approach is explored, whereby passive acoustic monitoring (PAM) is used to obtain fine scale geo-referenced tracks of harbour porpoises in tidal rapid areas. Large aperture hydrophone arrays are required to obtain accurate locations of animals from PAM data and automated algorithms are necessary to process the large quantities of acoustic data collected on such systems during a typical survey. Methods to automate localisation, including a method to match porpoise detections on different hydrophones and separate different vocalising animals, and an assessment of the localisation accuracy of the large aperture hydrophone array are presented.

  2. Reduced fine-scale spatial genetic structure in grazed populations of Dianthus carthusianorum.

    PubMed

    Rico, Y; Wagner, H H

    2016-11-01

    Strong spatial genetic structure in plant populations can increase homozygosity, reducing genetic diversity and adaptive potential. The strength of spatial genetic structure largely depends on rates of seed dispersal and pollen flow. Seeds without dispersal adaptations are likely to be dispersed over short distances within the vicinity of the mother plant, resulting in spatial clustering of related genotypes (fine-scale spatial genetic structure, hereafter spatial genetic structure (SGS)). However, primary seed dispersal by zoochory can promote effective dispersal, increasing the mixing of seeds and influencing SGS within plant populations. In this study, we investigated the effects of seed dispersal by rotational sheep grazing on the strength of SGS and genetic diversity using 11 nuclear microsatellites for 49 populations of the calcareous grassland forb Dianthus carthusianorum. Populations connected by rotational sheep grazing showed significantly weaker SGS and higher genetic diversity than populations in ungrazed grasslands. Independent of grazing treatment, small populations showed significantly stronger SGS and lower genetic diversity than larger populations, likely due to genetic drift. A lack of significant differences in the strength of SGS and genetic diversity between populations that were recently colonized and pre-existing populations suggested that populations colonized after the reintroduction of rotational sheep grazing were likely founded by colonists from diverse source populations. We conclude that dispersal by rotational sheep grazing has the potential to considerably reduce SGS within D. carthusianorum populations. Our study highlights the effectiveness of landscape management by rotational sheep grazing to importantly reduce genetic structure at local scales within restored plant populations.

  3. Population density and sex do not influence fine-scale natal dispersal in roe deer.

    PubMed

    Gaillard, J-M; Hewison, A J M; Kjellander, P; Pettorelli, N; Bonenfant, C; Van Moorter, B; Liberg, O; Andren, H; Van Laere, G; Klein, F; Angibault, J-M; Coulon, A; Vanpé, C

    2008-09-07

    It is commonly assumed that the propensity to disperse and the dispersal distance of mammals should increase with increasing density and be greater among males than among females. However, most empirical evidence, especially on large mammals, has focused on highly polygynous and dimorphic species displaying female-defence mating tactics. We tested these predictions on roe deer, a weakly polygynous species of large herbivore exhibiting a resource-defence mating tactic at a fine spatial scale. Using three long-term studies of populations that were subject to the experimental manipulation of size, we did not find any support for either prediction, whether in terms of dispersal probability or dispersal distance. Our findings of similar dispersal patterns in both sexes of roe deer suggest that the underlying cause of natal dispersal is not related to inbreeding avoidance in this species. The absence of positive density dependence in fine-scale dispersal behaviour suggests that roe deer natal dispersal is a pre-saturation process that is shaped by heterogeneities in habitat quality rather than by density per se.

  4. A Genome-Wide, Fine-Scale Map of Natural Pigmentation Variation in Drosophila melanogaster

    PubMed Central

    Nolte, Viola; Tobler, Raymond; Stöbe, Petra; Futschik, Andreas; Schlötterer, Christian

    2013-01-01

    Various approaches can be applied to uncover the genetic basis of natural phenotypic variation, each with their specific strengths and limitations. Here, we use a replicated genome-wide association approach (Pool-GWAS) to fine-scale map genomic regions contributing to natural variation in female abdominal pigmentation in Drosophila melanogaster, a trait that is highly variable in natural populations and highly heritable in the laboratory. We examined abdominal pigmentation phenotypes in approximately 8000 female European D. melanogaster, isolating 1000 individuals with extreme phenotypes. We then used whole-genome Illumina sequencing to identify single nucleotide polymorphisms (SNPs) segregating in our sample, and tested these for associations with pigmentation by contrasting allele frequencies between replicate pools of light and dark individuals. We identify two small regions near the pigmentation genes tan and bric-à-brac 1, both corresponding to known cis-regulatory regions, which contain SNPs showing significant associations with pigmentation variation. While the Pool-GWAS approach suffers some limitations, its cost advantage facilitates replication and it can be applied to any non-model system with an available reference genome. PMID:23754958

  5. Fine-Scale Human Population Structure in Southern Africa Reflects Ecogeographic Boundaries

    PubMed Central

    Uren, Caitlin; Kim, Minju; Martin, Alicia R.; Bobo, Dean; Gignoux, Christopher R.; van Helden, Paul D.; Möller, Marlo; Hoal, Eileen G.; Henn, Brenna M.

    2016-01-01

    Recent genetic studies have established that the KhoeSan populations of southern Africa are distinct from all other African populations and have remained largely isolated during human prehistory until ∼2000 years ago. Dozens of different KhoeSan groups exist, belonging to three different language families, but very little is known about their population history. We examine new genome-wide polymorphism data and whole mitochondrial genomes for >100 South Africans from the ≠Khomani San and Nama populations of the Northern Cape, analyzed in conjunction with 19 additional southern African populations. Our analyses reveal fine-scale population structure in and around the Kalahari Desert. Surprisingly, this structure does not always correspond to linguistic or subsistence categories as previously suggested, but rather reflects the role of geographic barriers and the ecology of the greater Kalahari Basin. Regardless of subsistence strategy, the indigenous Khoe-speaking Nama pastoralists and the N|u-speaking ≠Khomani (formerly hunter-gatherers) share ancestry with other Khoe-speaking forager populations that form a rim around the Kalahari Desert. We reconstruct earlier migration patterns and estimate that the southern Kalahari populations were among the last to experience gene flow from Bantu speakers, ∼14 generations ago. We conclude that local adoption of pastoralism, at least by the Nama, appears to have been primarily a cultural process with limited genetic impact from eastern Africa. PMID:27474727

  6. Inter-annual maintenance of the fine-scale genetic structure in a biennial plant

    PubMed Central

    Valverde, Javier; Gómez, José María; García, Cristina; Sharbel, Timothy F.; Jiménez, María Noelia; Perfectti, Francisco

    2016-01-01

    Within plant populations, space-restricted gene movement, together with environmental heterogeneity, can result in a spatial variation in gene frequencies. In biennial plants, inter-annual flowering migrants can homogenize gene frequencies between consecutive cohorts. However, the actual impact of these migrants on spatial genetic variation remains unexplored. Here, we used 10 nuclear microsatellite and one plastid genetic marker to characterize the spatial genetic structure within two consecutive cohorts in a population of the biennial plant Erysimum mediohispanicum (Brassicaceae). We explored the maintenance of this structure between consecutive flowering cohorts at different levels of complexity, and investigated landscape effects on gene flow. We found that cohorts were not genetically differentiated and showed a spatial genetic structure defined by a negative genetic-spatial correlation at fine scale that varied in intensity with compass directions. This spatial genetic structure was maintained when comparing plants from different cohorts. Additionally, genotypes were consistently associated with environmental factors such as light availability and soil composition, but to a lesser extent compared with the spatial autocorrelation. We conclude that inter-annual migrants, in combination with limited seed dispersal and environmental heterogeneity, play a major role in shaping and maintaining the spatial genetic structure among cohorts in this biennial plant. PMID:27883087

  7. Fine-scale behavioural differences distinguish resource use by ecomorphs in a closed ecosystem

    PubMed Central

    Hawley, Kate L.; Rosten, Carolyn M.; Christensen, Guttorm; Lucas, Martyn C.

    2016-01-01

    Temporal differences in habitat use and foraging specialisms between ecomorphs represent aspects of behavioural phenotype that are poorly understood with regard to the origin and maintenance of ecological diversity. We tested the role of behaviour in resource use divergence of two Arctic charr (Salvelinus alpinus) phenotypes, a slim, putatively pelagic-dwelling morph and a robust, putatively littoral-dwelling generalist morph, over an annual cycle, using biotelemetry and stable isotopes. Pelagic morph charr exhibited significantly greater δC13 depletion, concordant with increased zooplanktivory, than for the Littoral morph. Although three-dimensional space-use of the morphs strongly overlapped, on average, the Littoral morph used that habitat 19.3% more than the Pelagic morph. Pelagic morph fish were significantly more active, further from the lake bed and at greater depth than Littoral fish (annual means respectively, Pelagic, 0.069BLs−1, 8.21 m and 14.11 m; Littoral, 0.047BLs−1, 5.87 m and 10.47 m). Patterns of habitat use differed between ecomorphs at key times, such as during autumn and at ice break, likely related to spawning and resumption of intensive foraging respectively. Extensive space-use overlap, but fine-scale differences in habitat use between charr ecomorphs, suggests the importance of competition for generating and maintaining polymorphism, and its potential for promoting reproductive isolation and evolution in sympatry. PMID:27098197

  8. Relative influence upon microwave emissivity of fine-scale stratigraphy, internal scattering, and dielectric properties

    USGS Publications Warehouse

    England, A.W.

    1976-01-01

    The microwave emissivity of relatively low-loss media such as snow, ice, frozen ground, and lunar soil is strongly influenced by fine-scale layering and by internal scattering. Radiometric data, however, are commonly interpreted using a model of emission from a homogeneous, dielectric halfspace whose emissivity derives exclusively from dielectric properties. Conclusions based upon these simple interpretations can be erroneous. Examples are presented showing that the emission from fresh or hardpacked snow over either frozen or moist soil is governed dominantly by the size distribution of ice grains in the snowpack. Similarly, the thickness of seasonally frozen soil and the concentration of rock clasts in lunar soil noticeably affect, respectively, the emissivities of northern latitude soils in winter and of the lunar regolith. Petrophysical data accumulated in support of the geophysical interpretation of microwave data must include measurements of not only dielectric properties, but also of geometric factors such as finescale layering and size distributions of grains, inclusions, and voids. ?? 1976 Birkha??user Verlag.

  9. Fine-scale genetic differentiation of a temperate herb: relevance of local environments and demographic change

    PubMed Central

    Sato, Yasuhiro; Kudoh, Hiroshi

    2014-01-01

    The genetic structure of a plant species is shaped by environmental adaptation and demographic factors, but their relative contributions are still unknown. To examine the environment- or geography-related differentiation, we quantified genetic variation among 41 populations of a temperate herb, Arabidopsis halleri subsp. gemmifera (Brassicaceae). We analysed 19 microsatellite loci, which showed a significant population differentiation and a moderate within-population genetic diversity (global Gst = 0.42 and Hs = 0.19). Our structure analysis and phylogenetic network did not detect more than two genetic groups across the Japanese mainland but found fine-scale genetic differentiations and admixed patterns around the central area. Across the Japanese mainland, we found significant evidence for isolation-by-distance but not for isolation-by-environments. However, at least within the central area, the magnitude of genetic differentiation tended to increase with microhabitat dissimilarity under light conditions and water availability. Furthermore, most populations have been estimated to experience a recent decline in the effective population size, indicating a possibility of bottleneck effects on the pattern of genetic variation. These findings highlight a potential influence of the microhabitat conditions and demographic changes on the local-scale genetic differentiation among natural plant populations. PMID:25387749

  10. Fine-scale local adaptation in an invasive freshwater fish has evolved in contemporary time

    PubMed Central

    Westley, Peter A. H.; Ward, Eric J.; Fleming, Ian A.

    2013-01-01

    Adaptive evolutionary change in only a few generations can increase the ability of non-native invasive species to spread, and yet adaptive divergence is rarely assessed in recently established populations. In this study, we experimentally test for evidence of fine-scale local adaptation in juvenile survival and growth among three populations of an invasive freshwater fish with reciprocal transplants and common-garden experiments. Despite intrinsic differences in habitat quality, in two of three populations we detected evidence of increased survival in ‘home’ versus ‘away’ environments with a Bayesian occupancy model fitted to mark–recapture data. We found support for the ‘local’ versus ‘foreign’ criterion of local adaptation as 14 of 15 pairwise comparisons of performance were consistent with local adaptation (p < 0.001). Patterns in growth were less clear, though we detected evidence of location- and population-level effects. Although the agents of divergent ecological selection are not known in this system, our results combine to indicate that adaptive divergence—reflected by higher relative survival of local individuals—can occur in a small number of generations and only a few kilometres apart on the landscape. PMID:23193126

  11. Fabrication of 3D fine scale PZT components by ink-jet prototyping process

    NASA Astrophysics Data System (ADS)

    Noguera, R.; Dossou-Yovo, C.; Lejeune, M.; Chartier, T.

    2005-09-01

    Different investigations have been carried out to optimize an ink-jet printing technique, devoted to the fabrication of 3D fine scale PZT parts, by adjustment of the fluid properties of the ceramic suspensions and by controlling the ejection and impact phenomena. A 10 vol% PZT loaded suspension characterized by a Newtonian behavior, corresponding to a viscosity of 10mPa.s and to a ratio Re/We1/2 of 5.98 has been selected. The ejection and impact phenomena strongly depend on the driving parameters of the printing head, in particular the formation of the droplet, with satellite or not, as well as its velocity and volume which are function of the pulse amplitude. Moreover, the conditions of ejection (droplet velocity and volume) control the characteristics of the deposit (definition, spreading, thickness uniformity). Sintered PZT pillar array has been achieved by ink-jet printing with a definition equal to 50μm. These structures could be very useful to improve the performances of 1-3 ceramic polymer composites for imaging probes or more generally for ultrasonic transducers and also of micro-deformable mirrors for optical adaptive systems.

  12. Fine scale mapping of the structure and composition of the Elkhorn Slough (California, USA) tidal plume

    NASA Astrophysics Data System (ADS)

    Fischer, Andrew M.; Ryan, John P.; Rienecker, Erich V.

    2017-01-01

    Fine scale mapping of the structure and composition of a tidal ebb plume from a highly modified coastal lagoon (Elkhorn Slough, California, USA) was conducted by combining in situ, observational data sets from surface underway mapping, autonomous underwater vehicle (AUV) profiles, drifter tracking and the analysis of plume structure indices. The results reveal a 6-m-deep, jet-like, sediment laden plume extending one km offshore at low tide, which becomes entrained in the prevailing nearshore circulation. The plume that exits the slough is significantly different from the water that enters the slough. The rapidly evolving discharge plume is associated with elevated and highly correlated (r = 0.93) concentrations of dissolved organic matter and nitrate. While dissolved constituents remain in the shallow plume and are transported northward with the prevailing current, sediment may settle quickly through the water column and can be transported southwestward with the littoral currents. This study illustrates the applications of AUVs, when coupled with additional datasets, for generating higher resolution observational snapshots of dynamic and ephemeral tidal plumes. The results provide unique perspective on small-scale dynamics of an estuarine plume and its influence on coastal ecology.

  13. Dynamics of land change in India: a fine-scale spatial analysis

    NASA Astrophysics Data System (ADS)

    Meiyappan, P.; Roy, P. S.; Sharma, Y.; Jain, A. K.; Ramachandran, R.; Joshi, P. K.

    2015-12-01

    Land is scarce in India: India occupies 2.4% of worlds land area, but supports over 1/6th of worlds human and livestock population. This high population to land ratio, combined with socioeconomic development and increasing consumption has placed tremendous pressure on India's land resources for food, feed, and fuel. In this talk, we present contemporary (1985 to 2005) spatial estimates of land change in India using national-level analysis of Landsat imageries. Further, we investigate the causes of the spatial patterns of change using two complementary lines of evidence. First, we use statistical models estimated at macro-scale to understand the spatial relationships between land change patterns and their concomitant drivers. This analysis using our newly compiled extensive socioeconomic database at village level (~630,000 units), is 100x higher in spatial resolution compared to existing datasets, and covers over 200 variables. The detailed socioeconomic data enabled the fine-scale spatial analysis with Landsat data. Second, we synthesized information from over 130 survey based case studies on land use drivers in India to complement our macro-scale analysis. The case studies are especially useful to identify unobserved variables (e.g. farmer's attitude towards risk). Ours is the most detailed analysis of contemporary land change in India, both in terms of national extent, and the use of detailed spatial information on land change, socioeconomic factors, and synthesis of case studies.

  14. Fine-scale genetic structure of Nothofagus pumilio (lenga) at contrasting elevations of the altitudinal gradient.

    PubMed

    Mathiasen, Paula; Premoli, Andrea C

    2013-03-01

    Montane forests provide the natural framework to test for various ecological settings at distinct elevations as they may affect population demography, which in turn will affect the spatial genetic structure (SGS). We analyzed the fine-scale SGS of Nothofagus pumilio, which dominates mountain areas of Patagonia, in three pairs of sites at contrasting elevations (low- vs. high-elevation). Within a total area of 1 ha fresh leaf tissue from 90 individuals was collected at each of the six studied stands following a spatially explicit sampling design. Population genetic diversity parameters were analyzed for all sampled individuals using five polymorphic isozyme loci, and a subset of 50 individuals per stand were also screened for five microsatellite loci. The SGS was assessed on 50 individuals/stand, using the combined datasets of isozymes and microsatellites. Most low-elevation stands consisted of older individuals with complex age structures and genetically diverse plots. In contrast, high-elevation stands and one post-fire low-elevation population yielded even-aged structures with evidence of growth suppression, and were genetically homogeneous. All stands yielded significant SGS. Similarly to mature stands of the non-sprouter congener Nothofagus dombeyi, multi-age low-altitude N. pumilio yielded significant SGS weakened by competing species of the understory and the formation of seedling banks. Alike the sprouter Nothofagus antarctica, high-altitude stands produced significant SGS as a consequence of occasional seedling establishment reinforced by vegetative spread.

  15. Inter-annual maintenance of the fine-scale genetic structure in a biennial plant.

    PubMed

    Valverde, Javier; Gómez, José María; García, Cristina; Sharbel, Timothy F; Jiménez, María Noelia; Perfectti, Francisco

    2016-11-24

    Within plant populations, space-restricted gene movement, together with environmental heterogeneity, can result in a spatial variation in gene frequencies. In biennial plants, inter-annual flowering migrants can homogenize gene frequencies between consecutive cohorts. However, the actual impact of these migrants on spatial genetic variation remains unexplored. Here, we used 10 nuclear microsatellite and one plastid genetic marker to characterize the spatial genetic structure within two consecutive cohorts in a population of the biennial plant Erysimum mediohispanicum (Brassicaceae). We explored the maintenance of this structure between consecutive flowering cohorts at different levels of complexity, and investigated landscape effects on gene flow. We found that cohorts were not genetically differentiated and showed a spatial genetic structure defined by a negative genetic-spatial correlation at fine scale that varied in intensity with compass directions. This spatial genetic structure was maintained when comparing plants from different cohorts. Additionally, genotypes were consistently associated with environmental factors such as light availability and soil composition, but to a lesser extent compared with the spatial autocorrelation. We conclude that inter-annual migrants, in combination with limited seed dispersal and environmental heterogeneity, play a major role in shaping and maintaining the spatial genetic structure among cohorts in this biennial plant.

  16. Fine scale mapping of the breast cancer 16q12 locus

    PubMed Central

    Udler, Miriam S.; Ahmed, Shahana; Healey, Catherine S.; Meyer, Kerstin; Struewing, Jeffrey; Maranian, Melanie; Kwon, Erika M.; Zhang, Jinghui; Tyrer, Jonathan; Karlins, Eric; Platte, Radka; Kalmyrzaev, Bolot; Dicks, Ed; Field, Helen; Maia, Ana-Teresa; Prathalingam, Radhika; Teschendorff, Andrew; McArthur, Stewart; Doody, David R.; Luben, Robert; Caldas, Carlos; Bernstein, Leslie; Kolonel, Laurence K.; Henderson, Brian E.; Wu, Anna H.; Le Marchand, Loic; Ursin, Giske; Press, Michael F.; Lindblom, Annika; Margolin, Sara; Shen, Chen-Yang; Yang, Show-Lin; Hsiung, Chia-Ni; Kang, Daehee; Yoo, Keun-Young; Noh, Dong-Young; Ahn, Sei-Hyun; Malone, Kathleen E.; Haiman, Christopher A.; Pharoah, Paul D.; Ponder, Bruce A.J.; Ostrander, Elaine A.; Easton, Douglas F.; Dunning, Alison M.

    2010-01-01

    Recent genome-wide association studies have identified a breast cancer susceptibility locus on 16q12 with an unknown biological basis. We used a set of single nucleotide polymorphism (SNP) markers to generate a fine-scale map and narrowed the region of association to a 133 kb DNA segment containing the largely uncharacterized hypothetical gene LOC643714, a short intergenic region and the 5′ end of TOX3. Re-sequencing this segment in European subjects identified 293 common polymorphisms, including a set of 26 highly correlated candidate causal variants. By evaluation of these SNPs in five breast cancer case–control studies involving more than 23 000 subjects from populations of European and Southeast Asian ancestry, all but 14 variants could be excluded at odds of <1:100. Most of the remaining variants lie in the intergenic region, which exhibits evolutionary conservation and open chromatin conformation, consistent with a regulatory function. African-American case–control studies exhibit a different pattern of association suggestive of an additional causative variant. PMID:20332101

  17. Does temperature affect the accuracy of vented pressure transducer in fine-scale water level measurement?

    NASA Astrophysics Data System (ADS)

    Liu, Z.; Higgins, C. W.

    2015-03-01

    Submersible pressure transducers have been utilized for collecting water level data since the early 1960s. Together with a digital data logger, it is a convenient way to record water level fluctuations for long-term monitoring. Despite the wide use of pressure transducers for water level monitoring, little has been reported regarding their accuracy and performance under field conditions. The effects of temperature fluctuations on the output of vented pressure transducers were considered in this study. The pressure transducers were tested under both laboratory and field conditions. The results of this study indicate that temperature fluctuation has a strong effect on the transducer output. Rapid changes in temperature introduce noise and fluctuations in the water level readings under a constant hydraulic head while the absolute temperature is also related to sensor errors. The former is attributed to venting and the latter is attributed to temperature compensation effects in the strain gauges. Individual pressure transducers responded differently to the thermal fluctuations in the same testing environment. In the field of surface hydrology, especially when monitoring fine-scale water level fluctuations, ignoring or failing to compensate for the temperature effect can introduce considerable error into pressure transducer readings. It is recommended that a performance test for the pressure transducer is conducted before field deployment.

  18. Unexpected fine-scale population structure in a broadcast-spawning Antarctic marine mollusc.

    PubMed

    Hoffman, Joseph I; Clarke, Andy; Clark, Melody S; Fretwell, Peter; Peck, Lloyd S

    2012-01-01

    Several recent empirical studies have challenged the prevailing dogma that broadcast-spawning species exhibit little or no population genetic structure by documenting genetic discontinuities associated with large-scale oceanographic features. However, relatively few studies have explored patterns of genetic differentiation over fine spatial scales. Consequently, we used a hierarchical sampling design to investigate the basis of a weak but significant genetic difference previously reported between Antarctic limpets (Nacella concinna) sampled from Adelaide and Galindez Islands near the base of the Antarctic Peninsula. Three sites within Ryder Bay, Adelaide Island (Rothera Point, Leonie and Anchorage Islands) were each sub-sampled three times, yielding a total of 405 samples that were genotyped at 155 informative Amplified Fragment Length Polymorphisms (AFLPs). Contrary to our initial expectations, limpets from Anchorage Island were found to be subtly, but significantly distinct from those sampled from the other sites. This suggests that local processes may play an important role in generating fine-scale population structure even in species with excellent dispersal capabilities, and highlights the importance of sampling at multiple spatial scales in population genetic surveys.

  19. A nanobuffer reporter library for fine-scale imaging and perturbation of endocytic organelles

    PubMed Central

    Wang, Chensu; Wang, Yiguang; Li, Yang; Bodemann, Brian; Zhao, Tian; Ma, Xinpeng; Huang, Gang; Hu, Zeping; DeBerardinis, Ralph J.; White, Michael A.; Gao, Jinming

    2015-01-01

    Endosomes, lysosomes and related catabolic organelles are a dynamic continuum of vacuolar structures that impact a number of cell physiological processes such as protein/lipid metabolism, nutrient sensing and cell survival. Here we develop a library of ultra-pH-sensitive fluorescent nanoparticles with chemical properties that allow fine-scale, multiplexed, spatio-temporal perturbation and quantification of catabolic organelle maturation at single organelle resolution to support quantitative investigation of these processes in living cells. Deployment in cells allows quantification of the proton accumulation rate in endosomes; illumination of previously unrecognized regulatory mechanisms coupling pH transitions to endosomal coat protein exchange; discovery of distinct pH thresholds required for mTORC1 activation by free amino acids versus proteins; broad-scale characterization of the consequence of endosomal pH transitions on cellular metabolomic profiles; and functionalization of a context-specific metabolic vulnerability in lung cancer cells. Together, these biological applications indicate the robustness and adaptability of this nanotechnology-enabled ‘detection and perturbation' strategy. PMID:26437053

  20. Restricted gene flow and fine-scale population structuring in tool using New Caledonian crows.

    PubMed

    Rutz, C; Ryder, T B; Fleischer, R C

    2012-04-01

    New Caledonian crows Corvus moneduloides are the most prolific avian tool users. It has been suggested that some aspects of their complex tool use behaviour are under the influence of cultural processes, involving the social transmission-and perhaps even progressive refinement-of tool designs. Using microsatellite and mt-haplotype profiling of crows from three distinct habitats (dry forest, farmland and beachside habitat), we show that New Caledonian crow populations can exhibit significant fine-scale genetic structuring. Our finding that some sites of <10 km apart were highly differentiated demonstrates considerable potential for genetic and/or cultural isolation of crow groups. Restricted movement of birds between local populations at such small spatial scales, especially across habitat boundaries, illustrates how specific tool designs could be preserved over time, and how tool technologies of different crow groups could diverge due to drift and local selection pressures. Young New Caledonian crows have an unusually long juvenile dependency period, during which they acquire complex tool-related foraging skills. We suggest that the resulting delayed natal dispersal drives population-divergence patterns in this species. Our work provides essential context for future studies that examine the genetic makeup of crow populations across larger geographic areas, including localities with suspected cultural differences in crow tool technologies.

  1. Fine-scale urbanization affects Odonata species diversity in ponds of a megacity (Paris, France)

    NASA Astrophysics Data System (ADS)

    Jeanmougin, Martin; Leprieur, Fabien; Loïs, Grégoire; Clergeau, Philippe

    2014-08-01

    Current developments in urban ecology include very few studies focused on pond ecosystems, though ponds are recognized as biodiversity hotspots. Using Odonata as an indicator model, we explored changes in species composition in ponds localized along an urban gradient of a megacity (Paris, France). We then assessed the relative importance of local- and landscape-scale variables in shaping Odonata α-diversity patterns using a model-averaging approach. Analyses were performed for adult (A) and adult plus exuviae (AE) census data. At 26 ponds, we recorded 657 adults and 815 exuviae belonging to 17 Odonata species. The results showed that the Odonata species assemblage composition was not determined by pond localization along the urban gradient. Similarly, pond characteristics were found to be similar among urban, suburban and periurban ponds. The analyses of AE census data revealed that fine-scale urbanization (i.e., increased density of buildings surrounding ponds) negatively affects Odonata α-diversity. In contrast, pond localization along the urban gradient weakly explained the α-diversity patterns. Several local-scale variables, such as the coverage of submerged macrophytes, were found to be significant drivers of Odonata α-diversity. Together, these results show that the degree of urbanization around ponds must be considered instead of pond localization along the urban gradient when assessing the potential impacts of urbanization on Odonata species diversity. This work also indicates the importance of exuviae sampling in understanding the response of Odonata to urbanization.

  2. Genomic valorization of the fine scale classification of small millet landraces in southern India.

    PubMed

    Newmaster, Steven G; Ragupathy, Subramanyam; Dhivya, Shanmughanandhan; Jijo, Chitilappilly Joseph; Sathishkumar, Ramalingam; Patel, Kirit

    2013-02-01

    Our research seeks to investigate genomic diversity of landraces of millet, addressing a key uncertainty that will provide a framework for (i) a DNA barcode method that could be used for fast, sensitive, and accurate identification of millet landraces, and (ii) millet landrace conservation including biocultural diversity. We found considerable intraspecific variation among 15 landraces representing six species of small millets using nuclear regions (ITS, ITS1, and ITS2); there was no variation in plastid regions (rbcL, matK, and trnH-psbA). An efficacious ITS2 DNA barcode was used to make 100% accurate landrace assignments for 150 blind samples representing 15 landraces. Our research revealed that genomic variation is aligned with a fine-scale classification of landraces using traditional knowledge (TK) of local farmers. The landrace classification was highly correlated with traits (morphological, agricultural, and cultural utility) associated with considerable factors such as yield, drought tolerance, growing season, medicinal properties, and nutrition. This could provide a DNA-based model for conservation of genetic diversity and the associated bicultural diversity (TK) of millet landraces, which has sustained marginal farming communities in harsh environments for many generations.

  3. Regulation of the demographic structure in isomorphic biphasic life cycles at the spatial fine scale.

    PubMed

    Vieira, Vasco Manuel Nobre de Carvalho da Silva; Mateus, Marcos Duarte

    2014-01-01

    Isomorphic biphasic algal life cycles often occur in the environment at ploidy abundance ratios (Haploid:Diploid) different from 1. Its spatial variability occurs within populations related to intertidal height and hydrodynamic stress, possibly reflecting the niche partitioning driven by their diverging adaptation to the environment argued necessary for their prevalence (evolutionary stability). Demographic models based in matrix algebra were developed to investigate which vital rates may efficiently generate an H:D variability at a fine spatial resolution. It was also taken into account time variation and type of life strategy. Ploidy dissimilarities in fecundity rates set an H:D spatial structure miss-fitting the ploidy fitness ratio. The same happened with ploidy dissimilarities in ramet growth whenever reproductive output dominated the population demography. Only through ploidy dissimilarities in looping rates (stasis, breakage and clonal growth) did the life cycle respond to a spatially heterogeneous environment efficiently creating a niche partition. Marginal locations were more sensitive than central locations. Related results have been obtained experimentally and numerically for widely different life cycles from the plant and animal kingdoms. Spore dispersal smoothed the effects of ploidy dissimilarities in fertility and enhanced the effects of ploidy dissimilarities looping rates. Ploidy dissimilarities in spore dispersal could also create the necessary niche partition, both over the space and time dimensions, even in spatial homogeneous environments and without the need for conditional differentiation of the ramets. Fine scale spatial variability may be the key for the prevalence of isomorphic biphasic life cycles, which has been neglected so far.

  4. Fine-Scale Zonal Flow Suppression of Electron Temperature Gradient Turbulence

    SciTech Connect

    Parker, S. E.; Kohut, J. J.; Chen, Y.; Lin, Z.; Hinton, F. L.; Lee, W. W.

    2006-11-30

    It is found in collisionless Electron Temperature Gradient (ETG) turbulence simulations that, while zonal flows are weak at early times, the zonal flows continue to grow algebraically (proportional to time). These fine-scale zonal flows have a radial wave number such that kr{rho}i > 1 and kr{rho}e < 1. Eventually, the zonal flows grow to a level that suppresses the turbulence due to ExB shearing. The final electron energy flux is found to be relatively low. These conclusions are based on particle convergence studies with adiabatic ion electrostatic flux-tube gyrokinetic {delta}f particle simulations run for long times. The Rosenbluth-Hinton random walk mechanism is given as an explanation for the long time build up of the zonal flow in ETG turbulence and it is shown that the generation is (k perpendicular {rho}e)2 smaller than for isomorphic Ion Temperature Gradient (ITG) problem. This mechanism for zonal flow generation here is different than the modulational instability mechanism for ITG turbulence. These results are important because previous results indicated zonal flows were unimportant for ETG turbulence. Weak collisional damping of the zonal flow is also shown to be a n important effect.

  5. Fine-scale patterns of population stratification confound rare variant association tests.

    PubMed

    O'Connor, Timothy D; Kiezun, Adam; Bamshad, Michael; Rich, Stephen S; Smith, Joshua D; Turner, Emily; Leal, Suzanne M; Akey, Joshua M

    2013-01-01

    Advances in next-generation sequencing technology have enabled systematic exploration of the contribution of rare variation to Mendelian and complex diseases. Although it is well known that population stratification can generate spurious associations with common alleles, its impact on rare variant association methods remains poorly understood. Here, we performed exhaustive coalescent simulations with demographic parameters calibrated from exome sequence data to evaluate the performance of nine rare variant association methods in the presence of fine-scale population structure. We find that all methods have an inflated spurious association rate for parameter values that are consistent with levels of differentiation typical of European populations. For example, at a nominal significance level of 5%, some test statistics have a spurious association rate as high as 40%. Finally, we empirically assess the impact of population stratification in a large data set of 4,298 European American exomes. Our results have important implications for the design, analysis, and interpretation of rare variant genome-wide association studies.

  6. Limited Dispersal and Significant Fine - Scale Genetic Structure in a Tropical Montane Parrot Species.

    PubMed

    Klauke, Nadine; Schaefer, H Martin; Bauer, Michael; Segelbacher, Gernot

    2016-01-01

    Tropical montane ecosystems are biodiversity hotspots harbouring many endemics that are confined to specific habitat types within narrow altitudinal ranges. While deforestation put these ecosystems under threat, we still lack knowledge about how heterogeneous environments like the montane tropics promote population connectivity and persistence. We investigated the fine-scale genetic structure of the two largest subpopulations of the endangered El Oro parakeet (Pyrrhura orcesi) endemic to the Ecuadorian Andes. Specifically, we assessed the genetic divergence between three sites separated by small geographic distances but characterized by a heterogeneous habitat structure. Although geographical distances between sites are small (3-17 km), we found genetic differentiation between all sites. Even though dispersal capacity is generally high in parrots, our findings indicate that dispersal is limited even on this small geographic scale. Individual genotype assignment revealed similar genetic divergence across a valley (~ 3 km distance) compared to a continuous mountain range (~ 13 km distance). Our findings suggest that geographic barriers promote genetic divergence even on small spatial scales in this endangered endemic species. These results may have important implications for many other threatened and endemic species, particularly given the upslope shift of species predicted from climate change.

  7. Fine scale endemism on coral reefs: archipelagic differentiation in turbinid gastropods.

    PubMed

    Meyer, Christopher P; Geller, Jonathan B; Paulay, Gustav

    2005-01-01

    The perceived wide geographic range of organisms in the sea, facilitated by ready dispersal of waterborne dispersal stages, is a challenge for hypotheses of marine speciation but a boon to efforts of marine conservation. Wide species ranges are especially striking in the reef-rich Indo-west Pacific, the largest and most diverse marine biogeographic region, extending across half the planet. The insular marine biota of the tropical Pacific is characterized by wide-ranging species and provides the most striking examples of long distance dispersal, with endemism largely confined to the most remote island groups. Here we show that the gastropod Astralium "rhodostomum" has developed endemic clades on almost every Pacific archipelago sampled, a pattern unprecedented in marine biogeography, and reminiscent of the terrestrial biota of oceanic islands. Mitochondrial DNA sequences indicate that this species-complex is comprised of at least 30 geographically isolated clades, separated by as little as 180 km. Evidence suggests that such fine scale endemism and high diversity is not exceptional, but likely characterizes a substantial fraction of the reef biota. These results imply that (1) marine speciation can regularly occur over much finer spatial scales than generally accepted, (2) the diversity of coral reefs is even higher than suggested by morphology-based estimates, and (3) conservation efforts need to focus at the archipelagic level in the sea as on land.

  8. Fine-Scale Survey of X Chromosome Copy Number Variants and Indels Underlying Intellectual Disability

    PubMed Central

    Whibley, Annabel C.; Plagnol, Vincent; Tarpey, Patrick S.; Abidi, Fatima; Fullston, Tod; Choma, Maja K.; Boucher, Catherine A.; Shepherd, Lorraine; Willatt, Lionel; Parkin, Georgina; Smith, Raffaella; Futreal, P. Andrew; Shaw, Marie; Boyle, Jackie; Licata, Andrea; Skinner, Cindy; Stevenson, Roger E.; Turner, Gillian; Field, Michael; Hackett, Anna; Schwartz, Charles E.; Gecz, Jozef; Stratton, Michael R.; Raymond, F. Lucy

    2010-01-01

    Copy number variants and indels in 251 families with evidence of X-linked intellectual disability (XLID) were investigated by array comparative genomic hybridization on a high-density oligonucleotide X chromosome array platform. We identified pathogenic copy number variants in 10% of families, with mutations ranging from 2 kb to 11 Mb in size. The challenge of assessing causality was facilitated by prior knowledge of XLID-associated genes and the ability to test for cosegregation of variants with disease through extended pedigrees. Fine-scale analysis of rare variants in XLID families leads us to propose four additional genes, PTCHD1, WDR13, FAAH2, and GSPT2, as candidates for XLID causation and the identification of further deletions and duplications affecting X chromosome genes but without apparent disease consequences. Breakpoints of pathogenic variants were characterized to provide insight into the underlying mutational mechanisms and indicated a predominance of mitotic rather than meiotic events. By effectively bridging the gap between karyotype-level investigations and X chromosome exon resequencing, this study informs discussion of alternative mutational mechanisms, such as noncoding variants and non-X-linked disease, which might explain the shortfall of mutation yield in the well-characterized International Genetics of Learning Disability (IGOLD) cohort, where currently disease remains unexplained in two-thirds of families. PMID:20655035

  9. Fine-scale genetic correlates to condition and migration in a wild cervid

    PubMed Central

    Northrup, Joseph M; Shafer, Aaron B A; Anderson, Charles R; Coltman, David W; Wittemyer, George

    2014-01-01

    The relationship between genetic variation and phenotypic traits is fundamental to the study and management of natural populations. Such relationships often are investigated by assessing correlations between phenotypic traits and heterozygosity or genetic differentiation. Using an extensive data set compiled from free-ranging mule deer (Odocoileus hemionus), we combined genetic and ecological data to (i) examine correlations between genetic differentiation and migration timing, (ii) screen for mitochondrial haplotypes associated with migration timing, and (iii) test whether nuclear heterozygosity was associated with condition. Migration was related to genetic differentiation (more closely related individuals migrated closer in time) and mitochondrial haplogroup. Body fat was related to heterozygosity at two nuclear loci (with antagonistic patterns), one of which is situated near a known fat metabolism gene in mammals. Despite being focused on a widespread panmictic species, these findings revealed a link between genetic variation and important phenotypes at a fine scale. We hypothesize that these correlations are either the result of mixing refugial lineages or differential mitochondrial haplotypes influencing energetics. The maintenance of phenotypic diversity will be critical to enable the potential tracking of changing climatic conditions, and these correlates highlight the need to consider evolutionary mechanisms in management, even in widely distributed panmictic species. PMID:25469172

  10. Limited Dispersal and Significant Fine - Scale Genetic Structure in a Tropical Montane Parrot Species

    PubMed Central

    Klauke, Nadine; Schaefer, H. Martin; Bauer, Michael; Segelbacher, Gernot

    2016-01-01

    Tropical montane ecosystems are biodiversity hotspots harbouring many endemics that are confined to specific habitat types within narrow altitudinal ranges. While deforestation put these ecosystems under threat, we still lack knowledge about how heterogeneous environments like the montane tropics promote population connectivity and persistence. We investigated the fine-scale genetic structure of the two largest subpopulations of the endangered El Oro parakeet (Pyrrhura orcesi) endemic to the Ecuadorian Andes. Specifically, we assessed the genetic divergence between three sites separated by small geographic distances but characterized by a heterogeneous habitat structure. Although geographical distances between sites are small (3–17 km), we found genetic differentiation between all sites. Even though dispersal capacity is generally high in parrots, our findings indicate that dispersal is limited even on this small geographic scale. Individual genotype assignment revealed similar genetic divergence across a valley (~ 3 km distance) compared to a continuous mountain range (~ 13 km distance). Our findings suggest that geographic barriers promote genetic divergence even on small spatial scales in this endangered endemic species. These results may have important implications for many other threatened and endemic species, particularly given the upslope shift of species predicted from climate change. PMID:28033364

  11. Fine-Scale Human Population Structure in Southern Africa Reflects Ecogeographic Boundaries.

    PubMed

    Uren, Caitlin; Kim, Minju; Martin, Alicia R; Bobo, Dean; Gignoux, Christopher R; van Helden, Paul D; Möller, Marlo; Hoal, Eileen G; Henn, Brenna M

    2016-09-01

    Recent genetic studies have established that the KhoeSan populations of southern Africa are distinct from all other African populations and have remained largely isolated during human prehistory until ∼2000 years ago. Dozens of different KhoeSan groups exist, belonging to three different language families, but very little is known about their population history. We examine new genome-wide polymorphism data and whole mitochondrial genomes for >100 South Africans from the ≠Khomani San and Nama populations of the Northern Cape, analyzed in conjunction with 19 additional southern African populations. Our analyses reveal fine-scale population structure in and around the Kalahari Desert. Surprisingly, this structure does not always correspond to linguistic or subsistence categories as previously suggested, but rather reflects the role of geographic barriers and the ecology of the greater Kalahari Basin. Regardless of subsistence strategy, the indigenous Khoe-speaking Nama pastoralists and the N|u-speaking ≠Khomani (formerly hunter-gatherers) share ancestry with other Khoe-speaking forager populations that form a rim around the Kalahari Desert. We reconstruct earlier migration patterns and estimate that the southern Kalahari populations were among the last to experience gene flow from Bantu speakers, ∼14 generations ago. We conclude that local adoption of pastoralism, at least by the Nama, appears to have been primarily a cultural process with limited genetic impact from eastern Africa.

  12. Fine-scale behavioural differences distinguish resource use by ecomorphs in a closed ecosystem.

    PubMed

    Hawley, Kate L; Rosten, Carolyn M; Christensen, Guttorm; Lucas, Martyn C

    2016-04-21

    Temporal differences in habitat use and foraging specialisms between ecomorphs represent aspects of behavioural phenotype that are poorly understood with regard to the origin and maintenance of ecological diversity. We tested the role of behaviour in resource use divergence of two Arctic charr (Salvelinus alpinus) phenotypes, a slim, putatively pelagic-dwelling morph and a robust, putatively littoral-dwelling generalist morph, over an annual cycle, using biotelemetry and stable isotopes. Pelagic morph charr exhibited significantly greater δC(13) depletion, concordant with increased zooplanktivory, than for the Littoral morph. Although three-dimensional space-use of the morphs strongly overlapped, on average, the Littoral morph used that habitat 19.3% more than the Pelagic morph. Pelagic morph fish were significantly more active, further from the lake bed and at greater depth than Littoral fish (annual means respectively, Pelagic, 0.069 BL s(-1), 8.21 m and 14.11 m; Littoral, 0.047 BL s(-1), 5.87 m and 10.47 m). Patterns of habitat use differed between ecomorphs at key times, such as during autumn and at ice break, likely related to spawning and resumption of intensive foraging respectively. Extensive space-use overlap, but fine-scale differences in habitat use between charr ecomorphs, suggests the importance of competition for generating and maintaining polymorphism, and its potential for promoting reproductive isolation and evolution in sympatry.

  13. Mapping to Support Fine Scale Epidemiological Cholera Investigations: A Case Study of Spatial Video in Haiti

    PubMed Central

    Curtis, Andrew; Blackburn, Jason K.; Smiley, Sarah L.; Yen, Minmin; Camilli, Andrew; Alam, Meer Taifur; Ali, Afsar; Morris, J. Glenn

    2016-01-01

    The cartographic challenge in many developing world environments suffering a high disease burden is a lack of granular environmental covariates suitable for modeling disease outcomes. As a result, epidemiological questions, such as how disease diffuses at intra urban scales are extremely difficult to answer. This paper presents a novel geospatial methodology, spatial video, which can be used to collect and map environmental covariates, while also supporting field epidemiology. An example of epidemic cholera in a coastal town of Haiti is used to illustrate the potential of this new method. Water risks from a 2012 spatial video collection are used to guide a 2014 survey, which concurrently included the collection of water samples, two of which resulted in positive lab results “of interest” (bacteriophage specific for clinical cholera strains) to the current cholera situation. By overlaying sample sites on 2012 water risk maps, a further fifteen proposed water sample locations are suggested. These resulted in a third spatial video survey and an additional “of interest” positive water sample. A potential spatial connection between the “of interest” water samples is suggested. The paper concludes with how spatial video can be an integral part of future fine-scale epidemiological investigations for different pathogens. PMID:26848672

  14. Fine-scale genetic structure arises during range expansion of an invasive gecko.

    PubMed

    Short, Kristen Harfmann; Petren, Kenneth

    2011-01-01

    Processes of range expansion are increasingly important in light of current concerns about invasive species and range shifts due to climate change. Theoretical studies suggest that genetic structuring may occur during range expansion. Ephemeral genetic structure can have important evolutionary implications, such as propagating genetic changes along the wave front of expansion, yet few studies have shown evidence of such structure. We tested the hypothesis that genetic structure arises during range expansion in Hemidactylus mabouia, a nocturnal African gecko recently introduced to Florida, USA. Twelve highly variable microsatellite loci were used to screen 418 individuals collected from 43 locations from four sampling sites across Florida, representing a gradient from earlier (∼1990s) to very recent colonization. We found earlier colonized locations had little detectable genetic structure and higher allelic richness than more recently colonized locations. Genetic structuring was pronounced among locations at spatial scales of tens to hundreds of meters near the leading edge of range expansion. Despite the rapid pace of range expansion in this introduced gecko, dispersal is limited among many suitable habitat patches. Fine-scale genetic structure is likely the result of founder effects during colonization of suitable habitat patches. It may be obscured over time and by scale-dependent modes of dispersal. Further studies are needed to determine if such genetic structure affects adaptation and trait evolution in range expansions and range shifts.

  15. Fine-scale spatial genetic dynamics over the life cycle of the tropical tree Prunus africana

    PubMed Central

    Berens, D G; Braun, C; González-Martínez, S C; Griebeler, E M; Nathan, R; Böhning-Gaese, K

    2014-01-01

    Studying fine-scale spatial genetic patterns across life stages is a powerful approach to identify ecological processes acting within tree populations. We investigated spatial genetic dynamics across five life stages in the insect-pollinated and vertebrate-dispersed tropical tree Prunus africana in Kakamega Forest, Kenya. Using six highly polymorphic microsatellite loci, we assessed genetic diversity and spatial genetic structure (SGS) from seed rain and seedlings, and different sapling stages to adult trees. We found significant SGS in all stages, potentially caused by limited seed dispersal and high recruitment rates in areas with high light availability. SGS decreased from seed and early seedling stages to older juvenile stages. Interestingly, SGS was stronger in adults than in late juveniles. The initial decrease in SGS was probably driven by both random and non-random thinning of offspring clusters during recruitment. Intergenerational variation in SGS could have been driven by variation in gene flow processes, overlapping generations in the adult stage or local selection. Our study shows that complex sequential processes during recruitment contribute to SGS of tree populations. PMID:24849171

  16. Significant spatial aggregation and fine-scale genetic structure in the homosporous fern Cyrtomium falcatum (Dryopteridaceae).

    PubMed

    Chung, Mi Yoon; Chung, Myong Gi

    2013-08-01

    Spores of homosporous ferns are small, wind-borne and thus have the potential for long-distance dispersal. This common perception has led to a prediction of near-random spatial genetic structure within fern populations. Spore dispersal and spore bank studies, however, indicate that most spores fall close to the maternal plant (< 5 m), supporting a prediction of significant fine-scale genetic structure (FSGS) within populations. To determine which of these two hypotheses is more likely to occur in nature, we measured inbreeding and quantified the spatial distribution of individuals and allozyme-based genotypes using spatial autocorrelation methods within four populations of the fern Cyrtomium falcatum in southern South Korea. Inbreeding levels were low, and all populations exhibited significant aggregation of individuals and strong FSGS. The present results support the second hypothesis, and the substantial FSGS in C. falcatum could reflect the unique features of most homosporous ferns (outcrossing mating systems that lead a majority of spores to occur at short distances and a very limited dispersal distance of male gametes). Although fern spores are physically analogous to orchid seeds, the intensity of FSGS exhibited in C. falcatum is four times stronger than that in 16 terrestrial orchid species.

  17. Evaluation of summer precipitation from EURO-CORDEX fine-scale RCM simulations over Norway

    NASA Astrophysics Data System (ADS)

    Verpe Dyrrdal, Anita; Stordal, Frode; Lussana, Cristian

    2016-04-01

    Regional climate models is a valuable tool for local climate adaptation. Accurate estimates of future climate conditions are increasingly important, and in Norway precipitation is of special interest. Extreme precipitation, particularly over short durations, are responsible for enormous damages to important infrastructure, hence information on a fine spatial and temporal scale is crucial. We evaluate the ability of 7 fine-scale regional climate model simulations from the EURO-CORDEX ensemble in reproducing 3-hourly and daily summer precipitation characteristics in Norway, with an emphasis on extremes. The two-step evaluation includes comparison of modeled precipitation to gridded observation-based datasets and station measurements, in terms of the following indices: Summer maxima, summer wet event frequency, and total summer precipitation. We find a general overestimation by the models for all indices, with only few exceptions. Country-wide spatial averages show however that simulated summer extremes are mainly within the uncertainty interval of the reference dataset. A stronger overestimation of daily maxima compared to 3-hour maxima is evident, while the spread between models is larger for summer totals. We also find that the spatial distribution is fairly well simulated although the range of values in most models is too small. We believe that the high spatial resolution of 0.11° improves the simulations of extreme precipitation in Norway, especially in areas of orographic enhancement. However, a larger ensemble would be required in order to develop bias correction methods and analyse future projections of precipitation.

  18. Mapping to Support Fine Scale Epidemiological Cholera Investigations: A Case Study of Spatial Video in Haiti.

    PubMed

    Curtis, Andrew; Blackburn, Jason K; Smiley, Sarah L; Yen, Minmin; Camilli, Andrew; Alam, Meer Taifur; Ali, Afsar; Morris, J Glenn

    2016-02-03

    The cartographic challenge in many developing world environments suffering a high disease burden is a lack of granular environmental covariates suitable for modeling disease outcomes. As a result, epidemiological questions, such as how disease diffuses at intra urban scales are extremely difficult to answer. This paper presents a novel geospatial methodology, spatial video, which can be used to collect and map environmental covariates, while also supporting field epidemiology. An example of epidemic cholera in a coastal town of Haiti is used to illustrate the potential of this new method. Water risks from a 2012 spatial video collection are used to guide a 2014 survey, which concurrently included the collection of water samples, two of which resulted in positive lab results "of interest" (bacteriophage specific for clinical cholera strains) to the current cholera situation. By overlaying sample sites on 2012 water risk maps, a further fifteen proposed water sample locations are suggested. These resulted in a third spatial video survey and an additional "of interest" positive water sample. A potential spatial connection between the "of interest" water samples is suggested. The paper concludes with how spatial video can be an integral part of future fine-scale epidemiological investigations for different pathogens.

  19. Fine-scale genetic structure of grape phylloxera from the roots and leaves of Vitis.

    PubMed

    Corrie, A M; Hoffmann, A A

    2004-02-01

    Patterns of variation at microsatellite loci suggest that root populations of the pest grape phylloxera (Daktulosphaira vitifoliae) are largely parthenogenetic in Australian vineyards. To investigate reproduction in leaf galling phylloxera and the association between these individuals and phylloxera on roots, we examined in detail genetic variation in phylloxera from a vineyard block. Some genotypes found on leaf galls within this block were not present on roots, whereas others spanned both zones. There was no evidence that genotypes on roots were the product of sexual reproduction in leaf galls. mtDNA variation was not associated with the location of the phylloxera clones. The spatial distribution of genotypes within a root population was further investigated by intensively sampling phylloxera from another vineyard block. Join-count spatial autocorrelation statistics were used to explore fine-scale spatial structure. Clones were nonrandomly distributed within the block and there was evidence that the distribution of clones followed rows. These findings suggest firstly that there is limited dispersal of root and leaf feeding phylloxera, and secondly that factors, other than vine host, are likely to be important and contribute to clonal structure within populations.

  20. Fine-scale diversity and distribution of ectomycorrhizal fungal mycelium in a Scots pine forest.

    PubMed

    Anderson, Ian C; Genney, David R; Alexander, Ian J

    2014-03-01

    Ectomycorrhizal (ECM) mycelium is a key component of the ectomycorrhizal symbiosis, yet we know little regarding the fine-scale diversity and distribution of mycelium in ECM fungal communities. We collected four 20 × 20 × 2-cm(3) (800-cm(3)) slices of Scots pine (Pinus sylvestris) forest soil and divided each into 100 2 × 2 × 2-cm(3) (8-cm(3)) cubes. The presence of mycelium of ECM fungi was determined using an internal transcribed spacer (ITS) database terminal restriction fragment length polymorphism (T-RFLP) approach. As expected, many more ECM fungi were detected as mycelium than as ectomycorrhizas in a cube or slice. More surprisingly, up to one-quarter of the 43 species previously detected as ectomycorrhizas over an area of 400 m(2) could be detected in a single 8-cm(3) cube, and up to three-quarters in a single 800-cm(3) slice. ECM mycelium frequency decreased markedly with depth and there were distinct 'hotspots' of mycelium in the moss/F1 layer. Our data demonstrate a high diversity of ECM mycelium in a small (8-cm(3) ) volume of substrate, and indicate that the spatial scale at which ECM species are distributed as mycelium may be very different from the spatial scale at which they are distributed as tips.

  1. Population density and sex do not influence fine-scale natal dispersal in roe deer

    PubMed Central

    Gaillard, J.-M; Hewison, A.J.M; Kjellander, P; Pettorelli, N; Bonenfant, C; Van Moorter, B; Liberg, O; Andren, H; Van Laere, G; Klein, F; Angibault, J.-M; Coulon, A; Vanpé, C

    2008-01-01

    It is commonly assumed that the propensity to disperse and the dispersal distance of mammals should increase with increasing density and be greater among males than among females. However, most empirical evidence, especially on large mammals, has focused on highly polygynous and dimorphic species displaying female-defence mating tactics. We tested these predictions on roe deer, a weakly polygynous species of large herbivore exhibiting a resource-defence mating tactic at a fine spatial scale. Using three long-term studies of populations that were subject to the experimental manipulation of size, we did not find any support for either prediction, whether in terms of dispersal probability or dispersal distance. Our findings of similar dispersal patterns in both sexes of roe deer suggest that the underlying cause of natal dispersal is not related to inbreeding avoidance in this species. The absence of positive density dependence in fine-scale dispersal behaviour suggests that roe deer natal dispersal is a pre-saturation process that is shaped by heterogeneities in habitat quality rather than by density per se. PMID:18505718

  2. Population genomic footprints of fine-scale differentiation between habitats in Mediterranean blue tits.

    PubMed

    Szulkin, M; Gagnaire, P-A; Bierne, N; Charmantier, A

    2016-01-01

    Linking population genetic variation to the spatial heterogeneity of the environment is of fundamental interest to evolutionary biology and ecology, in particular when phenotypic differences between populations are observed at biologically small spatial scales. Here, we applied restriction-site associated DNA sequencing (RAD-Seq) to test whether phenotypically differentiated populations of wild blue tits (Cyanistes caeruleus) breeding in a highly heterogeneous environment exhibit genetic structure related to habitat type. Using 12 106 SNPs in 197 individuals from deciduous and evergreen oak woodlands, we applied complementary population genomic analyses, which revealed that genetic variation is influenced by both geographical distance and habitat type. A fine-scale genetic differentiation supported by genome- and transcriptome-wide analyses was found within Corsica, between two adjacent habitats where blue tits exhibit marked differences in breeding time while nesting < 6 km apart. Using redundancy analysis (RDA), we show that genomic variation remains associated with habitat type when controlling for spatial and temporal effects. Finally, our results suggest that the observed patterns of genomic differentiation were not driven by a small proportion of highly differentiated loci, but rather emerged through a process such as habitat choice, which reduces gene flow between habitats across the entire genome. The pattern of genomic isolation-by-environment closely matches differentiation observed at the phenotypic level, thereby offering significant potential for future inference of phenotype-genotype associations in a heterogeneous environment.

  3. Ventilated Oscillatory Boundary Layers

    DTIC Science & Technology

    1993-02-01

    AD-A266 226IllII !i III ll11111 II •" Ventilated Oscillatory Boundary Layers 0 Daniel -. Conley Douglas L. I nman C 0 UM U U U U till 1% w 1% W" Z t...A SIGNIFICANT NUMBER OF PAGES WHICH DO NOT REPRODUCE LEGIBLY. VENlTILATiD SCIILLAORY BOUNDARY LAYERS Daniel C. C7onley DoL’laN L. . ... La olDla...Wave Crest ........ 5. Boundary Layer Development Under the Wave Trough W 6 . Laboratory Observations .................. ................ 7

  4. The role of fine-scale anatomical structure in the dynamics of reentry in computational models of the rabbit ventricles

    PubMed Central

    Bishop, Martin J; Plank, Gernot

    2012-01-01

    Fine-scale anatomical structures in the heart may play an important role in sustaining cardiac arrhythmias. However, the extent of this role and how it may differ between species are not fully understood. In this study we used computational modelling to assess the impact of anatomy upon arrhythmia maintenance in the rabbit ventricles. Specifically, we quantified the dynamics of excitation wavefronts during episodes of simulated tachyarrhythmias and fibrillatory arrhythmias, defined as being respectively characterised by relatively low and high spatio-temporal disorganisation. Two computational models were used: a highly anatomically detailed MR-derived rabbit ventricular model (representing vasculature, endocardial structures) and a simplified equivalent model, constructed from the same MR-data but lacking such fine-scale anatomical features. During tachyarrhythmias, anatomically complex and simplified models showed very similar dynamics; however, during fibrillatory arrhythmias, as activation wavelength decreased, the presence of fine-scale anatomical details appeared to marginally increase disorganisation of wavefronts during arrhythmias in the complex model. Although a small amount of clustering of reentrant rotor centres (filaments) around endocardial structures was witnessed in follow-up analysis (which slightly increased during fibrillation as rotor size decreased), this was significantly less than previously reported in large animals. Importantly, no anchoring of reentrant rotors was visibly identifiable in arrhythmia movies. These differences between tachy- and fibrillatory arrhythmias suggest that the relative size of reentrant rotors with respect to anatomical obstacles governs the influence of fine-scale anatomy in the maintenance of ventricular arrhythmias in the rabbit. In conclusion, our simulations suggest that fine-scale anatomical features play little apparent role in the maintenance of tachyarrhythmias in the rabbit ventricles and, contrary to

  5. Ultra-Fine Scale Spatially-Integrated Mapping of Habitat and Occupancy Using Structure-From-Motion.

    PubMed

    McDowall, Philip; Lynch, Heather J

    2017-01-01

    Organisms respond to and often simultaneously modify their environment. While these interactions are apparent at the landscape extent, the driving mechanisms often occur at very fine spatial scales. Structure-from-Motion (SfM), a computer vision technique, allows the simultaneous mapping of organisms and fine scale habitat, and will greatly improve our understanding of habitat suitability, ecophysiology, and the bi-directional relationship between geomorphology and habitat use. SfM can be used to create high-resolution (centimeter-scale) three-dimensional (3D) habitat models at low cost. These models can capture the abiotic conditions formed by terrain and simultaneously record the position of individual organisms within that terrain. While coloniality is common in seabird species, we have a poor understanding of the extent to which dense breeding aggregations are driven by fine-scale active aggregation or limited suitable habitat. We demonstrate the use of SfM for fine-scale habitat suitability by reconstructing the locations of nests in a gentoo penguin colony and fitting models that explicitly account for conspecific attraction. The resulting digital elevation models (DEMs) are used as covariates in an inhomogeneous hybrid point process model. We find that gentoo penguin nest site selection is a function of the topography of the landscape, but that nests are far more aggregated than would be expected based on terrain alone, suggesting a strong role of behavioral aggregation in driving coloniality in this species. This integrated mapping of organisms and fine scale habitat will greatly improve our understanding of fine-scale habitat suitability, ecophysiology, and the complex bi-directional relationship between geomorphology and habitat use.

  6. Ultra-Fine Scale Spatially-Integrated Mapping of Habitat and Occupancy Using Structure-From-Motion

    PubMed Central

    McDowall, Philip; Lynch, Heather J.

    2017-01-01

    Organisms respond to and often simultaneously modify their environment. While these interactions are apparent at the landscape extent, the driving mechanisms often occur at very fine spatial scales. Structure-from-Motion (SfM), a computer vision technique, allows the simultaneous mapping of organisms and fine scale habitat, and will greatly improve our understanding of habitat suitability, ecophysiology, and the bi-directional relationship between geomorphology and habitat use. SfM can be used to create high-resolution (centimeter-scale) three-dimensional (3D) habitat models at low cost. These models can capture the abiotic conditions formed by terrain and simultaneously record the position of individual organisms within that terrain. While coloniality is common in seabird species, we have a poor understanding of the extent to which dense breeding aggregations are driven by fine-scale active aggregation or limited suitable habitat. We demonstrate the use of SfM for fine-scale habitat suitability by reconstructing the locations of nests in a gentoo penguin colony and fitting models that explicitly account for conspecific attraction. The resulting digital elevation models (DEMs) are used as covariates in an inhomogeneous hybrid point process model. We find that gentoo penguin nest site selection is a function of the topography of the landscape, but that nests are far more aggregated than would be expected based on terrain alone, suggesting a strong role of behavioral aggregation in driving coloniality in this species. This integrated mapping of organisms and fine scale habitat will greatly improve our understanding of fine-scale habitat suitability, ecophysiology, and the complex bi-directional relationship between geomorphology and habitat use. PMID:28076351

  7. Coexistence of sympatric carnivores in relatively homogeneous Mediterranean landscapes: functional importance of habitat segregation at the fine-scale level.

    PubMed

    Soto, Carolina; Palomares, Francisco

    2015-09-01

    One of the main objectives of community ecology is to understand the conditions allowing species to coexist. However, few studies have investigated the role of fine-scale habitat use segregation in the functioning of guild communities in relatively homogeneous landscapes where opportunities for coexistence are likely to be the most restrictive. We investigate how the process of habitat use differentiation at the home range level according to the degree of specialism/generalism of species can lead to coexistence between guild species. We examine differences in fine-scale habitat use and niche separation as potential mechanisms explaining the coexistence of five sympatric carnivore species that differ in life history traits (Iberian lynx, Eurasian badger, Egyptian mongoose, common genet and red fox) by collecting data from systematic track censuses in a relatively homogeneous Mediterranean landscape. We found that a higher degree of specialism determines the segregation of species among the fine-scale ecological niche dimensions defined using quantitative elements associated with vegetation, landscape, prey availability and human disturbance. The species with the lowest total performance over the set of variables did not exhibit segregation in the use of habitat at this level. Our study indicates that in relatively homogeneous landscapes, there exist subtle patterns of habitat partitioning over small-scale gradients of habitat determinants as a function of the degree of specialism of carnivore species within a guild. Our results also suggest that coexistence between generalist species may be permitted by fine-scale spatial-temporal segregation of activity patterns or trophic resource consumption, but not fine-scale habitat use differentiation.

  8. A standard cytogenetic map of Culex quinquefasciatus polytene chromosomes in application for fine-scale physical mapping.

    PubMed

    Unger, Maria F; Sharakhova, Maria V; Harshbarger, Adam J; Glass, Patrick; Collins, Frank H

    2015-06-06

    Southern house mosquito Culex quinquefasciatus belongs to the C. pipiens cryptic species complex, with global distribution and unclear taxonomy. Mosquitoes of the complex can transmit human and animal pathogens, such as filarial worm, West Nile virus and avian malarial Plasmodium. Physical gene mapping is crucial to understanding genome organization, function, and systematic relationships of cryptic species, and is a basis for developing new vector control strategies. However, physical mapping was not established previously for Culex due to the lack of well-structured polytene chromosomes. Inbreeding was used to diminish inversion polymorphism and asynapsis of chromosomal homologs. Identification of larvae of the same developmental stage using the shape of imaginal discs allowed achievement of uniformity in chromosomal banding pattern. This together with high-resolution phase-contrast photography enabled the development of a cytogenetic map. Fluorescent in situ hybridization was used for gene mapping. A detailed cytogenetic map of C. quinquefasciatus polytene chromosomes was produced. Landmarks for chromosome recognition and cytological boundaries for two inversions were identified. Locations of 23 genes belonging to 16 genomic supercontigs, and 2 cDNA were established. Six supercontigs were oriented and one was found putatively misassembled. The cytogenetic map was linked to the previously developed genetic linkage groups by corresponding positions of 2 genetic markers and 10 supercontigs carrying genetic markers. Polytene chromosomes were numbered according to the genetic linkage groups. This study developed a new standard cytogenetic photomap of the polytene chromosomes for C. quinquefasciatus and was applied for the fine-scale physical mapping. It allowed us to infer chromosomal position of 1333 of annotated genes belonging to 16 genomic supercontigs and find orientation of 6 of these supercontigs; the new cytogenetic and previously developed genetic linkage

  9. Strobes: an oscillatory combustion.

    PubMed

    Corbel, Justine M L; Lingen, Joost N J; Zevenbergen, John F; Gijzeman, Onno L J; Meijerink, Andries

    2012-04-26

    Strobe compositions belong to the class of solid combustions. They are mixtures of powdered ingredients. When ignited, the combustion front evolves in an oscillatory fashion, and flashes of light are produced by intermittence. They have fascinated many scientists since their discovery at the beginning of the 20th century. However, the chemical and physical processes involved in this curious oscillatory combustion remain unknown. Several theories have been proposed: One claims that two different reactions occur: one during the slow dark phase and another during the fast flash phase. The alternation between the phases is ascribed to heat variations. Other theories suggest that the formation of intermediate species during the dark phase and the change of phase are caused by variations in their concentration. A ternary strobe composition with ammonium perchlorate, magnalium, and barium sulfate is analyzed. The role of barium sulfate is studied by replacing it by other metal sulfates that have different physical properties (melting points), and the burning of the compositions is recorded with a high-speed camera and a spectrometer coupled with a charge-coupled device (CCD) camera. Experimental results show noticeable differences in the physical and chemical processes involved in the strobe reactions.

  10. Optimal Phase Oscillatory Network

    NASA Astrophysics Data System (ADS)

    Follmann, Rosangela

    2013-03-01

    Important topics as preventive detection of epidemics, collective self-organization, information flow and systemic robustness in clusters are typical examples of processes that can be studied in the context of the theory of complex networks. It is an emerging theory in a field, which has recently attracted much interest, involving the synchronization of dynamical systems associated to nodes, or vertices, of the network. Studies have shown that synchronization in oscillatory networks depends not only on the individual dynamics of each element, but also on the combination of the topology of the connections as well as on the properties of the interactions of these elements. Moreover, the response of the network to small damages, caused at strategic points, can enhance the global performance of the whole network. In this presentation we explore an optimal phase oscillatory network altered by an additional term in the coupling function. The application to associative-memory network shows improvement on the correct information retrieval as well as increase of the storage capacity. The inclusion of some small deviations on the nodes, when solutions are attracted to a false state, results in additional enhancement of the performance of the associative-memory network. Supported by FAPESP - Sao Paulo Research Foundation, grant number 2012/12555-4

  11. Evaluation of multispectral, fine scale digital imagery as a tool for mapping stream morphology

    NASA Astrophysics Data System (ADS)

    Wright, Andrea; Marcus, W. Andrew; Aspinall, Richard

    2000-05-01

    Multispectral digital imagery acquired from Soda Butte and Cache Creeks, Montana and Wyoming was used in conjunction with field data to classify and map hydrogeomorphic stream units on four stream reaches. The morphologic units that were field mapped were eddy drop zones, glides, low gradient riffles, high gradient riffles, lateral scour pools, attached bars, detached bars, and large woody debris. Unsupervised and supervised classifications of the imagery were used to develop a Maximum Joint Probability classification and an Alternative Joint Probability classification of the stream reaches. The Maximum Joint Probability classification allowed only one of the image classes to represent each hydrogeomorphic unit on the field map and resulted in relatively low overall accuracies for identification of these units of 10% to 50%. The Alternative Joint Probability classification allowed each image class to represent any geomorphic unit where the probability of a correct classification was greater than random. In this technique, two or three image classes were assigned to represent each hydrogeomorphic unit, resulting in higher overall accuracies of 28% to 80%. Accurate classification of hydrogeomorphic units was hampered by poor rectification of imagery with the field maps because of inadequate ground control points. In general, the largest hydrogeomorphic units were most accurately classified, whereas units that were small in area or spatially linear were least likely to be accurately classified. The results of this study demonstrated that multispectral digital imagery has the potential to be a useful tool for mapping hydrogeomorphic stream units at fine scales. Imagery to be an effective tool, however, careful measures such as accurate documentation of ground control points must be taken to ensure accurate rectification of the imagery with field maps.

  12. Predicting fine-scale distributions of peripheral aquatic species in headwater streams

    USGS Publications Warehouse

    DeRolph, Christopher R.; Nelson, S.; Kwak, Thomas J.; Hain, Ernie F.

    2015-01-01

    Headwater species and peripheral populations that occupy habitat at the edge of a species range may hold an increased conservation value to managers due to their potential to maximize intraspecies diversity and species' adaptive capabilities in the context of rapid environmental change. The southern Appalachian Mountains are the southern extent of the geographic range of native Salvelinus fontinalis and naturalized Oncorhynchus mykiss and Salmo trutta in eastern North America. We predicted distributions of these peripheral, headwater wild trout populations at a fine scale to serve as a planning and management tool for resource managers to maximize resistance and resilience of these populations in the face of anthropogenic stressors. We developed correlative logistic regression models to predict occurrence of brook trout, rainbow trout, and brown trout for every interconfluence stream reach in the study area. A stream network was generated to capture a more consistent representation of headwater streams. Each of the final models had four significant metrics in common: stream order, fragmentation, precipitation, and land cover. Strahler stream order was found to be the most influential variable in two of the three final models and the second most influential variable in the other model. Greater than 70% presence accuracy was achieved for all three models. The underrepresentation of headwater streams in commonly used hydrography datasets is an important consideration that warrants close examination when forecasting headwater species distributions and range estimates. Additionally, it appears that a relative watershed position metric (e.g., stream order) is an important surrogate variable (even when elevation is included) for biotic interactions across the landscape in areas where headwater species distributions are influenced by topographical gradients.

  13. Revealing fine scale subpopulation structure in the Vietnamese H'mong cattle breed for conservation purposes

    PubMed Central

    2010-01-01

    Background During the last decades, there has been an acceleration of the loss of domestic animal biodiversity. For conservation purposes, the genetic diversity of the H'Mong cattle, an indigenous local breed was studied. Single-nucleotide polymorphisms (SNP) of the SRY gene and mtDNA D-Loop sequence were analysed to clarify the origin of the breed. The genetic diversity was assessed through genetic data with twenty-five FAO microsatellites, and morphometric data with five body measurements from 408 animals sampled from eight districts of the Ha Giang province. Results The SRY genes were all of the zebu type. Among the 27 mtDNA haplotypes, 12 haplotypes were of the taurine type and the remaining 15 of the zebu type. This indicates female taurine introgression in the zebu H'Mong. The observed and expected heterozygosity ranged from 0.616 to 0.673 and from 0.681 to 0.729 respectively according to district, with low genetic differentiation (FST = 0.0076). Multivariate analysis on morphometric and genetic data shows a separation of districts into two groups following a south-west/north-east cline and admixture analysis confirmed the two clusters, but no differentiation of taurine introgression between clusters was observed. A possible admixture with the Yellow cattle breed from a neighbouring province was suggested through genetic data and householder interviews. Conclusions In this study we demonstrate the interest of fine-scale sampling for the study of genetic structure of local breeds. Such a study allows avoiding erroneous conservation policies and on the contrary, proposes measures for conserving and limiting crossbreeding between the H'Mong and the Yellow cattle breeds. PMID:20525403

  14. Predicting fine-scale distributions of peripheral aquatic species in headwater streams

    SciTech Connect

    DeRolph, Christopher R.; Nelson, Stacy A. C.; Kwak, Thomas J.; Hain, Ernie F.

    2014-12-09

    Headwater species and peripheral populations that occupy habitat at the edge of a species range may hold an increased conservation value to managers due to their potential to maximize intraspecies diversity and species' adaptive capabilities in the context of rapid environmental change. The southern Appalachian Mountains are the southern extent of the geographic range of native Salvelinus fontinalis and naturalized Oncorhynchus mykiss and Salmo trutta in eastern North America. In this paper, we predicted distributions of these peripheral, headwater wild trout populations at a fine scale to serve as a planning and management tool for resource managers to maximize resistance and resilience of these populations in the face of anthropogenic stressors. We developed correlative logistic regression models to predict occurrence of brook trout, rainbow trout, and brown trout for every interconfluence stream reach in the study area. A stream network was generated to capture a more consistent representation of headwater streams. Each of the final models had four significant metrics in common: stream order, fragmentation, precipitation, and land cover. Strahler stream order was found to be the most influential variable in two of the three final models and the second most influential variable in the other model. Greater than 70% presence accuracy was achieved for all three models. The underrepresentation of headwater streams in commonly used hydrography datasets is an important consideration that warrants close examination when forecasting headwater species distributions and range estimates. Finally and additionally, it appears that a relative watershed position metric (e.g., stream order) is an important surrogate variable (even when elevation is included) for biotic interactions across the landscape in areas where headwater species distributions are influenced by topographical gradients.

  15. Predicting fine-scale distributions of peripheral aquatic species in headwater streams

    DOE PAGES

    DeRolph, Christopher R.; Nelson, Stacy A. C.; Kwak, Thomas J.; ...

    2014-12-09

    Headwater species and peripheral populations that occupy habitat at the edge of a species range may hold an increased conservation value to managers due to their potential to maximize intraspecies diversity and species' adaptive capabilities in the context of rapid environmental change. The southern Appalachian Mountains are the southern extent of the geographic range of native Salvelinus fontinalis and naturalized Oncorhynchus mykiss and Salmo trutta in eastern North America. In this paper, we predicted distributions of these peripheral, headwater wild trout populations at a fine scale to serve as a planning and management tool for resource managers to maximize resistancemore » and resilience of these populations in the face of anthropogenic stressors. We developed correlative logistic regression models to predict occurrence of brook trout, rainbow trout, and brown trout for every interconfluence stream reach in the study area. A stream network was generated to capture a more consistent representation of headwater streams. Each of the final models had four significant metrics in common: stream order, fragmentation, precipitation, and land cover. Strahler stream order was found to be the most influential variable in two of the three final models and the second most influential variable in the other model. Greater than 70% presence accuracy was achieved for all three models. The underrepresentation of headwater streams in commonly used hydrography datasets is an important consideration that warrants close examination when forecasting headwater species distributions and range estimates. Finally and additionally, it appears that a relative watershed position metric (e.g., stream order) is an important surrogate variable (even when elevation is included) for biotic interactions across the landscape in areas where headwater species distributions are influenced by topographical gradients.« less

  16. Air pollution, health and social deprivation: A fine-scale risk assessment.

    PubMed

    Morelli, Xavier; Rieux, Camille; Cyrys, Josef; Forsberg, Bertil; Slama, Rémy

    2016-05-01

    Risk assessment studies often ignore within-city variations of air pollutants. Our objective was to quantify the risk associated with fine particulate matter (PM2.5) exposure in 2 urban areas using fine-scale air pollution modeling and to characterize how this risk varied according to social deprivation. In Grenoble and Lyon areas (0.4 and 1.2 million inhabitants, respectively) in 2012, PM2.5 exposure was estimated on a 10×10m grid by coupling a dispersion model to population density. Outcomes were mortality, lung cancer and term low birth weight incidences. Cases attributable to air pollution were estimated overall and stratifying areas according to the European Deprivation Index (EDI), taking 10µg/m(3) yearly average as reference (counterfactual) level. Estimations were repeated assuming spatial homogeneity of air pollutants within urban area. Median PM2.5 levels were 18.1 and 19.6μg/m(3) in Grenoble and Lyon urban areas, respectively, corresponding to 114 (5.1% of total, 95% confidence interval, CI, 3.2-7.0%) and 491 non-accidental deaths (6.0% of total, 95% CI 3.7-8.3%) attributable to long-term exposure to PM2.5, respectively. Attributable term low birth weight cases represented 23.6% of total cases (9.0-37.1%) in Grenoble and 27.6% of cases (10.7-42.6%) in Lyon. In Grenoble, 6.8% of incident lung cancer cases were attributable to air pollution (95% CI 3.1-10.1%). Risk was lower by 8 to 20% when estimating exposure through background stations. Risk was highest in neighborhoods with intermediate to higher social deprivation. Risk assessment studies relying on background stations to estimate air pollution levels may underestimate the attributable risk.

  17. Modeling plant species distributions under future climates: how fine scale do climate projections need to be?

    PubMed

    Franklin, Janet; Davis, Frank W; Ikegami, Makihiko; Syphard, Alexandra D; Flint, Lorraine E; Flint, Alan L; Hannah, Lee

    2013-02-01

    Recent studies suggest that species distribution models (SDMs) based on fine-scale climate data may provide markedly different estimates of climate-change impacts than coarse-scale models. However, these studies disagree in their conclusions of how scale influences projected species distributions. In rugged terrain, coarse-scale climate grids may not capture topographically controlled climate variation at the scale that constitutes microhabitat or refugia for some species. Although finer scale data are therefore considered to better reflect climatic conditions experienced by species, there have been few formal analyses of how modeled distributions differ with scale. We modeled distributions for 52 plant species endemic to the California Floristic Province of different life forms and range sizes under recent and future climate across a 2000-fold range of spatial scales (0.008-16 km(2) ). We produced unique current and future climate datasets by separately downscaling 4 km climate models to three finer resolutions based on 800, 270, and 90 m digital elevation models and deriving bioclimatic predictors from them. As climate-data resolution became coarser, SDMs predicted larger habitat area with diminishing spatial congruence between fine- and coarse-scale predictions. These trends were most pronounced at the coarsest resolutions and depended on climate scenario and species' range size. On average, SDMs projected onto 4 km climate data predicted 42% more stable habitat (the amount of spatial overlap between predicted current and future climatically suitable habitat) compared with 800 m data. We found only modest agreement between areas predicted to be stable by 90 m models generalized to 4 km grids compared with areas classified as stable based on 4 km models, suggesting that some climate refugia captured at finer scales may be missed using coarser scale data. These differences in projected locations of habitat change may have more serious implications than net

  18. Fine-scale tracking of marine turtles using GPS-Argos PTTs.

    PubMed

    Yasuda, Tohya; Arai, Nobuaki

    2005-05-01

    High-accuracy location data of wildlife telemetry using conventional satellite location systems are difficult to obtain. However, such data are necessary to clarify the nature of movements and home range sizes of animals. In order to measure the high-accuracy location data, we developed new GPS-Argos Platform Terminal Transmitters (PTTs) which transmit both the conventional location and GPS location simultaneously. Two experiments, one in an artificial rearing pond and the other in the open sea, were performed. First, two hawksbill turtles were tracked with the PTTs in a 5 ha breeding pond in Thailand. Their home ranges using both data were calculated and found to be 2.96 ha and 0.93 ha by the GPS data, and 156,740 ha and 184,478 ha by a conventional data. Secondly, a female green turtle attached with the GPS-Argos was released from the coast of Pangnga Province, Thailand. There was a relationship between depth and speed of travel based on the GPS data. The data from the PTT showed that the turtle moved south along the coastline at the depth of less than 20 m for 5 days, and then stayed at a depth of less than 10 m for 4 days. However, we could not find any clear relationship using conventional data. Only a meandering movement at a variety of depths was observed. The results of the two experiments indicated the PTTs have an enormous potential for enhancing our understanding of fine-scale movement patterns and home ranges of marine turtles.

  19. Fine-scale statistics of temperature and its derivatives in convective turbulence

    NASA Astrophysics Data System (ADS)

    Emran, M. S.; Schumacher, J.

    We study the fine-scale statistics of temperature and its derivatives in turbulent Rayleighnard convection. Direct numerical simulations are carried out in a cylindrical cell with unit aspect ratio filled with a fluid with Prandtl number equal to 0.7 for Rayleigh numbers between 107 and 109. The probability density function of the temperature or its fluctuations is found to be always non-Gaussian. The asymmetry and strength of deviations from the Gaussian distribution are quantified as a function of the cell height. The deviations of the temperature fluctuations from the local isotropy, as measured by the skewness of the vertical derivative of the temperature fluctuations, decrease in the bulk, but increase in the thermal boundary layer for growing Rayleigh number, respectively. Similarly to the passive scalar mixing, the probability density function of the thermal dissipation rate deviates significantly from a log-normal distribution. The distribution is fitted well by a stretched exponential form. The tails become more extended with increasing Rayleigh number which displays an increasing degree of small-scale intermittency of the thermal dissipation field for both the bulk and the thermal boundary layer. We find that the thermal dissipation rate due to the temperature fluctuations is not only dominant in the bulk of the convection cell, but also yields a significant contribution to the total thermal dissipation in the thermal boundary layer. This is in contrast to the ansatz used in scaling theories and can explain the differences in the scaling of the total thermal dissipation rate with respect to the Rayleigh number.

  20. Fine-scale predictions of distributions of Chagas disease vectors in the state of Guanajuato, Mexico.

    PubMed

    López-Cárdenas, Jorge; Gonzalez Bravo, Francisco Ernesto; Salazar Schettino, Paz Maria; Gallaga Solorzano, Juan Carlos; Ramírez Barba, Ector; Martinez Mendez, Joel; Sánchez-Cordero, V; Peterson, A Townsend; Ramsey, J M

    2005-11-01

    One of the most daunting challenges for Chagas disease surveillance and control in Mexico is the lack of community level data on vector distributions. Although many states now have assembled representative domestic triatomine collections, only two triatomine specimens had been collected and reported previously from the state of Guanajuato. Field personnel from the state's Secretaría de Salud conducted health promotion activities in 43 of the 46 counties in the state and received donations of a total of 2,522 triatomine specimens between 1998 and 2002. All specimens were identified, and live insects examined for Trypanosoma cruzi. In an effort to develop fine-scale distributional data for Guanajuato, collection localities were georeferenced and ecological niches were modeled for each species by using evolutionary-computing approaches. Five species were collected: Triatoma mexicana (Herrich-Schaeffer), Triatoma longipennis (Usinger), Triatoma pallidipennis (Stål), Triatoma barberi (Usinger), and Triatoma dimidiata (Latreille) from 201 communities located at elevations of 870-2,200 m. Based on collection success, T. mexicana had the broadest dispersion, although niche mapping indicates that T. barberi represents the greatest risk for transmission of Chagas disease in the state. T. dimidiata was represented in collections by a single adult collected from one village outside the predicted area for all species. For humans, an estimated 3,755,380 individuals are at risk for vector transmission in the state, with an incidence of 3,500 new cases per year; overall seroprevalences of 2.6% indicate that 97,640 individuals are infected with T. cruzi at present, including 29,300 chronic cases.

  1. Imaging of Non-Resolved Objects Using the Fine Scale Optical Range

    NASA Astrophysics Data System (ADS)

    Pollock, T.; Grubb, P. M.

    2012-09-01

    The Fine Scale Optical Range (FiScOR) has been designed and assembled at the Space Engineering Research Center(SERC) at Texas A&M University to study the efficacy of on-orbit debris characterization using small space-based cameras. Physically, this facility permits imaging of small, one to two centimeter models of simple or complex shapes from a distance sufficiently great to produce image sizes of about one pixel. The objects are designed in 3D CAD and produced in plastic by 3D printing. They are then surfaced with real materials such as multi-layer insulation (MLI) and silicon solar cell fragments. Details, such as slight faceting in solar cell arrays, are achieved to dimensions as fine as 200 micrometers. Mechanisms are provided to rotate and translate the object. Illumination sources approximating the solar spectrum are used. Light curves are recorded using CCD or CMOS cameras which may be cooled or operated at ambient temperature. This research supports a more extensive body of work for the Air Force Research Lab and others examining image processing with noise terms for cameras imaging in visible and near-visible light, and assessing operational effects using synthetic space images created in the lab. For the study reported herein, a few simple objects (cubes, cylinders, etc.), two satellite models, and some shapes representing debris were imaged using a high frame rate color (Bayer mask) camera. Data obtained were compared with Phong models, and to a limited extent, with night sky images obtained using the 0.8m telescope near Stephenville, TX and smaller instruments located near College Station, TX. In some tests, low lighting levels were used to permit estimation of the maximum range at which an equivalent orbiting object would be detected by a particular camera/lens combination. Results demonstrating the potential contribution of this approach to non resolved space object characterization will be presented.

  2. Fine Scale ANUClimate Data for Ecosystem Modeling and Assessment of Plant Functional Types

    NASA Astrophysics Data System (ADS)

    Hutchinson, M. F.; Kesteven, J. L.; Xu, T.; Evans, B. J.; Togashi, H. F.; Stein, J. L.

    2015-12-01

    High resolution spatially extended values of climate variables play a central role in the assessment of climate and projected future climate in ecosystem modeling. The ground based meteorological network remains a key resource for deriving these spatially extended climate variables. We report on the production, and applications, of new anomaly based fine scale spatial interpolations of key climate variables at daily and monthly time scale, across the Australian continent. The methods incorporate several innovations that have significantly improved spatial predictive accuracy, as well as providing a platform for the incorporation of additional remotely sensed data. The interpolated climate data are supporting many continent-wide ecosystem modeling applications and are playing a key role in testing optimality hypotheses associated with plant functional types (PFTs). The accuracy, and robustness to data error, of anomaly-based interpolation has been enhanced by incorporating physical process aspects of the different climate variables and employing robust statistical methods implemented in the ANUSPLIN package. New regression procedures have also been developed to estimate "background" monthly climate normals from all stations with minimal records to substantially increase the density of supporting spatial networks. Monthly mean temperature interpolation has been enhanced by incorporating process based coastal effects that have reduced predictive error by around 10%. Overall errors in interpolated monthly temperature fields are around 25% less than errors reported by an earlier study. For monthly and daily precipitation, a new anomaly structure has been devised to take account of the skewness in precipitation data and the large proportion of zero values that present significant challenges to standard interpolation methods. The many applications include continent-wide Gross Primary Production modeling and assessing constraints on light and water use efficiency derived

  3. The empirical Bayes estimators of fine-scale population structure in high gene flow species.

    PubMed

    Kitada, Shuichi; Nakamichi, Reiichiro; Kishino, Hirohisa

    2017-02-27

    An empirical Bayes (EB) pairwise FST estimator was previously introduced and evaluated for its performance by numerical simulation. In this study, we conducted coalescent simulations and generated genetic population structure mechanistically, and compared the performance of the EBFST with Nei's GST , Nei & Chesser's bias-corrected GST (GST _NC ), Weir & Cockerham's ϴ (ϴWC ),( and ϴ with finite sample correction (ϴWC _F ). We also introduced EB estimators for Hedrick' G'ST and Jost' D. We applied these estimators to publicly available SNP genotypes of Atlantic herring. We also examined the power to detect the environmental factors causing the population structure. Our coalescent simulations revealed that the finite sample correction of ϴWC is necessary to assess population structure using pairwise FST values. For microsatellite markers, EBFST performed the best among the present estimators regarding both bias and precision under high gene flow scenarios (FST >0.032). For 300 SNPs, EBFST had the highest precision in all cases, but the bias was negative and greater than those for GST_NC and (ϴWC_F ) in all cases. GST_NC and (ϴWC_F ) performed very similarly at all levels of FST . As the number of loci increased up to 10 000, the precision of GST_NC and ϴWC_F became slightly better than for EBFST for cases with FST >0.004, even though the size of the bias remained constant. The EB estimators described the fine-scale population structure of the herring, and revealed that ~56% of the genetic differentiation was caused by sea surface temperature and salinity. The R package FINEPOP for implementing all estimators used here is available on CRAN. This article is protected by copyright. All rights reserved.

  4. Fine-Scale Population Recombination Rates, Hotspots, and Correlates of Recombination in the Medicago truncatula Genome

    PubMed Central

    Paape, Timothy; Zhou, Peng; Branca, Antoine; Briskine, Roman; Young, Nevin; Tiffin, Peter

    2012-01-01

    Recombination rates vary across the genome and in many species show significant relationships with several genomic features, including distance to the centromere, gene density, and GC content. Studies of fine-scale recombination rates have also revealed that in several species, there are recombination hotspots, that is, short regions with recombination rates 10–100 greater than those in surrounding regions. In this study, we analyzed whole-genome resequence data from 26 accessions of the model legume Medicago truncatula to gain insight into the genomic features that are related to high- and low-recombination rates and recombination hotspots at 1 kb scales. We found that high-recombination regions (1-kb windows among those in the highest 5% of the distribution) on all three chromosomes were significantly closer to the centromere, had higher gene density, and lower GC content than low-recombination windows. High-recombination windows are also significantly overrepresented among some gene functional categories—most strongly NB–ARC and LRR genes, both of which are important in plant defense against pathogens. Similar to high-recombination windows, recombination hotspots (1-kb windows with significantly higher recombination than the surrounding region) are significantly nearer to the centromere than nonhotspot windows. By contrast, we detected no difference in gene density or GC content between hotspot and nonhotspot windows. Using linear model wavelet analysis to examine the relationship between recombination and genomic features across multiple spatial scales, we find a significant negative correlation with distance to the centromere across scales up to 512 kb, whereas gene density and GC content show significantly positive and negative correlations, respectively, only up to 64 kb. Correlations between recombination and genomic features, particularly gene density and polymorphism, suggest that they are scale dependent and need to be assessed at scales relevant

  5. Using Sensitivity Analysis and Fine-Scale Field Measurements to Understand How Canopy Interception Models Function

    NASA Astrophysics Data System (ADS)

    Siegert, C. M.; Levia, D. F., Jr.; Dowtin, A. L.; Hudson, S.; Linhoss, A.

    2015-12-01

    The capacity of the forest canopy to intercept precipitation and partition the remaining water into throughfall and stemflow largely influences the surface water budget in forested ecosystems. These processes are controlled by species-specific traits, canopy seasonality, and meteorological conditions. The complexity of these interacting factors at varying temporal and spatial scales can lead to errors in estimating canopy interception and reduce accuracy of derivative watershed hydrologic modeling efforts. To improve interception estimates, model calibration and validation must be assessed using long-term, fine-scale field measurements that capture the variability of all interacting factors. As such, field measurements of subcanopy hydrologic fluxes and meteorological conditions during discrete storm events were taken from 2007 to 2012 in a deciduous forest dominated by Fagus grandifolia and Liriodendron tulipifera in Fair Hill, Maryland, USA. Preliminary results suggest that many of the current interception models (e.g., Gash and Rutter-types) are driven primarily by evaporation terms. However, field measurements indicate that a large degree of variability in both throughfall and stemflow partitioning is derived from biophysical characteristics. For example, even within the small 12-hectare research catchment, differences in species composition induced by slight changes in elevation, coupled with slope orientation, resulted in sufficient canopy variability whereby throughfall fluxes were definitively different across small distances. Additionally, smaller trees were more efficient in generating stemflow, while species with smoother bark generated large quantities of stemflow under a variety of storm conditions—a mechanism that may further confound modeling efforts. To improve canopy interception estimates, model sensitivity analysis was used to determine the influence of current model parameters and how biophysical canopy characteristics may be further

  6. The fine-scale vertical variability of a wastewater plume in shallow, stratified coastal waters

    NASA Astrophysics Data System (ADS)

    Lucas, Andrew J.; Kudela, Raphael M.

    2017-02-01

    We observed the fine-scale vertical variability of a wastewater plume discharged into shallow, stratified coastal waters with a set of wave-powered profiling moorings and bottom-mounted Acoustic Doppler Current Profilers. These in situ observations demonstrated that the effluent plume occupied a variable portion of the water column, but was typically at or above the pycnocline. The plume was characterized by small vertical scales away from the surface, while complicated patterns of vertical temperature and salinity compensation were found in the plume above the pycnocline. The particular design of the diffuser led to an effluent plume that was roughly split between depth-trapped and trapped at the surface. Estimates of dilution from temperature/salinity diagrams indicated that the plume dilution ranged between 60 and 120, and that the environmental mixing end-members ranged from waters well below the pycnocline to the waters at or near the surface. Far from the outfall, oceanographic variability at frequencies equal to and higher than the diurnal frequency dominated the vertical shear in local currents and thus the vertical and temporal distribution of the plume. Mixing driven by the high frequency non-linear internal waves and bore-like manifestations of the cross-shore baroclinic tide, as suggested by elevated inverse Richardson number within the leading and trailing edge of the bores, was likely the primary source of mixing between the plume and ambient waters far from the outfall. Complicated patterns in plume water characteristics demonstrated the complexity of the plume dilution even in a surfacing plume. The co-occurrence of elevated chlorophyll fluorescence and plume waters was evident in the later part of the diversion period, but the overall response of the phytoplankton to the effluent diversion was limited. Implications for outfall wastewater monitoring and diffuser design are briefly considered.

  7. Fine-scale structure of the neutral ISM in M81

    NASA Astrophysics Data System (ADS)

    Bagetakos, Ioannis; Brinks, Elias; Walter, Fabian; de Blok, Erwin

    We present an analysis of the fine-scale structure of the neutral ISM as traced via the 21-cm line of atomic hydrogen (HI) in the nearby galaxy M81. This galaxy forms part of "The HI Nearby Galaxy Survey" (THINGS), a survey performed with the NRAO Very Large Array resulting in data with 7" angular and 5 km s^-1 or better velocity resolution. The data show a stunning amount of detail in the form of 330 expanding shells and holes in the neutral ISM of M81. A comparison with the holes found in two other spirals and two dwarf galaxies (M31, M33, IC 2574 and Holmberg II) reveals that the ISM in M81 shares a lot of similarities with the two spirals, whereas the structure of its ISM is different to that in dwarf galaxies. The two properties which most clearly illustrate this are the size distribution of the HI holes and their distribution in velocity. Our observations reinforce the idea that the amount of energy typically deposited in the ISM is the same, irrespective of galaxy type, but that the properties of HI holes depend on the characteristics of the host galaxy, notably the thickness of the neutral gas layer. Also, there seems to be a clear indication that HI holes in spiral galaxies are shorter-lived, most likely due to the combined effects of shear and spiral density waves. The sizes of the HI holes in M81 range from 80 pc (close to the resolution limit) to 600 pc; the expansion velocities can reach 20 km s^-1; estimated ages are 2.5 to 35 Myrs and the energies involved range from 10^50 to 3.5 x 10^52 ergs. The amount of neutral gas involved is of order 10^4 to 10^6 solar masses.

  8. Altimetric lagrangian advection to reconstruct Pacific Ocean fine scale surface tracer fields

    NASA Astrophysics Data System (ADS)

    Rogé, Marine; Morrow, Rosemary; Dencausse, Guillaume

    2015-04-01

    In past studies, lagrangian stirring of surface tracer fields by altimetric surface geostrophic currents has been performed in different mid to high-latitude regions, showing good results in reconstructing finer-scale tracer patterns. Here we apply the technique to three different regions in the eastern and western tropical Pacific, and in the subtropical southwest Pacific. Initial conditions are derived from weekly gridded temperature and salinity fields, based on hydrographic data and Argo. Validation of the improved fine-scale surface tracer fields is performed using satellite AMSRE SST data, and high-resolution ship thermosalinograph data. We test two kinds of lagrangian advection. The standard one-way advection is shown to introduce an increased tracer bias as the advection time increases. Indeed, since we only use passive stirring, a bias is introduced from the missing physics, such as air-sea fluxes or mixing. A second "backward-forward" advection technique is shown to reduce the seasonal bias, but more data is lost around coasts and islands, a strong handicap in the tropical Pacific with many small islands. In the subtropical Pacific Ocean, the mesoscale temperature and salinity fronts are well represented by the one-way advection over a 10-day advection time, including westward propagating features not apparent in the initial fields. In the tropics, the results are less clear. The validation is hampered by the complex vertical stratification, and the technique is limited by the lack of accurate surface currents for the stirring - the gridded altimetric fields poorly represent the meridional currents, and are not detecting the fast tropical instability waves, nor the wind-driven circulation. We suggest that the passive lateral stirring technique is efficient in regions with moderate the high mesoscale energy and correlated mesoscale surface temperature and surface height. In other regions, more complex dynamical processes may need to be included.

  9. Causes and consequences of fine-scale population structure in a critically endangered freshwater seal

    PubMed Central

    2014-01-01

    Background Small, genetically uniform populations may face an elevated risk of extinction due to reduced environmental adaptability and individual fitness. Fragmentation can intensify these genetic adversities and, therefore, dispersal and gene flow among subpopulations within an isolated population is often essential for maintaining its viability. Using microsatellite and mtDNA data, we examined genetic diversity, spatial differentiation, interregional gene flow, and effective population sizes in the critically endangered Saimaa ringed seal (Phoca hispida saimensis), which is endemic to the large but highly fragmented Lake Saimaa in southeastern Finland. Results Microsatellite diversity within the subspecies (HE = 0.36) ranks among the lowest thus far recorded within the order Pinnipedia, with signs of ongoing loss of individual heterozygosity, reflecting very low effective subpopulation sizes. Bayesian assignment analyses of the microsatellite data revealed clear genetic differentiation among the main breeding areas, but interregional structuring was substantially weaker in biparentally inherited microsatellites (FST = 0.107) than in maternally inherited mtDNA (FST = 0.444), indicating a sevenfold difference in the gene flow mediated by males versus females. Conclusions Genetic structuring in the population appears to arise from the joint effects of multiple factors, including small effective subpopulation sizes, a fragmented lacustrine habitat, and behavioural dispersal limitation. The fine-scale differentiation found in the landlocked Saimaa ringed seal is especially surprising when contrasted with marine ringed seals, which often exhibit near-panmixia among subpopulations separated by hundreds or even thousands of kilometres. Our results demonstrate that population structures of endangered animals cannot be predicted based on data on even closely related species or subspecies. PMID:25005257

  10. Inferring natural selection on fine-scale chromatin organization in yeast.

    PubMed

    Babbitt, G A; Kim, Y

    2008-08-01

    Despite its potential role in the evolution of complex phenotypes, the detection of negative (purifying) and positive selection on noncoding regulatory sequence has been elusive because of the inherent difficulty in predicting the functional consequences of mutations on noncoding sequence. Because the functioning of regulatory sequence depends upon both chromatin configuration and cis-regulatory factor binding, we investigate the idea that the functional conservation of regulatory regions should be associated with the conservation of sequence-dependent bending properties of DNA that determine its affinity for the nucleosome. Recent advances in the computational prediction of sequence-dependent affinity to nucleosomes provide an opportunity to distinguish between neutral and nonneutral evolution of fine-scale chromatin organization. Here, a statistical test is presented for detecting evolutionary conservation and/or adaptive evolution of nucleosome affinity from interspecies comparisons of DNA sequences. Local nucleosome affinities of homologous sequences were calculated using 2 recently published methods. A randomization test was applied to sites of mutation to evaluate the similarity of DNA-nucleosome affinity between several closely related species of Saccharomyces yeast. For most of the genes we analyzed, the conservation of local nucleosome affinity was detected at a few distinct locations in the upstream noncoding region. Our results also demonstrate that different patterns of chromatin evolution have shaped DNA-nucleosome interaction at the core promoters of TATA-containing and TATA-less genes and that elevated purifying selection has maintained low affinity for nucleosome in the core promoters of the latter group. Across the entire yeast genome, DNA-nucleosome interaction was also discovered to be significantly more conserved in TATA-less genes compared with TATA-containing genes.

  11. Regulation of the Demographic Structure in Isomorphic Biphasic Life Cycles at the Spatial Fine Scale

    PubMed Central

    Vieira, Vasco Manuel Nobre de Carvalho da Silva; Mateus, Marcos Duarte

    2014-01-01

    Isomorphic biphasic algal life cycles often occur in the environment at ploidy abundance ratios (Haploid:Diploid) different from 1. Its spatial variability occurs within populations related to intertidal height and hydrodynamic stress, possibly reflecting the niche partitioning driven by their diverging adaptation to the environment argued necessary for their prevalence (evolutionary stability). Demographic models based in matrix algebra were developed to investigate which vital rates may efficiently generate an H:D variability at a fine spatial resolution. It was also taken into account time variation and type of life strategy. Ploidy dissimilarities in fecundity rates set an H:D spatial structure miss-fitting the ploidy fitness ratio. The same happened with ploidy dissimilarities in ramet growth whenever reproductive output dominated the population demography. Only through ploidy dissimilarities in looping rates (stasis, breakage and clonal growth) did the life cycle respond to a spatially heterogeneous environment efficiently creating a niche partition. Marginal locations were more sensitive than central locations. Related results have been obtained experimentally and numerically for widely different life cycles from the plant and animal kingdoms. Spore dispersal smoothed the effects of ploidy dissimilarities in fertility and enhanced the effects of ploidy dissimilarities looping rates. Ploidy dissimilarities in spore dispersal could also create the necessary niche partition, both over the space and time dimensions, even in spatial homogeneous environments and without the need for conditional differentiation of the ramets. Fine scale spatial variability may be the key for the prevalence of isomorphic biphasic life cycles, which has been neglected so far. PMID:24658603

  12. Predicting fine-scale distributions of peripheral aquatic species in headwater streams

    PubMed Central

    DeRolph, Christopher R; Nelson, Stacy A C; Kwak, Thomas J; Hain, Ernie F

    2015-01-01

    Headwater species and peripheral populations that occupy habitat at the edge of a species range may hold an increased conservation value to managers due to their potential to maximize intraspecies diversity and species' adaptive capabilities in the context of rapid environmental change. The southern Appalachian Mountains are the southern extent of the geographic range of native Salvelinus fontinalis and naturalized Oncorhynchus mykiss and Salmo trutta in eastern North America. We predicted distributions of these peripheral, headwater wild trout populations at a fine scale to serve as a planning and management tool for resource managers to maximize resistance and resilience of these populations in the face of anthropogenic stressors. We developed correlative logistic regression models to predict occurrence of brook trout, rainbow trout, and brown trout for every interconfluence stream reach in the study area. A stream network was generated to capture a more consistent representation of headwater streams. Each of the final models had four significant metrics in common: stream order, fragmentation, precipitation, and land cover. Strahler stream order was found to be the most influential variable in two of the three final models and the second most influential variable in the other model. Greater than 70% presence accuracy was achieved for all three models. The underrepresentation of headwater streams in commonly used hydrography datasets is an important consideration that warrants close examination when forecasting headwater species distributions and range estimates. Additionally, it appears that a relative watershed position metric (e.g., stream order) is an important surrogate variable (even when elevation is included) for biotic interactions across the landscape in areas where headwater species distributions are influenced by topographical gradients. PMID:25628872

  13. Fine-scale genetic analysis of the exploited Nile monitor (Varanus niloticus) in Sahelian Africa.

    PubMed

    Dowell, Stephanie A; de Buffrénil, Vivian; Kolokotronis, Sergios-Orestis; Hekkala, Evon R

    2015-03-28

    Overexploitation of wildlife populations results in direct consequences, such as extinction and local extirpation, as well as indirect effects including genetic diversity loss and changes in genetic structure. A clear understanding of the underlying genetic patterns of harvested species is necessary for sustainable management. The Nile monitor (Varanus niloticus) is a commercially valuable species in the international leather industry, with the highest levels of exploitation concentrated throughout Sahelian Africa. In this study, we examined the fine-scale genetic patterns of V. niloticus populations in the Sahel, with the expectation that the genetic structure would correspond to riverine drainage basins. The analyses were based on genotypes at 11 microsatellite loci for 318 individuals, spanning three separate watersheds throughout the Sahel. Our analyses identified four genetic clusters throughout the region, one of which (the westernmost population) exhibited very high levels of genetic differentiation (FST = 0.47). Contrary to our expectation, the largest genetic break occurred within a single watershed, the Niger basin, rather than between watersheds. However, other localities displayed evidence of reduced gene flow between watershed boundaries. Across methods, the westernmost population exhibited lower estimates of N e as well as lower levels of genetic diversity compared to the other inferred populations. While we did not detect evidence for recent population bottlenecks, our analyses indicated historic population declines around 1,000-1,800 years ago. We found that the underlying genetic structure of Varanus niloticus across Sahelian Africa reflects historic as well as present-day patterns of riverine drainages. The high degree of differentiation found for the westernmost population indicates the presence of a separate lineage, and should be taken into consideration when setting harvest limits. The historic population decline for two of the populations

  14. Using fine-scale fuel measurements to assess wildland fuels, potential fire behavior and hazard mitigation treatments in the southeastern USA

    Treesearch

    Roger D. Ottmar; John I. Blake; William T. Crolly

    2012-01-01

    The inherent spatial and temporal heterogeneity of fuel beds in forests of the southeastern United States may require fine scale fuel measurements for providing reliable fire hazard and fuel treatment effectiveness estimates. In a series of five papers, an intensive, fine scale fuel inventory from the Savanna River Site in the southeastern United States is used for...

  15. The wildland fuel cell concept: an approach to characterize fine-scale variation in fuels and fire in frequently burned longleaf pine forests

    Treesearch

    J. Kevin Hiers; Joseph J. O’Brien; R. J. Mitchell; John M. Grego; E. Louise Loudermilk

    2009-01-01

    In ecosystems with frequent surface fire regimes, fire and fuel heterogeneity has been largely overlookedowing to the lack of unburned patches and the difficulty in measuring fire behavior at fine scales (0.1–10 m). The diversevegetation in these ecosystems varies at these fine scales. This diversity could be...

  16. Oscillatory threshold logic.

    PubMed

    Borresen, Jon; Lynch, Stephen

    2012-01-01

    In the 1940s, the first generation of modern computers used vacuum tube oscillators as their principle components, however, with the development of the transistor, such oscillator based computers quickly became obsolete. As the demand for faster and lower power computers continues, transistors are themselves approaching their theoretical limit and emerging technologies must eventually supersede them. With the development of optical oscillators and Josephson junction technology, we are again presented with the possibility of using oscillators as the basic components of computers, and it is possible that the next generation of computers will be composed almost entirely of oscillatory devices. Here, we demonstrate how coupled threshold oscillators may be used to perform binary logic in a manner entirely consistent with modern computer architectures. We describe a variety of computational circuitry and demonstrate working oscillator models of both computation and memory.

  17. Oscillatory Threshold Logic

    PubMed Central

    Borresen, Jon; Lynch, Stephen

    2012-01-01

    In the 1940s, the first generation of modern computers used vacuum tube oscillators as their principle components, however, with the development of the transistor, such oscillator based computers quickly became obsolete. As the demand for faster and lower power computers continues, transistors are themselves approaching their theoretical limit and emerging technologies must eventually supersede them. With the development of optical oscillators and Josephson junction technology, we are again presented with the possibility of using oscillators as the basic components of computers, and it is possible that the next generation of computers will be composed almost entirely of oscillatory devices. Here, we demonstrate how coupled threshold oscillators may be used to perform binary logic in a manner entirely consistent with modern computer architectures. We describe a variety of computational circuitry and demonstrate working oscillator models of both computation and memory. PMID:23173034

  18. Detection of a Fine-scale Discontinuity of Photospheric Magnetic Fields Associated with Solar Coronal Loop Brightenings

    NASA Astrophysics Data System (ADS)

    Song, Donguk; Chae, Jongchul; Park, Soyoung; Cho, Kyung-Suk; Lim, Eun-Kyung; Ahn, Kwangsu; Cao, Wenda

    2015-09-01

    We present the transient brightening of a coronal loop and an associated fine-scale magnetic discontinuity detected in the photosphere. Utilizing the high-resolution data taken with the Fast Imaging Solar Spectrograph and InfraRed Imaging Magnetograph of the New Solar Telescope at Big Bear Solar Observatory, we detect a narrow lane of intense horizontal magnetic field representing a magnetic discontinuity. It was visible as a dark lane partially encircling a pore in the continuum image, and was located near one of the footpoints of a small coronal loop that experienced transient brightenings. The horizontal field strength gradually increased before the loop brightening, and then rapidly decreased in the impulsive phase of the brightening, suggesting the increase of the magnetic non-potentiality at the loop footpoint and the sudden release of magnetic energy via magnetic reconnection. Our results support the nanoflare theory that coronal heating events are caused by magnetic reconnection events at fine-scale magnetic discontinuities.

  19. Combined atom-probe and electron microscopy characterization of fine scale structures in aged primary coolant pipe stainless steel

    SciTech Connect

    Bentley, J.; Miller, M.K.

    1986-01-01

    The capabilities and complementary nature of atom probe field-ion microscopy (APFIM) and analytical electron microscopy (AEM) for the characterization of fine-scale microstructures are illustrated by examination of the changes that occur after long term thermal aging of cast CF 8 and CF 8M duplex stainless steels. In material aged at 300 or 400/sup 0/C for up to 70,000 h, the ferrite had spinodally decomposed into a modulated fine-scaled interconnected network consisting of an iron-rich ..cap alpha.. phase and a chromium-enriched ..cap alpha..' phase with periodicities of between 2 and 9 nm. G-phase precipitates 2 to 10 nm in diameter were also observed in the ferrite at concentrations of more than 10/sup 21/ m/sup -3/. The reported degradation in mechanical properties is most likely a consequence of the spinodal decomposition in the ferrite.

  20. DETECTION OF A FINE-SCALE DISCONTINUITY OF PHOTOSPHERIC MAGNETIC FIELDS ASSOCIATED WITH SOLAR CORONAL LOOP BRIGHTENINGS

    SciTech Connect

    Song, Donguk; Chae, Jongchul; Park, Soyoung; Cho, Kyung-Suk; Lim, Eun-Kyung; Ahn, Kwangsu; Cao, Wenda

    2015-09-10

    We present the transient brightening of a coronal loop and an associated fine-scale magnetic discontinuity detected in the photosphere. Utilizing the high-resolution data taken with the Fast Imaging Solar Spectrograph and InfraRed Imaging Magnetograph of the New Solar Telescope at Big Bear Solar Observatory, we detect a narrow lane of intense horizontal magnetic field representing a magnetic discontinuity. It was visible as a dark lane partially encircling a pore in the continuum image, and was located near one of the footpoints of a small coronal loop that experienced transient brightenings. The horizontal field strength gradually increased before the loop brightening, and then rapidly decreased in the impulsive phase of the brightening, suggesting the increase of the magnetic non-potentiality at the loop footpoint and the sudden release of magnetic energy via magnetic reconnection. Our results support the nanoflare theory that coronal heating events are caused by magnetic reconnection events at fine-scale magnetic discontinuities.

  1. Fine Scale Structure observed in the Total Electron Content above the Sub-Auroral, Auroral, and Polar Ionosphere

    NASA Astrophysics Data System (ADS)

    Coster, A. J.; Thomas, E. G.; Vierinen, J.; Rideout, W. E.

    2015-12-01

    This paper details recent improvements in TEC observations made in the sub-auroral, auroral, and polar regions. The goal is high-resolution measurements of both medium and fine-scale TEC-gradients. To achieve this, the number of GNSS receivers processed was more than doubled, due to agreements made with multiple government and commercial agencies, such as those involved with highway transportation and precision farming. Following the increase in GNSS observations, additional improvements were made in the MIT Haystack GNSS data processing algorithms, allowing for finer grid spacing of the output TEC data. Merging data sets also increased sensitivity. Scintillation data from several GNSS receivers have been overlaid on top of all-sky camera images showing evidence of aurora. These data sets have been merged with the measured background TEC to monitor the development both medium and fine-scale TEC gradients. Data from multiple geomagnetic storms and auroral events in this solar cycle will be presented.

  2. Frontal Oscillatory Dynamics Predict Feedback Learning and Action Adjustment

    ERIC Educational Resources Information Center

    van de Vijver, Irene; Ridderinkhof, K. Richard; Cohen, Michael X.

    2011-01-01

    Frontal oscillatory dynamics in the theta (4-8 Hz) and beta (20-30 Hz) frequency bands have been implicated in cognitive control processes. Here we investigated the changes in coordinated activity within and between frontal brain areas during feedback-based response learning. In a time estimation task, participants learned to press a button after…

  3. Frontal Oscillatory Dynamics Predict Feedback Learning and Action Adjustment

    ERIC Educational Resources Information Center

    van de Vijver, Irene; Ridderinkhof, K. Richard; Cohen, Michael X.

    2011-01-01

    Frontal oscillatory dynamics in the theta (4-8 Hz) and beta (20-30 Hz) frequency bands have been implicated in cognitive control processes. Here we investigated the changes in coordinated activity within and between frontal brain areas during feedback-based response learning. In a time estimation task, participants learned to press a button after…

  4. A nanobuffer reporter library for fine-scale imaging and perturbation of endocytic organelles | Office of Cancer Genomics

    Cancer.gov

    Endosomes, lysosomes and related catabolic organelles are a dynamic continuum of vacuolar structures that impact a number of cell physiological processes such as protein/lipid metabolism, nutrient sensing and cell survival. Here we develop a library of ultra-pH-sensitive fluorescent nanoparticles with chemical properties that allow fine-scale, multiplexed, spatio-temporal perturbation and quantification of catabolic organelle maturation at single organelle resolution to support quantitative investigation of these processes in living cells.

  5. Fine-Scale Spatial Variability of Precipitation, Soil, and Plant Water Isotopes

    NASA Astrophysics Data System (ADS)

    Goldsmith, G. R.; Braun, S.; Romero, C.; Engbersen, N.; Gessler, A.; Siegwolf, R. T.; Schmid, L.

    2015-12-01

    constrain the variability within different water sources across space (e.g. when vizualized as isoscapes), as well as the extent of fractionation among those sources as water moves through the critical zone. In doing so, we also provide insight into how environment shapes this fine-scale variation in order to inform future applications of water isotopes.

  6. The fine-scale spatial distribution of surface moisture content in Canadian and Irish peatlands

    NASA Astrophysics Data System (ADS)

    Prat, Nuria; Thompson, Daniel; Turetsky, Merritt; Rein, Guillermo; Hadden, Rory; Belcher, Claire; Yearsley, Jon

    2014-05-01

    Natural peatlands are characterised for having a water-table close to the surface, saturating all the layers of the peat profile. In contrast, in drained peatlands there is a decrease of the water-table position and a subsequent drop of moisture content of the superficial layers. When the peat reaches levels of moisture content below 125% (in a dry weight basis) it becomes more vulnerable to burn in a smouldering fire. While the moisture distribution through the vertical peat profile has been well studied, there is little research looking at how the moisture content is spatially distributed horizontally. There are even less studies analysing the variability of physical properties of the peat in a fine scale. In this study, we investigated the spatial distribution of moisture content, bulk density and vegetation in the superficial layers of two peatlands. Samples from a Canadian old undisturbed peatland (Burned Crow Century, AB, Canada) were taken during the summer 2013 and from a drained Irish peatland (Wicklow Mountains National Park, Ireland) were taken during the autumn 2013. We estimate spatial distribution and scale of variability of vegetation and peat physical properties such as moisture content and bulk density. In the Canadian samples we found a significant association between vegetation types and moisture content and bulk density of the peat. While for the Irish peatland there is only association between vegetation and bulk density of the peat, as the moisture content is more homogeneous through all the vegetation types. For both datasets, the scale of spatial autocorrelation is up to 50cm in peat physical properties, which is consistent with the spatial scale of the hummock-hollow microtopography. The variables in our analysis have a direct effect on the propagation of the smouldering fire in peatlands, for that reason a better knowledge of the scale and spatial variability of the peat properties can help regulating water-table levels in certain local

  7. Factors driving species assemblage in Mediterranean soil seed banks: from the large to the fine scale.

    PubMed

    Peralta, Ana María López; Sánchez, Ana María; Luzuriaga, Arantzazu L; Escudero, Adrián

    2016-06-01

    BSC cover is low suggest that BSCs promote a fine scale niche differentiation in the soil seed bank and thereby potentially enhance species coexistence and high species diversity in these communities. © The Author 2016. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  8. Fine-scale structure of the mid-mantle characterised by global stacks of PP precursors

    NASA Astrophysics Data System (ADS)

    Bentham, H. L. M.; Rost, S.; Thorne, M. S.

    2017-08-01

    Subduction zones are likely a major source of compositional heterogeneities in the mantle, which may preserve a record of the subduction history and mantle convection processes. The fine-scale structure associated with mantle heterogeneities can be studied using the scattered seismic wavefield that arrives as coda to or as energy preceding many body wave arrivals. In this study we analyse precursors to PP by creating stacks recorded at globally distributed stations. We create stacks aligned on the PP arrival in 5° distance bins (with range 70-120°) from 600 earthquakes recorded at 193 stations stacking a total of 7320 seismic records. As the energy trailing the direct P arrival, the P coda, interferes with the PP precursors, we suppress the P coda by subtracting a best fitting exponential curve to this energy. The resultant stacks show that PP precursors related to scattering from heterogeneities in the mantle are present for all distances. Lateral variations are explored by producing two regional stacks across the Atlantic and Pacific hemispheres, but we find only negligible differences in the precursory signature between these two regions. The similarity of these two regions suggests that well mixed subducted material can survive at upper and mid-mantle depth. To describe the scattered wavefield in the mantle, we compare the global stacks to synthetic seismograms generated using a Monte Carlo phonon scattering technique. We propose a best-fitting layered heterogeneity model, BRT2017, characterised by a three layer mantle with a background heterogeneity strength (ɛ = 0.8%) and a depth-interval of increased heterogeneity strength (ɛ = 1%) between 1000 km and 1800 km. The scalelength of heterogeneity is found to be 8 km throughout the mantle. Since mantle heterogeneity of 8 km scale may be linked to subducted oceanic crust, the detection of increased heterogeneity at mid-mantle depths could be associated with stalled slabs due to increases in viscosity

  9. Factors driving species assemblage in Mediterranean soil seed banks: from the large to the fine scale

    PubMed Central

    Peralta, Ana María López; Sánchez, Ana María; Luzuriaga, Arantzazu L.; Escudero, Adrián

    2016-01-01

    . Changes in species composition and enrichment when the BSC cover is low suggest that BSCs promote a fine scale niche differentiation in the soil seed bank and thereby potentially enhance species coexistence and high species diversity in these communities. PMID:27085181

  10. Fine-scale differences in diel activity among nocturnal freshwater planarias (Platyhelminthes: Tricladida)

    PubMed Central

    2011-01-01

    photonegative characteristics. The fine-scale differences in diel behavior among these three triclad species may not be sufficient to allow coexistence in the wild, with the nonnative D. tigrina eventually displacing D. polychroa and P. tenuis in many European waters. The link between planarian diel rhythms and ecological characteristics are worth of further, detailed investigation. PMID:21477354

  11. Fine-scale differences in diel activity among nocturnal freshwater planarias (Platyhelminthes: Tricladida).

    PubMed

    Lombardo, Paola; Giustini, Marco; Miccoli, Francesco Paolo; Cicolani, Bruno

    2011-04-10

    Although most freshwater planarias are well known photonegative organisms, their diel rhythms have never been quantified. Differences in daily activity rhythms may be particularly important for temperate-climate, freshwater planarias, which tend to overlap considerably in spatial distribution and trophic requirements. Activity of stress-free, individually tested young adults of three common planarian species was recorded at 3-h intervals in a 10-d experiment under natural sunlight and photoperiod during autumnal equinox (D:L ~12:12). Individual activity status was averaged over the 10-d experiment, each tested individual thus serving as a true replicate. Twelve individuals per species were tested. Food was provided every 36 h, resulting in alternating day- and nighttime feeding events. Activity during the first post-feeding h was recorded and analyzed separately. Statistical procedures included ANOVAs, correlations, and second-order analyses of angles. Dugesia (= Girardia) tigrina Girard 1850 exhibited clear nocturnal behavior, Dugesia (= Schmidtea) polychroa Schmidt 1861 was predominantly but not exclusively nocturnal, and Polycelis tenuis Ijima 1884 was relatively more active from midnight through noon. Species-specific activity peaks were statistically similar, with peaks at dawn for P. tenuis and just before midnight for the two dugesiids; however, D. tigrina was comparatively more active in the early night hours, while D. polychroa was more active than D. tigrina during daytime. D. tigrina also responded less readily to daytime food addition. P. tenuis remained poorly active and unresponsive throughout the experiment. Individual variability in diel behavior was highest for D. polychroa and lowest for D. tigrina. P. tenuis's general low degree of activity and late activity peak in the experiment may be related to a strong reliance on external stimuli. The tested species are mainly nocturnal, consistent with their photonegative characteristics. The fine-scale

  12. Fine-scale spatial variation in plant species richness and its relationship to environmental conditions in coastal marshlands

    USGS Publications Warehouse

    Mancera, J.E.; Meche, G.C.; Cardona-Olarte, P.P.; Castaneda-Moya, E.; Chiasson, R.L.; Geddes, N.A.; Schile, L.M.; Wang, H.G.; Guntenspergen, G.R.; Grace, J.B.

    2005-01-01

    Previous studies have shown that variations in environmental conditions play a major role in explaining variations in plant species richness at community and landscape scales. In this study, we considered the degree to which fine-scale spatial variations in richness could be related to fine-scale variations in abiotic and biotic factors. To examine spatial variation in richness, grids of 1 m(2) plots were laid out at five sites within a coastal riverine wetland landscape. At each site, a 5 x 7 array of plots was established adjacent to the river's edge with plots one meter apart. In addition to the estimation of species richness, environmental measurements included sediment salinity, plot microelevation, percent of plot recently disturbed, and estimated community biomass. Our analysis strategy was to combine the use of structural equation modeling (path modeling) with an assessment of spatial association. Mantel's tests revealed significant spatial autocorrelation in species richness at four of the five sites sampled, indicating that richness in a plot correlated with the richness of nearby plots. We subsequently considered the degree to which spatial autocorrelations in richness could be explained by spatial autocorrelations in environmental conditions. Once data were corrected for environmental correlations, spatial autocorrelation in residual species richness could not be detected at any site. Based on these results, we conclude that in this coastal wetland, there appears to be a fine-scale mapping of diversity to microgradients in environmental conditions.

  13. Demonstrating the Uneven Importance of Fine-Scale Forest Structure on Snow Distributions using High Resolution Modeling

    NASA Astrophysics Data System (ADS)

    Broxton, P. D.; Harpold, A. A.; van Leeuwen, W.; Biederman, J. A.

    2016-12-01

    Quantifying the amount of snow in forested mountainous environments, as well as how it may change due to warming and forest disturbance, is critical given its importance for water supply and ecosystem health. Forest canopies affect snow accumulation and ablation in ways that are difficult to observe and model. Furthermore, fine-scale forest structure can accentuate or diminish the effects of forest-snow interactions. Despite decades of research demonstrating the importance of fine-scale forest structure (e.g. canopy edges and gaps) on snow, we still lack a comprehensive understanding of where and when forest structure has the largest impact on snowpack mass and energy budgets. Here, we use a hyper-resolution (1 meter spatial resolution) mass and energy balance snow model called the Snow Physics and Laser Mapping (SnowPALM) model along with LIDAR-derived forest structure to determine where spatial variability of fine-scale forest structure has the largest influence on large scale mass and energy budgets. SnowPALM was set up and calibrated at sites representing diverse climates in New Mexico, Arizona, and California. Then, we compared simulations at different model resolutions (i.e. 1, 10, and 100 m) to elucidate the effects of including versus not including information about fine scale canopy structure. These experiments were repeated for different prescribed topographies (i.e. flat, 30% slope north, and south-facing) at each site. Higher resolution simulations had more snow at lower canopy cover, with the opposite being true at high canopy cover. Furthermore, there is considerable scatter, indicating that different canopy arrangements can lead to different amounts of snow, even when the overall canopy coverage is the same. This modeling is contributing to the development of a high resolution machine learning algorithm called the Snow Water Artificial Network (SWANN) model to generate predictions of snow distributions over much larger domains, which has implications

  14. Oscillatory growth for twisting crystals.

    PubMed

    Ibaraki, Shunsuke; Ise, Ryuta; Ishimori, Koichiro; Oaki, Yuya; Sazaki, Gen; Yokoyama, Etsuro; Tsukamoto, Katsuo; Imai, Hiroaki

    2015-05-18

    We demonstrate the oscillatory phenomenon for the twisting growth of a triclinic crystal through in situ observation of the concentration field around the growing tip of a needle by high-resolution phase-shift interferometry.

  15. Fine-scale ignimbrite morphology revealed in LiDAR at Crater Lake, OR

    NASA Astrophysics Data System (ADS)

    Robinson, J. E.; Bacon, C. R.; Wright, H. M.

    2011-12-01

    Mount Mazama erupted ~7,700 years ago resulting in the collapse of Crater Lake caldera, ash fall across the Pacific Northwest, and emplacement of compositionally zoned ignimbrite. Early climactic ignimbrite contains uniform rhyodacitic pumice and traveled far from the vent, whereas late, less mobile ignimbrite is dominated by crystal-rich andesitic scoria and mafic crystal mush. Funded by the USGS, NPS, and FHWA, the DOGAMI-led Oregon LiDAR Consortium contracted with Watershed Services to collect ~800 km2 of LiDAR over Crater Lake National Park from Aug 2010 to Sept 2010. Ground laser returns have an average density of 1.63 returns/m2 over the heavily forested area of interest. The data have a lateral RMSE and vertical accuracy of 0.05 m. A bare earth terrain model allows a virtual removal of the forest, revealing fine-scale surface morphology, notably in the climactic ignimbrite. Secondary pyroclastic flows, explosion craters, erosion by water, and compaction-related deformation modified the originally smooth ignimbrite surface. Distinct pyroclastic flow fronts are evident in the LiDAR in Annie Creek valley. Leveed flows stand approximately 5 m above the lower ignimbrite surface, and individual toes are about 1-2 m high. Preliminary field checking indicates that rhyodacitic pumice dominates the lower ignimbrite surface, but the leveed flows are a subequal mix of locally oxidized rhyodacitic pumice and andesitic scoria. We hypothesize that these deposits were secondary pyroclastic flows formed by gravitational failure of late ignimbrite. In the Castle Creek valley, is a 2-meter collapse scarp that may have spawned a small secondary pyroclastic flow; several such headwall scarps are present in Sand Creek valley. Differential compaction features are common in many thick ignimbrites. We suggest this caused the deformation of the ignimbrite apparent in the LiDAR. In Annie Creek valley are a series of flow parallel asymmetric ridges, with shallower slopes toward the

  16. Solar fine scale structures in the corona, transition region, and lower atmosphere

    NASA Technical Reports Server (NTRS)

    Moses, Dan; Cook, J. W.; Bartoe, J. -D. F.; Brueckner, G. E.; Dere, K. P.; Webb, D. F.; Davis, J. M.; Harvey, J. W.; Realy, F.; Martin, S. F.

    1994-01-01

    The American Science and Engineering Soft X-ray Imaging Payload and the Naval Research Laboratory High Resolution Telescope and Spectrograph (HRTS) were launched from White Sands on 1987 December 11 in coordinated sounding rocket flights. The goal was to investigate the correspondence of fine-scale structures from different temperature regimes in the solar atmosphere, and particularly the relationship between X-ray bright points (XBPs) and transition region explosive events. We present results of the analysis of co-aligned X-ray images, maps of sites of transition region explosive events observed in C IV 10(exp 5), HRTS 1600 A spectroheliograms of the T(sub min) region, and ground-based magnetogram and He I 10830 A images. We examined the relationship of He I 10830 A dark features and evolving magnetic features which correspond to XBPs. We note a frequent double ribbon pattern of the He I dark feature counterparts to XBPs. We discuss an analysis of the relationship of XBPs to evolving magnetic features by Webb et al., which shows that converging magnetic features of opposite polarity are the most significant magnetic field counterparts to XBPs. The magnetic bipolar features associated with XBPs appear as prominent network elements in chromospheric and transition region images. The features in C IV observations corresponding to XBP sites are in general bright, larger scale (approximately 10 arcsec) regions of complex velocity fields of order 40 km/s, which is typical of brighter C IV network elements. These C IV features do not reach the approximately 100 km/s velocities seen in the C IV explosive events. Also, there are many similar C IV bright network features without a corresponding XBP in the X-ray image. The transition region explosive events do not correspond directly to XBPs. The explosive events appear to be concentrated in the quiet Sun at the edges of strong network, or within weaker field strength network regions. We find a greater number of C IV events

  17. Reflectance anisotropy for characterising fine-scale changes in soil surface condition across different soil types

    NASA Astrophysics Data System (ADS)

    Croft, Holly; Anderson, Karen; Kuhn, Nikolaus J.

    2010-05-01

    Soils can experience rapid structural degradation in response to land cover changes, resulting in a reduction in soil productivity, an increased susceptibility to erosion and increased release of greenhouse gases. Soil surface roughness at the centimetre scale plays a fundamental role in affecting soil erosion and surface runoff pathways. A decline in surface roughness can also be used to infer soil degradation as soil aggregates are broken down through raindrop impact. However, due to the time and resources involved in using traditional field sampling techniques, there is a lack of spatially-distributed information on soil surface condition. Remotely sensed data can provide a cost-effective means of monitoring changes in soil surface condition over broad spatial extents. Furthermore, a growing recognition into the importance of the directional reflectance domain has led to an increasing number of satellites with multiple view angle (MVA) capabilities (e.g. MISR, CHRIS on Proba). This is potentially useful for monitoring soil degradation and susceptibility to erosion because changes in soil surface roughness, associated with the breakdown of macro-aggregates, have a measurable effect on directional reflectance factors. Consequently, field and laboratory data are required for an empirical understanding of soil directional reflectance characteristics, underpinning subsequent model development. This study assessed the extent to which a hyperspectral MVA approach (350-2500 nm) could detect fine-scale changes in soil crusting states across five different soil types. A series of soil crusting states were produced for all five soil types, using an artificial rainfall simulator. The controlled conditions allowed the production of a series of stages in the soil crusting process; showing progressively declining surface roughness values. Each soil state was then spatially characterised, using a laboratory laser device at 2 mm sample spacing, over a 10 x 10 cm area. Laser data

  18. Fine-scale spatial and interannual cadmium isotope variability in the subarctic northeast Pacific

    NASA Astrophysics Data System (ADS)

    Janssen, D. J.; Abouchami, W.; Galer, S. J. G.; Cullen, J. T.

    2017-08-01

    that cannot be explained by a closed-system Rayleigh model. These results correspond with a warm water surface anomaly found along Line P in 2014 and demonstrate that there is interannual variability in the biogeochemical cycling of Cd and its isotopes in the subarctic North Pacific. In contrast to other ocean basins where vertical variability in ɛ 112 / 110Cd is observed at depth, deep and intermediate waters in the North Pacific have a near-uniform ɛ 112 / 110Cd value (mean of 1.14 ± 0.37, n = 43, 2SD) representative of nearly all samples at or below 1000 m depth. Imprinted upon this nearly homogeneous intermediate and deep North Pacific ɛ 112 / 110Cd signature are fine-scale spatial trends, with heavier values observed toward the coastal end of Line P than the oceanic end at intermediate depths, and with slightly heavier values in subtropical North Pacific deep water compared to the subarctic North Pacific. The nearly constant Cd isotopic composition of North Pacific deep waters is consistent with the inflow of Circumpolar Deep Water at depth in the Pacific basin, along with deep remineralization, and supports the potential of ɛ 112 / 110Cd as a tracer of global deepwater circulation.

  19. Magnesium content within the skeletal architecture of the coral Montastraea faveolata: locations of brucite precipitation and implications to fine-scale data fluctuations

    USGS Publications Warehouse

    Buster, N.A.; Holmes, C.W.

    2006-01-01

    Small portions of coral cores were analyzed using a high-resolution laser ablation inductively coupled plasma mass spectrometer (LA ICP-MS) to determine the geochemical signatures within and among specific skeletal structures in the large framework coral, Montastraea faveolata. Vertical transects were sampled along three parallel skeletal structures: endothecal (septal flank), corallite wall, and exothecal (costal flank) areas. The results demonstrate that trace element levels varied among the three structures. Magnesium (Mg) varied among adjacent structures and was most abundant within the exothecal portion of the skeleton. Scanning electron microscopy (SEM) revealed the presence of hexagonal crystals forming thick discs, pairs or doublets of individual crystals, and rosettes in several samples. High Mg within these crystals was confirmed with energy dispersive spectroscopy (EDS), infrared spectrometry, and LA ICP-MS. The chemical composition is consistent with the mineral brucite [Mg(OH2)]. These crystals are located exclusively in the exothecal area of the skeleton, are often associated with green endolithic algae, and are commonly associated with increased Mg levels found in the adjacent corallite walls. Although scattered throughout the exothecal, the brucite crystals are concentrated within green bands where levels of Mg increase substantially relative to other portions of the skeleton. The presence and locations of high-Mg crystals may explain the fine-scale fluctuations in Mg data researchers have been questioning for years.

  20. Fine-scale genetic assessment of sex-specific dispersal patterns in a multilevel primate society.

    PubMed

    Städele, Veronika; Van Doren, Vanessa; Pines, Mathew; Swedell, Larissa; Vigilant, Linda

    2015-01-01

    Like humans, hamadryas baboons (Papio hamadryas) are unusual among primates in having a multilevel social system and stable pair bonds, and are thus a useful model for the evolution of human sociality. While the kinship structure and sex-biased dispersal patterns that underlie human social organization have been extensively elucidated, the impact of these factors on the social system of hamadryas baboons is currently unclear. Here we use genetic analysis of individuals to elucidate the patterns of male and female dispersal across multiple levels of society in a wild population of hamadryas baboons. We characterized 244 members of five hamadryas bands at Filoha, Ethiopia by genotyping one Y-linked and 23 autosomal microsatellite loci and sequencing part of the mitochondrial hypervariable control region I. We found both male and female dispersal to be limited at the level of the band, with more movement of females than males among bands. By integrating long-term behavioral data for Band 1, we also found evidence for male and female philopatry at the clan level. We speculate that male philopatry at the clan level and female dispersal across one-male units and clans may enable both kin-based cooperation among males and the maintenance of kin bonds among females after dispersal. This would mean that, as in humans, kin bonds within both sexes are a core feature of the hamadryas social system, thus contributing to our understanding of the evolution of social organization in humans. Copyright © 2014 Elsevier Ltd. All rights reserved.

  1. The slowed brain: cortical oscillatory activity in hepatic encephalopathy.

    PubMed

    Butz, Markus; May, Elisabeth S; Häussinger, Dieter; Schnitzler, Alfons

    2013-08-15

    Oscillatory activity of the human brain has received growing interest as a key mechanism of large-scale integration across different brain regions. Besides a crucial role of oscillatory activity in the emergence of other neurological and psychiatric diseases, recent evidence indicates a key role in the pathophysiology of hepatic encephalopathy (HE). This review summarizes the current knowledge on pathological alterations of oscillatory brain activity in association with liver dysfunction and HE in the context of spontaneous brain activity, motor symptoms, sensory processing, and attention. The existing literature demonstrates a prominent slowing of the frequency of oscillatory activity as shown for spontaneous brain activity at rest, with respect to deficits of motor behavior and motor symptoms, and in the context of visual attention processes. The observed slowing extends across different subsystems of the brain and has been confirmed across different frequency bands, providing evidence for ubiquitous changes of oscillatory activity in HE. For example, the frequency of cortico-muscular coherence in HE patients appears at the frequency of the mini-asterixis (⩽12Hz), while cirrhotics without overt signs of HE show coherence similar to healthy subjects, i.e. at 13-30Hz. Interestingly, the so-called critical flicker frequency (CFF) as a measure of the processing of an oscillating visual stimulus has emerged as a useful tool to quantify HE disease severity, correlating with behavioral and neurophysiological alterations. Moreover, the CFF reliably distinguishes patients with manifest HE from cirrhotics without any signs of HE and healthy controls using a cut-off frequency of 39Hz. In conclusion, oscillatory activity is globally slowed in HE in close association with HE symptoms and disease severity. Although the underlying causal mechanisms are not yet understood, these results indicate that pathological changes of oscillatory activity play an important role in the

  2. Spatial and seasonal patterns of fine-scale to mesoscale upper ocean dynamics in an Eastern Boundary Current System

    NASA Astrophysics Data System (ADS)

    Grados, Daniel; Bertrand, Arnaud; Colas, François; Echevin, Vincent; Chaigneau, Alexis; Gutiérrez, Dimitri; Vargas, Gary; Fablet, Ronan

    2016-03-01

    The physical forcing of the ocean surface includes a variety of energetic processes, ranging from internal wave (IW) to submesoscale and mesoscale, associated with characteristic horizontal scales. While the description of mesoscale ocean dynamics has greatly benefited from the availability of satellite data, observations of finer scale patterns remain scarce. Recent studies showed that the vertical displacements of the oxycline depth, which separates the well-mixed oxygenated surface layer from the less oxygenated deeper ocean, estimated by acoustics, provide a robust proxy of isopycnal displacements over a wide range of horizontal scales. Using a high-resolution and wide-range acoustic data set in the Northern Humboldt Current System (NHCS) off Peru, the spatial and temporal patterns of fine-scale-to-mesoscale upper ocean dynamics are investigated. The spectral content of oxycline/pycnocline profiles presents patterns characteristic of turbulent flows, from the mesoscale to the fine scale, and an energization at the IW scale (2 km-200 m). On the basis of a typology performed on 35,000 structures we characterized six classes of physical structures according to their shape and scale range. The analysis reveals the existence of distinct features for the fine-scale range below ∼2-3 km, and clearly indicates the existence of intense IW and submesoscale activity over the entire NHCS region. Structures at scales smaller than ∼2 km were more numerous and energetic in spring than in summer. Their spatiotemporal variability supports the interpretation that these processes likely relate to IW generation by interactions between tidal flows, stratification and the continental slope. Given the impact of the physical forcing on the biogeochemical and ecological dynamics in EBUS, these processes should be further considered in future ecosystem studies based on observations and models. The intensification of upper ocean stratification resulting from climate change makes such

  3. Green light: gross primary production influences seasonal stream N export by controlling fine-scale N dynamics.

    PubMed

    Lupon, Anna; Martí, Eugènia; Sabater, Francesc; Bernal, Susana

    2016-01-01

    Monitoring nutrient concentrations at fine-scale temporal resolution contributes to a better understanding of nutrient cycling in stream ecosystems. However, the mechanisms underlying fine-scale nutrient dynamics and its implications for budget catchent fluxes are still poorly understood. To gain understanding of patterns and controls of fine-scale stream nitrogen (N) dynamics and to assess how they affect hydrological N fluxes, we explored diel variation in stream nitrate (NO3-) concentration along a headwater stream with increasing riparian area and channel width. At the downstream site, the highest day-night variations occurred in early spring, when stream NO3- concentrations were 13% higher at night than at daytime. Such day-night variations were strongly related to daily light inputs (R2 = 0.74) and gross primary production (GPP; R2 = 0.74), and they showed an excellent fit with day-night NO- variations predicted from GPP (R2 = 0.85). These results suggest that diel fluctuations in stream NO3- concentration were mainly driven by photoautotrophic N uptake. Terrestrial influences were discarded because no simultaneous diel variations in stream discharge, riparian groundwater level, or riparian solute concentration were observed. In contrast to the downstream site, no diel variations in NO3- concentration occurred at the upstream site, likely because water temperature was colder (10 degrees C vs. 12 degrees C) and light availability was lower (4 vs. 9 mol x m(-2) x d(-1)). Although daily GPP was between 10- and 100-fold lower than daily respiration, photoautotrophic N uptake contributed to a 10% reduction in spring NO3- loads at the downstream site. Our study clearly shows that the activity of photoautotrophs can substantially change over time and along the stream continuum in response to key environmental drivers such as light and temperature, and further, that its capacity to regulate diel and seasonal N fluxes can be important even in low-productivity streams.

  4. Fine-scale genetic population structure in a mobile marine mammal: inshore bottlenose dolphins in Moreton Bay, Australia.

    PubMed

    Ansmann, Ina C; Parra, Guido J; Lanyon, Janet M; Seddon, Jennifer M

    2012-09-01

    Highly mobile marine species in areas with no obvious geographic barriers are expected to show low levels of genetic differentiation. However, small-scale variation in habitat may lead to resource polymorphisms and drive local differentiation by adaptive divergence. Using nuclear microsatellite genotyping at 20 loci, and mitochondrial control region sequencing, we investigated fine-scale population structuring of inshore bottlenose dolphins (Tursiops aduncus) inhabiting a range of habitats in and around Moreton Bay, Australia. Bayesian structure analysis identified two genetic clusters within Moreton Bay, with evidence of admixture between them (F(ST) = 0.05, P = 0.001). There was only weak isolation by distance but one cluster of dolphins was more likely to be found in shallow southern areas and the other in the deeper waters of the central northern bay. In further analysis removing admixed individuals, southern dolphins appeared genetically restricted with lower levels of variation (AR = 3.252, π = 0.003) and high mean relatedness (r = 0.239) between individuals. In contrast, northern dolphins were more diverse (AR = 4.850, π = 0.009) and were mixing with a group of dolphins outside the bay (microsatellite-based STRUCTURE analysis), which appears to have historically been distinct from the bay dolphins (mtDNA Φ(ST) = 0.272, P < 0.001). This study demonstrates the ability of genetic techniques to expose fine-scale patterns of population structure and explore their origins and mechanisms. A complex variety of inter-related factors including local habitat variation, differential resource use, social behaviour and learning, and anthropogenic disturbances are likely to have played a role in driving fine-scale population structure among bottlenose dolphins in Moreton Bay.

  5. Fine-Scale Bacterial Beta Diversity within a Complex Ecosystem (Zodletone Spring, OK, USA): The Role of the Rare Biosphere

    PubMed Central

    Youssef, Noha H.; Couger, M. B.; Elshahed, Mostafa S.

    2010-01-01

    Background The adaptation of pyrosequencing technologies for use in culture-independent diversity surveys allowed for deeper sampling of ecosystems of interest. One extremely well suited area of interest for pyrosequencing-based diversity surveys that has received surprisingly little attention so far, is examining fine scale (e.g. micrometer to millimeter) beta diversity in complex microbial ecosystems. Methodology/Principal Findings We examined the patterns of fine scale Beta diversity in four adjacent sediment samples (1mm apart) from the source of an anaerobic sulfide and sulfur rich spring (Zodletone spring) in southwestern Oklahoma, USA. Using pyrosequencing, a total of 292,130 16S rRNA gene sequences were obtained. The beta diversity patterns within the four datasets were examined using various qualitative and quantitative similarity indices. Low levels of Beta diversity (high similarity indices) were observed between the four samples at the phylum-level. However, at a putative species (OTU0.03) level, higher levels of beta diversity (lower similarity indices) were observed. Further examination of beta diversity patterns within dominant and rare members of the community indicated that at the putative species level, beta diversity is much higher within rare members of the community. Finally, sub-classification of rare members of Zodletone spring community based on patterns of novelty and uniqueness, and further examination of fine scale beta diversity of each of these subgroups indicated that members of the community that are unique, but non novel showed the highest beta diversity within these subgroups of the rare biosphere. Conclusions/Significance The results demonstrate the occurrence of high inter-sample diversity within seemingly identical samples from a complex habitat. We reason that such unexpected diversity should be taken into consideration when exploring gamma diversity of various ecosystems, as well as planning for sequencing-intensive metagenomic

  6. Temperate rain forest species partition fine-scale gradients in light availability based on their leaf mass per area (LMA).

    PubMed

    Fajardo, Alex; Siefert, Andrew

    2016-12-01

    Ecologists are increasingly using plant functional traits to predict community assembly, but few studies have linked functional traits to species' responses to fine-scale resource gradients. In this study, it was tested whether saplings of woody species partition fine-scale gradients in light availability based on their leaf mass per area (LMA) in three temperate rain forests and one Mediterranean forest in southern Chile. LMA was measured under field conditions of all woody species contained in approx. 60 plots of 2 m(2) in each site, and light availability, computed as the gap light index (GLI), was determined. For each site, species' pairwise differences in mean LMA (Δ LMA) and abundance-weighted mean GLI (Δ light response) of 2 m(2) plots were calculated and it was tested whether they were positively related using Mantel tests, i.e. if species with different LMA values differed in their response to light availability. Additionally linear models were fitted to the relationship between plot-level mean LMA and GLI across plots for each site. A positive and significant relationship was found between species' pairwise differences in mean LMA and differences in light response across species for all temperate rain forests, but not for the Mediterranean forest. The results also indicated a significant positive interspecific link between LMA and light availability for all forests. This is in contrast to what is traditionally reported and to expectations from the leaf economics spectrum. In environments subjected to light limitation, interspecific differences in a leaf trait (LMA) can explain the fine-scale partitioning of light availability gradients by woody plant species. This niche partitioning potentially facilitates species coexistence at the within-community level. The high frequency of evergreen shade-intolerant species in these forests may explain the positive correlation between light availability and LMA. © The Author 2016. Published by Oxford University

  7. Estimation of fine-scale recombination intensity variation in the white-echinus interval of D. melanogaster

    PubMed Central

    Singh, Nadia D.; Aquadro, Charles F.; Clark, Andrew G.

    2009-01-01

    Accurate assessment of local recombination rate variation is crucial for understanding the recombination process and for determining the impact of natural selection on linked sites. In Drosophila, local recombination intensity has been estimated primarily by statistical approaches, estimating the local slope of the relationship between the physical and genetic maps. However, these estimates are limited in resolution, and as a result, the physical scale at which recombination intensity varies in Drosophila is largely unknown. While there is some evidence suggesting as much as a 40-fold variation in crossover rate at a local scale in D. pseudoobscura, little is known about the fine-scale structure of recombination rate variation in D. melanogaster. Here, we experimentally examine the fine-scale distribution of crossover events in a 1.2 Mb region on the D. melanogaster X chromosome using a classic genetic mapping approach. Our results show that crossover frequency is significantly heterogeneous within this region, varying ~ 3.5 fold. Simulations suggest that this degree of heterogeneity is sufficient to affect levels of standing nucleotide diversity, although the magnitude of this effect is small. We recover no statistical association between empirical estimates of nucleotide diversity and recombination intensity, which is likely due to the limited number of loci sampled in our population genetic dataset. However, codon bias is significantly negatively correlated with fine-scale recombination intensity estimates, as expected. Our results shed light on the relevant physical scale to consider in evolutionary analyses relating to recombination rate, and highlight the motivations to increase the resolution of the recombination map in Drosophila. PMID:19504037

  8. Fine scale population genetic structure of Varroa destructor, an ectoparasitic mite of the honey bee (Apis mellifera).

    PubMed

    Dynes, Travis L; De Roode, Jacobus C; Lyons, Justine I; Berry, Jennifer A; Delaplane, Keith S; Brosi, Berry J

    2016-01-01

    Varroa destructor is an obligate ectoparasitic mite and the most important biotic threat currently facing honey bees (Apis mellifera). We used neutral microsatellites to analyze previously unreported fine scale population structure of V. destructor, a species characterized by extreme lack of genetic diversity owing to multiple bottleneck events, haplodiploidy, and primarily brother-sister matings. Our results surprisingly indicate that detectable hierarchical genetic variation exists between apiaries, between colonies within an apiary, and even within colonies. This finding of within-colony parasite diversity provides empirical evidence that the spread of V. destructor is not accomplished solely by vertical transmission but that horizontal transmission (natural or human-mediated) must occur regularly.

  9. Wavelet analysis of fine-scale structures in the Saturnian B and C rings using data from the Cassini spacecraft

    SciTech Connect

    Postnikov, E. B. Loskutov, A. Yu.

    2007-03-15

    A continuous wavelet transform with a complex Morlet basis offers an effective method for the analysis of an instant variable periodicity in the spatially inhomogeneous matter density in the radial structure of Saturn's rings. An original algorithm that reduces the integral transform to solving a Cauchy problem for a partial differential equation is used for an analysis of the images of Saturn's B and C rings, which were obtained in the second half of 2004 from the Cassini spacecraft. This paper is a continuation of our preceding study of the fine-scale structure of Saturn's rings reported in Zh. Eksp. Teor. Fiz. 128, 752 (2005) [JETP 101, 646 (2005)].

  10. Fine-scale genetic structure reflects sex-specific dispersal strategies in a population of sociable weavers (Philetairus socius).

    PubMed

    van Dijk, René E; Covas, Rita; Doutrelant, Claire; Spottiswoode, Claire N; Hatchwell, Ben J

    2015-08-01

    Dispersal is a critical driver of gene flow, with important consequences for population genetic structure, social interactions and other biological processes. Limited dispersal may result in kin-structured populations in which kin selection may operate, but it may also increase the risk of kin competition and inbreeding. Here, we use a combination of long-term field data and molecular genetics to examine dispersal patterns and their consequences for the population genetics of a highly social bird, the sociable weaver (Philetairus socius), which exhibits cooperation at various levels of sociality from nuclear family groups to its unique communal nests. Using 20 years of data, involving capture of 6508 birds and 3151 recaptures at 48 colonies, we found that both sexes exhibit philopatry and that any dispersal occurs over relatively short distances. Dispersal is female-biased, with females dispersing earlier, further, and to less closely related destination colonies than males. Genotyping data from 30 colonies showed that this pattern of dispersal is reflected by fine-scale genetic structure for both sexes, revealed by isolation by distance in terms of genetic relatedness and significant genetic variance among colonies. Both relationships were stronger among males than females. Crucially, significant relatedness extended beyond the level of the colony for both sexes. Such fine-scale population genetic structure may have played an important role in the evolution of cooperative behaviour in this species, but it may also result in a significant inbreeding risk, against which female-biased dispersal alone is unlikely to be an effective strategy.

  11. Fine-scale nutrient and carbonate system dynamics around cold-water coral reefs in the northeast Atlantic.

    PubMed

    Findlay, Helen S; Hennige, Sebastian J; Wicks, Laura C; Navas, Juan Moreno; Woodward, E Malcolm S; Roberts, J Murray

    2014-01-20

    Ocean acidification has been suggested as a serious threat to the future existence of cold-water corals (CWC). However, there are few fine-scale temporal and spatial datasets of carbonate and nutrients conditions available for these reefs, which can provide a baseline definition of extant conditions. Here we provide observational data from four different sites in the northeast Atlantic that are known habitats for CWC. These habitats differ by depth and by the nature of the coral habitat. At depths where CWC are known to occur across these sites the dissolved inorganic carbon ranged from 2088 to 2186 μmol kg(-1), alkalinity ranged from 2299 to 2346 μmol kg(-1), and aragonite Ω ranged from 1.35 to 2.44. At two sites fine-scale hydrodynamics caused increased variability in the carbonate and nutrient conditions over daily time-scales. The observed high level of variability must be taken into account when assessing CWC sensitivities to future environmental change.

  12. Flight paths of seabirds soaring over the ocean surface enable measurement of fine-scale wind speed and direction.

    PubMed

    Yonehara, Yoshinari; Goto, Yusuke; Yoda, Ken; Watanuki, Yutaka; Young, Lindsay C; Weimerskirch, Henri; Bost, Charles-André; Sato, Katsufumi

    2016-08-09

    Ocean surface winds are an essential factor in understanding the physical interactions between the atmosphere and the ocean. Surface winds measured by satellite scatterometers and buoys cover most of the global ocean; however, there are still spatial and temporal gaps and finer-scale variations of wind that may be overlooked, particularly in coastal areas. Here, we show that flight paths of soaring seabirds can be used to estimate fine-scale (every 5 min, ∼5 km) ocean surface winds. Fine-scale global positioning system (GPS) positional data revealed that soaring seabirds flew tortuously and ground speed fluctuated presumably due to tail winds and head winds. Taking advantage of the ground speed difference in relation to flight direction, we reliably estimated wind speed and direction experienced by the birds. These bird-based wind velocities were significantly correlated with wind velocities estimated by satellite-borne scatterometers. Furthermore, extensive travel distances and flight duration of the seabirds enabled a wide range of high-resolution wind observations, especially in coastal areas. Our study suggests that seabirds provide a platform from which to measure ocean surface winds, potentially complementing conventional wind measurements by covering spatial and temporal measurement gaps.

  13. Fine-scale flight strategies of gulls in urban airflows indicate risk and reward in city living.

    PubMed

    Shepard, Emily L C; Williamson, Cara; Windsor, Shane P

    2016-09-26

    Birds modulate their flight paths in relation to regional and global airflows in order to reduce their travel costs. Birds should also respond to fine-scale airflows, although the incidence and value of this remains largely unknown. We resolved the three-dimensional trajectories of gulls flying along a built-up coastline, and used computational fluid dynamic models to examine how gulls reacted to airflows around buildings. Birds systematically altered their flight trajectories with wind conditions to exploit updraughts over features as small as a row of low-rise buildings. This provides the first evidence that human activities can change patterns of space-use in flying birds by altering the profitability of the airscape. At finer scales still, gulls varied their position to select a narrow range of updraught values, rather than exploiting the strongest updraughts available, and their precise positions were consistent with a strategy to increase their velocity control in gusty conditions. Ultimately, strategies such as these could help unmanned aerial vehicles negotiate complex airflows. Overall, airflows around fine-scale features have profound implications for flight control and energy use, and consideration of this could lead to a paradigm-shift in the way ecologists view the urban environment.This article is part of the themed issue 'Moving in a moving medium: new perspectives on flight'.

  14. Landscape Management of Fire and Grazing Regimes Alters the Fine-Scale Habitat Utilisation by Feral Cats

    PubMed Central

    McGregor, Hugh W.; Legge, Sarah; Jones, Menna E.; Johnson, Christopher N.

    2014-01-01

    Intensification of fires and grazing by large herbivores has caused population declines in small vertebrates in many ecosystems worldwide. Impacts are rarely direct, and usually appear driven via indirect pathways, such as changes to predator-prey dynamics. Fire events and grazing may improve habitat and/or hunting success for the predators of small mammals, however, such impacts have not been documented. To test for such an interaction, we investigated fine-scale habitat selection by feral cats in relation to fire, grazing and small-mammal abundance. Our study was conducted in north-western Australia, where small mammal populations are sensitive to changes in fire and grazing management. We deployed GPS collars on 32 cats in landscapes with contrasting fire and grazing treatments. Fine-scale habitat selection was determined using discrete choice modelling of cat movements. We found that cats selected areas with open grass cover, including heavily-grazed areas. They strongly selected for areas recently burnt by intense fires, but only in habitats that typically support high abundance of small mammals. Intense fires and grazing by introduced herbivores created conditions that are favoured by cats, probably because their hunting success is improved. This mechanism could explain why, in northern Australia, impacts of feral cats on small mammals might have increased. Our results suggest the impact of feral cats could be reduced in most ecosystems by maximising grass cover, minimising the incidence of intense fires, and reducing grazing by large herbivores. PMID:25329902

  15. Fine-scale flight strategies of gulls in urban airflows indicate risk and reward in city living

    PubMed Central

    Shepard, Emily L. C.

    2016-01-01

    Birds modulate their flight paths in relation to regional and global airflows in order to reduce their travel costs. Birds should also respond to fine-scale airflows, although the incidence and value of this remains largely unknown. We resolved the three-dimensional trajectories of gulls flying along a built-up coastline, and used computational fluid dynamic models to examine how gulls reacted to airflows around buildings. Birds systematically altered their flight trajectories with wind conditions to exploit updraughts over features as small as a row of low-rise buildings. This provides the first evidence that human activities can change patterns of space-use in flying birds by altering the profitability of the airscape. At finer scales still, gulls varied their position to select a narrow range of updraught values, rather than exploiting the strongest updraughts available, and their precise positions were consistent with a strategy to increase their velocity control in gusty conditions. Ultimately, strategies such as these could help unmanned aerial vehicles negotiate complex airflows. Overall, airflows around fine-scale features have profound implications for flight control and energy use, and consideration of this could lead to a paradigm-shift in the way ecologists view the urban environment. This article is part of the themed issue ‘Moving in a moving medium: new perspectives on flight’. PMID:27528784

  16. Flight paths of seabirds soaring over the ocean surface enable measurement of fine-scale wind speed and direction

    PubMed Central

    Yonehara, Yoshinari; Goto, Yusuke; Yoda, Ken; Watanuki, Yutaka; Young, Lindsay C.; Weimerskirch, Henri; Bost, Charles-André; Sato, Katsufumi

    2016-01-01

    Ocean surface winds are an essential factor in understanding the physical interactions between the atmosphere and the ocean. Surface winds measured by satellite scatterometers and buoys cover most of the global ocean; however, there are still spatial and temporal gaps and finer-scale variations of wind that may be overlooked, particularly in coastal areas. Here, we show that flight paths of soaring seabirds can be used to estimate fine-scale (every 5 min, ∼5 km) ocean surface winds. Fine-scale global positioning system (GPS) positional data revealed that soaring seabirds flew tortuously and ground speed fluctuated presumably due to tail winds and head winds. Taking advantage of the ground speed difference in relation to flight direction, we reliably estimated wind speed and direction experienced by the birds. These bird-based wind velocities were significantly correlated with wind velocities estimated by satellite-borne scatterometers. Furthermore, extensive travel distances and flight duration of the seabirds enabled a wide range of high-resolution wind observations, especially in coastal areas. Our study suggests that seabirds provide a platform from which to measure ocean surface winds, potentially complementing conventional wind measurements by covering spatial and temporal measurement gaps. PMID:27457932

  17. Fine-scale ecological and economic assessment of climate change on olive in the Mediterranean Basin reveals winners and losers

    PubMed Central

    Ponti, Luigi; Gutierrez, Andrew Paul; Ruti, Paolo Michele; Dell’Aquila, Alessandro

    2014-01-01

    The Mediterranean Basin is a climate and biodiversity hot spot, and climate change threatens agro-ecosystems such as olive, an ancient drought-tolerant crop of considerable ecological and socioeconomic importance. Climate change will impact the interactions of olive and the obligate olive fruit fly (Bactrocera oleae), and alter the economics of olive culture across the Basin. We estimate the effects of climate change on the dynamics and interaction of olive and the fly using physiologically based demographic models in a geographic information system context as driven by daily climate change scenario weather. A regional climate model that includes fine-scale representation of the effects of topography and the influence of the Mediterranean Sea on regional climate was used to scale the global climate data. The system model for olive/olive fly was used as the production function in our economic analysis, replacing the commonly used production-damage control function. Climate warming will affect olive yield and fly infestation levels across the Basin, resulting in economic winners and losers at the local and regional scales. At the local scale, profitability of small olive farms in many marginal areas of Europe and elsewhere in the Basin will decrease, leading to increased abandonment. These marginal farms are critical to conserving soil, maintaining biodiversity, and reducing fire risk in these areas. Our fine-scale bioeconomic approach provides a realistic prototype for assessing climate change impacts in other Mediterranean agro-ecosystems facing extant and new invasive pests. PMID:24706833

  18. Genetic Geostatistical Framework for Spatial Analysis of Fine-Scale Genetic Heterogeneity in Modern Populations: Results from the KORA Study

    PubMed Central

    Diaz-Lacava, A. N.; Walier, M.; Holler, D.; Steffens, M.; Gieger, C.; Furlanello, C.; Lamina, C.; Wichmann, H. E.; Becker, T.

    2015-01-01

    Aiming to investigate fine-scale patterns of genetic heterogeneity in modern humans from a geographic perspective, a genetic geostatistical approach framed within a geographic information system is presented. A sample collected for prospective studies in a small area of southern Germany was analyzed. None indication of genetic heterogeneity was detected in previous analysis. Socio-demographic and genotypic data of German citizens were analyzed (212 SNPs; n = 728). Genetic heterogeneity was evaluated with observed heterozygosity (H O). Best-fitting spatial autoregressive models were identified, using socio-demographic variables as covariates. Spatial analysis included surface interpolation and geostatistics of observed and predicted patterns. Prediction accuracy was quantified. Spatial autocorrelation was detected for both socio-demographic and genetic variables. Augsburg City and eastern suburban areas showed higher H O values. The selected model gave best predictions in suburban areas. Fine-scale patterns of genetic heterogeneity were observed. In accordance to literature, more urbanized areas showed higher levels of admixture. This approach showed efficacy for detecting and analyzing subtle patterns of genetic heterogeneity within small areas. It is scalable in number of loci, even up to whole-genome analysis. It may be suggested that this approach may be applicable to investigate the underlying genetic history that is, at least partially, embedded in geographic data. PMID:26258132

  19. Dynamics of functional connectivity at high spatial resolution reveal long-range interactions and fine-scale organization.

    PubMed

    Preti, Maria Giulia; Van De Ville, Dimitri

    2017-10-06

    Dynamic functional connectivity (dFC) derived from resting-state functional magnetic resonance imaging sheds light onto moment-to-moment reconfigurations of large-scale functional brain networks. Due to computational limits, connectivity is typically computed using pre-defined atlases, a non-trivial choice that might influence results. Here, we leverage new computational methods to retrieve dFC at the voxel level in terms of dominant patterns of fluctuations, and demonstrate that this new representation is informative to derive meaningful brain parcellations, capturing both long-range interactions and fine-scale local organization. Specifically, voxelwise dFC dominant patterns were captured through eigenvector centrality followed by clustering across time/subjects to yield most representative dominant patterns (RDPs). Voxel-wise labeling according to positive/negative contributions to RDPs, led to 37 unique labels identifying strikingly symmetric dFC long-range patterns. These included 449 contiguous regions, defining a fine-scale parcellation consistent with known cortical/subcortical subdivisions. Our contribution provides an alternative to obtain a whole-brain parcellation that is for the first time driven by voxel-level dFC and bridges the gap between voxel-based approaches and graph theoretical analysis.

  20. The influence of fine-scale habitat features on regional variation in population performance of alpine White-tailed Ptarmigan

    USGS Publications Warehouse

    Fedy, B.; Martin, K.

    2011-01-01

    It is often assumed (explicitly or implicitly) that animals select habitat features to maximize fitness. However, there is often a mismatch between preferred habitats and indices of individual and population measures of performance. We examined the influence of fine-scale habitat selection on the overall population performance of the White-tailed Ptarmigan (Lagopus leucura), an alpine specialist, in two subdivided populations whose habitat patches are configured differently. The central region of Vancouver Island, Canada, has more continuous and larger habitat patches than the southern region. In 2003 and 2004, using paired logistic regression between used (n = 176) and available (n = 324) sites, we identified food availability, distance to standing water, and predator cover as preferred habitat components . We then quantified variation in population performance in the two regions in terms of sex ratio, age structure (n = 182 adults and yearlings), and reproductive success (n = 98 females) on the basis of 8 years of data (1995-1999, 2002-2004). Region strongly influenced females' breeding success, which, unsuccessful hens included, was consistently higher in the central region (n = 77 females) of the island than in the south (n = 21 females, P = 0.01). The central region also had a much higher proportion of successful hens (87%) than did the south (55%, P < 0.001). In light of our findings, we suggest that population performance is influenced by a combination of fine-scale habitat features and coarse-scale habitat configuration. ?? The Cooper Ornithological Society 2011.

  1. Fine-Scale Habitat Associations of a Terrestrial Salamander: The Role of Environmental Gradients and Implications for Population Dynamics

    PubMed Central

    Peterman, William E.; Semlitsch, Raymond D.

    2013-01-01

    Environmental gradients are instrumental in shaping the distribution and local abundance of species because at the most fundamental level, an organism’s performance is constrained by the environment it inhabits. In topographically complex landscapes, slope, aspect, and vegetative cover interact to affect solar exposure, creating temperature-moisture gradients and unique microclimates. The significance of the interaction of abiotic gradients and biotic factors such as competition, movement, or physiology has long been recognized, but the scale at which these factors vary on the landscape has generally precluded their inclusion in spatial abundance models. We used fine-scale spatial data relating to surface-soil moisture, temperature, and canopy cover to describe the spatial distribution of abundance of a terrestrial salamander, Plethodon albagula, across the landscape. Abundance was greatest in dense-canopy ravine habitats with high moisture and low solar exposure, resulting in a patchy distribution of abundance. We hypothesize that these patterns reflect the physiological constraints of Plethodontid salamanders. Furthermore, demographic cohorts were not uniformly distributed among occupied plots on the landscape. The probability of gravid female occurrence was nearly uniform among occupied plots, but juveniles were much more likely to occur on plots with lower surface temperatures. The disconnect between reproductive effort and recruitment suggests that survival differs across the landscape and that local population dynamics vary spatially. Our study demonstrates a connection between abundance, fine-scale environmental gradients, and population dynamics, providing a foundation for future research concerning movement, population connectivity, and physiology. PMID:23671586

  2. Dispersal, philopatry and intergroup relatedness: fine-scale genetic structure in the white-breasted thrasher, Ramphocinclus brachyurus.

    PubMed

    Temple, H J; Hoffman, J I; Amos, W

    2006-10-01

    Dispersal is a fundamental process influencing evolution, social behaviour, and the long-term persistence of populations. We use both observational and genetic data to investigate dispersal, kin-clustering and intergroup relatedness in the white-breasted thrasher, Ramphocinclus brachyurus, a cooperatively breeding bird that is globally endangered. Mark-resighting data suggested sex-biased dispersal, with females dispersing over greater distances while males remained philopatric. Accordingly, spatial autocorrelation analysis showed highly significant fine-scale genetic structure among males, but not among females. This fine-scale genetic structuring of the male population resulted in very high levels of relatedness between dominant males at neighbouring nests, similar to that seen within cooperative groups in many species where kin selection is cited as a cause of cooperation. By implication, between-group as well as within-group cooperation may be important, potentially creating a feedback loop in which short-distance dispersal by males leads to the formation of male kin clusters that in turn facilitate nepotistic interactions and favour further local recruitment. The strength of spatial autocorrelation, as measured by the autocorrelation coefficient, r, was approximately two to three times greater than that reported in previous studies of animals. Relatively short dispersal distances by both males and females may have a negative impact on the white-breasted thrasher's ability to colonize new areas, and may influence the long-term persistence of isolated populations. This should be taken into account when designating protected areas or selecting sites for habitat restoration.

  3. Fine-scale ecological and economic assessment of climate change on olive in the Mediterranean Basin reveals winners and losers.

    PubMed

    Ponti, Luigi; Gutierrez, Andrew Paul; Ruti, Paolo Michele; Dell'Aquila, Alessandro

    2014-04-15

    The Mediterranean Basin is a climate and biodiversity hot spot, and climate change threatens agro-ecosystems such as olive, an ancient drought-tolerant crop of considerable ecological and socioeconomic importance. Climate change will impact the interactions of olive and the obligate olive fruit fly (Bactrocera oleae), and alter the economics of olive culture across the Basin. We estimate the effects of climate change on the dynamics and interaction of olive and the fly using physiologically based demographic models in a geographic information system context as driven by daily climate change scenario weather. A regional climate model that includes fine-scale representation of the effects of topography and the influence of the Mediterranean Sea on regional climate was used to scale the global climate data. The system model for olive/olive fly was used as the production function in our economic analysis, replacing the commonly used production-damage control function. Climate warming will affect olive yield and fly infestation levels across the Basin, resulting in economic winners and losers at the local and regional scales. At the local scale, profitability of small olive farms in many marginal areas of Europe and elsewhere in the Basin will decrease, leading to increased abandonment. These marginal farms are critical to conserving soil, maintaining biodiversity, and reducing fire risk in these areas. Our fine-scale bioeconomic approach provides a realistic prototype for assessing climate change impacts in other Mediterranean agro-ecosystems facing extant and new invasive pests.

  4. Landscape management of fire and grazing regimes alters the fine-scale habitat utilisation by feral cats.

    PubMed

    McGregor, Hugh W; Legge, Sarah; Jones, Menna E; Johnson, Christopher N

    2014-01-01

    Intensification of fires and grazing by large herbivores has caused population declines in small vertebrates in many ecosystems worldwide. Impacts are rarely direct, and usually appear driven via indirect pathways, such as changes to predator-prey dynamics. Fire events and grazing may improve habitat and/or hunting success for the predators of small mammals, however, such impacts have not been documented. To test for such an interaction, we investigated fine-scale habitat selection by feral cats in relation to fire, grazing and small-mammal abundance. Our study was conducted in north-western Australia, where small mammal populations are sensitive to changes in fire and grazing management. We deployed GPS collars on 32 cats in landscapes with contrasting fire and grazing treatments. Fine-scale habitat selection was determined using discrete choice modelling of cat movements. We found that cats selected areas with open grass cover, including heavily-grazed areas. They strongly selected for areas recently burnt by intense fires, but only in habitats that typically support high abundance of small mammals. Intense fires and grazing by introduced herbivores created conditions that are favoured by cats, probably because their hunting success is improved. This mechanism could explain why, in northern Australia, impacts of feral cats on small mammals might have increased. Our results suggest the impact of feral cats could be reduced in most ecosystems by maximising grass cover, minimising the incidence of intense fires, and reducing grazing by large herbivores.

  5. Genetic Geostatistical Framework for Spatial Analysis of Fine-Scale Genetic Heterogeneity in Modern Populations: Results from the KORA Study.

    PubMed

    Diaz-Lacava, A N; Walier, M; Holler, D; Steffens, M; Gieger, C; Furlanello, C; Lamina, C; Wichmann, H E; Becker, T

    2015-01-01

    Aiming to investigate fine-scale patterns of genetic heterogeneity in modern humans from a geographic perspective, a genetic geostatistical approach framed within a geographic information system is presented. A sample collected for prospective studies in a small area of southern Germany was analyzed. None indication of genetic heterogeneity was detected in previous analysis. Socio-demographic and genotypic data of German citizens were analyzed (212 SNPs; n = 728). Genetic heterogeneity was evaluated with observed heterozygosity (H O ). Best-fitting spatial autoregressive models were identified, using socio-demographic variables as covariates. Spatial analysis included surface interpolation and geostatistics of observed and predicted patterns. Prediction accuracy was quantified. Spatial autocorrelation was detected for both socio-demographic and genetic variables. Augsburg City and eastern suburban areas showed higher H O values. The selected model gave best predictions in suburban areas. Fine-scale patterns of genetic heterogeneity were observed. In accordance to literature, more urbanized areas showed higher levels of admixture. This approach showed efficacy for detecting and analyzing subtle patterns of genetic heterogeneity within small areas. It is scalable in number of loci, even up to whole-genome analysis. It may be suggested that this approach may be applicable to investigate the underlying genetic history that is, at least partially, embedded in geographic data.

  6. Fine-scale nutrient and carbonate system dynamics around cold-water coral reefs in the northeast Atlantic

    PubMed Central

    Findlay, Helen S.; Hennige, Sebastian J.; Wicks, Laura C.; Navas, Juan Moreno; Woodward, E. Malcolm S.; Roberts, J. Murray

    2014-01-01

    Ocean acidification has been suggested as a serious threat to the future existence of cold-water corals (CWC). However, there are few fine-scale temporal and spatial datasets of carbonate and nutrients conditions available for these reefs, which can provide a baseline definition of extant conditions. Here we provide observational data from four different sites in the northeast Atlantic that are known habitats for CWC. These habitats differ by depth and by the nature of the coral habitat. At depths where CWC are known to occur across these sites the dissolved inorganic carbon ranged from 2088 to 2186 μmol kg−1, alkalinity ranged from 2299 to 2346 μmol kg−1, and aragonite Ω ranged from 1.35 to 2.44. At two sites fine-scale hydrodynamics caused increased variability in the carbonate and nutrient conditions over daily time-scales. The observed high level of variability must be taken into account when assessing CWC sensitivities to future environmental change. PMID:24441283

  7. Fine-scale spatial genetic structure and clonal distribution of the cold-water coral Lophelia pertusa

    NASA Astrophysics Data System (ADS)

    Dahl, M. P.; Pereyra, R. T.; Lundälv, T.; André, C.

    2012-12-01

    Determining the spatial genetic structure within and among cold-water coral populations is crucial to understanding population dynamics, assessing the resilience of cold-water coral communities and estimating genetic effects of habitat fragmentation for conservation. The spatial distribution of genetic diversity in natural populations depends on the species' mode of reproduction, and coral species often have a mixed strategy of sexual and asexual reproduction. We describe the clonal architecture of a cold-water coral reef and the fine-scale population genetic structure (<35 km) of five reef localities in the NE Skagerrak. This study represents the first of this type of analysis from deep waters. We used thirteen microsatellite loci to estimate gene flow and genotypic diversity and to describe the fine-scale spatial distribution of clonal individuals of Lophelia pertusa. Within-population genetic diversity was high in four of the five reef localities. These four reefs constitute a genetic cluster with asymmetric gene flow that indicates metapopulation dynamics. One locality, the Säcken reef, was genetically isolated and depauperate. Asexual reproduction was found to be a highly important mode of reproduction for L. pertusa: 35 genetic individuals were found on the largest reef, with the largest clone covering an area of nearly 300 m2.

  8. Oscillatory integration windows in neurons

    PubMed Central

    Gupta, Nitin; Singh, Swikriti Saran; Stopfer, Mark

    2016-01-01

    Oscillatory synchrony among neurons occurs in many species and brain areas, and has been proposed to help neural circuits process information. One hypothesis states that oscillatory input creates cyclic integration windows: specific times in each oscillatory cycle when postsynaptic neurons become especially responsive to inputs. With paired local field potential (LFP) and intracellular recordings and controlled stimulus manipulations we directly test this idea in the locust olfactory system. We find that inputs arriving in Kenyon cells (KCs) sum most effectively in a preferred window of the oscillation cycle. With a computational model, we show that the non-uniform structure of noise in the membrane potential helps mediate this process. Further experiments performed in vivo demonstrate that integration windows can form in the absence of inhibition and at a broad range of oscillation frequencies. Our results reveal how a fundamental coincidence-detection mechanism in a neural circuit functions to decode temporally organized spiking. PMID:27976720

  9. Oscillatory integration windows in neurons.

    PubMed

    Gupta, Nitin; Singh, Swikriti Saran; Stopfer, Mark

    2016-12-15

    Oscillatory synchrony among neurons occurs in many species and brain areas, and has been proposed to help neural circuits process information. One hypothesis states that oscillatory input creates cyclic integration windows: specific times in each oscillatory cycle when postsynaptic neurons become especially responsive to inputs. With paired local field potential (LFP) and intracellular recordings and controlled stimulus manipulations we directly test this idea in the locust olfactory system. We find that inputs arriving in Kenyon cells (KCs) sum most effectively in a preferred window of the oscillation cycle. With a computational model, we show that the non-uniform structure of noise in the membrane potential helps mediate this process. Further experiments performed in vivo demonstrate that integration windows can form in the absence of inhibition and at a broad range of oscillation frequencies. Our results reveal how a fundamental coincidence-detection mechanism in a neural circuit functions to decode temporally organized spiking.

  10. Identifying Where REDD+ Financially Out-Competes Oil Palm in Floodplain Landscapes Using a Fine-Scale Approach.

    PubMed

    Abram, Nicola K; MacMillan, Douglas C; Xofis, Panteleimon; Ancrenaz, Marc; Tzanopoulos, Joseph; Ong, Robert; Goossens, Benoit; Koh, Lian Pin; Del Valle, Christian; Peter, Lucy; Morel, Alexandra C; Lackman, Isabelle; Chung, Robin; Kler, Harjinder; Ambu, Laurentius; Baya, William; Knight, Andrew T

    2016-01-01

    Reducing Emissions from Deforestation and forest Degradation (REDD+) aims to avoid forest conversion to alternative land-uses through financial incentives. Oil-palm has high opportunity costs, which according to current literature questions the financial competitiveness of REDD+ in tropical lowlands. To understand this more, we undertook regional fine-scale and coarse-scale analyses (through carbon mapping and economic modelling) to assess the financial viability of REDD+ in safeguarding unprotected forest (30,173 ha) in the Lower Kinabatangan floodplain in Malaysian Borneo. Results estimate 4.7 million metric tons of carbon (MgC) in unprotected forest, with 64% allocated for oil-palm cultivations. Through fine-scale mapping and carbon accounting, we demonstrated that REDD+ can outcompete oil-palm in regions with low suitability, with low carbon prices and low carbon stock. In areas with medium oil-palm suitability, REDD+ could outcompete oil palm in areas with: very high carbon and lower carbon price; medium carbon price and average carbon stock; or, low carbon stock and high carbon price. Areas with high oil palm suitability, REDD+ could only outcompete with higher carbon price and higher carbon stock. In the coarse-scale model, oil-palm outcompeted REDD+ in all cases. For the fine-scale models at the landscape level, low carbon offset prices (US $3 MgCO2e) would enable REDD+ to outcompete oil-palm in 55% of the unprotected forests requiring US $27 million to secure these areas for 25 years. Higher carbon offset price (US $30 MgCO2e) would increase the competitiveness of REDD+ within the landscape but would still only capture between 69%-74% of the unprotected forest, requiring US $380-416 million in carbon financing. REDD+ has been identified as a strategy to mitigate climate change by many countries (including Malaysia). Although REDD+ in certain scenarios cannot outcompete oil palm, this research contributes to the global REDD+ debate by: highlighting REDD

  11. Identifying Where REDD+ Financially Out-Competes Oil Palm in Floodplain Landscapes Using a Fine-Scale Approach

    PubMed Central

    MacMillan, Douglas C.; Xofis, Panteleimon; Ancrenaz, Marc; Tzanopoulos, Joseph; Ong, Robert; Goossens, Benoit; Koh, Lian Pin; Del Valle, Christian; Peter, Lucy; Morel, Alexandra C.; Lackman, Isabelle; Chung, Robin; Kler, Harjinder; Ambu, Laurentius; Baya, William; Knight, Andrew T.

    2016-01-01

    Reducing Emissions from Deforestation and forest Degradation (REDD+) aims to avoid forest conversion to alternative land-uses through financial incentives. Oil-palm has high opportunity costs, which according to current literature questions the financial competitiveness of REDD+ in tropical lowlands. To understand this more, we undertook regional fine-scale and coarse-scale analyses (through carbon mapping and economic modelling) to assess the financial viability of REDD+ in safeguarding unprotected forest (30,173 ha) in the Lower Kinabatangan floodplain in Malaysian Borneo. Results estimate 4.7 million metric tons of carbon (MgC) in unprotected forest, with 64% allocated for oil-palm cultivations. Through fine-scale mapping and carbon accounting, we demonstrated that REDD+ can outcompete oil-palm in regions with low suitability, with low carbon prices and low carbon stock. In areas with medium oil-palm suitability, REDD+ could outcompete oil palm in areas with: very high carbon and lower carbon price; medium carbon price and average carbon stock; or, low carbon stock and high carbon price. Areas with high oil palm suitability, REDD+ could only outcompete with higher carbon price and higher carbon stock. In the coarse-scale model, oil-palm outcompeted REDD+ in all cases. For the fine-scale models at the landscape level, low carbon offset prices (US $3 MgCO2e) would enable REDD+ to outcompete oil-palm in 55% of the unprotected forests requiring US $27 million to secure these areas for 25 years. Higher carbon offset price (US $30 MgCO2e) would increase the competitiveness of REDD+ within the landscape but would still only capture between 69%-74% of the unprotected forest, requiring US $380–416 million in carbon financing. REDD+ has been identified as a strategy to mitigate climate change by many countries (including Malaysia). Although REDD+ in certain scenarios cannot outcompete oil palm, this research contributes to the global REDD+ debate by: highlighting REDD

  12. The fine-scale genetic structure of the two-spotted spider mite in a commercial greenhouse.

    PubMed

    Uesugi, R; Kunimoto, Y; Osakabe, Mh

    2009-02-01

    The fine-scale genetic structure of Tetranychus urticae Koch was studied to estimate local gene flow within a rose tree habitat in a commercial greenhouse using seven microsatellite markers. Two beds of rose trees with different population densities were selected and 18 consecutive quadrats of 1.2 m length were sequentially established in each bed. Heterozygote deficiency was positive within quadrats, which was most likely a result of the Wahlund effect because the mites usually form small breeding colonies. Low population density and frequent inbreeding could also accelerate genetic differentiation among the breeding colonies. A short-range (2.4-3.6 m) positive autocorrelation and clear genetic cline among quadrat populations was detected within a bed. This suggests that gene flow was limited to a short range even if population density was substantially increased. Therefore, large-scale dispersal such as aerial dispersal contributed very little to gene flow in the greenhouse.

  13. Adaptive radiation by waves of gene transfer leads to fine-scale resource partitioning in marine microbes

    PubMed Central

    Hehemann, Jan-Hendrik; Arevalo, Philip; Datta, Manoshi S.; Yu, Xiaoqian; Corzett, Christopher H.; Henschel, Andreas; Preheim, Sarah P.; Timberlake, Sonia; Alm, Eric J.; Polz, Martin F.

    2016-01-01

    Adaptive radiations are important drivers of niche filling, since they rapidly adapt a single clade of organisms to ecological opportunities. Although thought to be common for animals and plants, adaptive radiations have remained difficult to document for microbes in the wild. Here we describe a recent adaptive radiation leading to fine-scale ecophysiological differentiation in the degradation of an algal glycan in a clade of closely related marine bacteria. Horizontal gene transfer is the primary driver in the diversification of the pathway leading to several ecophysiologically differentiated Vibrionaceae populations adapted to different physical forms of alginate. Pathway architecture is predictive of function and ecology, underscoring that horizontal gene transfer without extensive regulatory changes can rapidly assemble fully functional pathways in microbes. PMID:27653556

  14. Statistical models of summer rainshowers derived from fine-scale radar observations. [for spacecraft microwave communications attenuation

    NASA Technical Reports Server (NTRS)

    Konrad, T. G.

    1978-01-01

    A statistical modeling of rain cell characteristics is presented; the modeling is based on high-resolution radar measurements of the cell structure. The analysis of the fine-scale three-dimensional structure of summer rainshowers in the mid-Atlantic region leads to statistical descriptions of the rain cells in terms of a variety of physical cell parameters. Core reflectivity profiles, contour area, and altitude extent of the cells have been determined along with the frequency of occurrence for various storm classes and categories. The statistical descriptions of the rain cells for the mid-Atlantic region were compared to descriptions for other areas, and the similarities and differences are described. Simplified models of rain cells based on the statistical descriptions are developed for the different rain categories as a function of frequency of occurrence.

  15. Fine-scale anisotropy of the cosmic microwave background in a universe dominated by cold dark matter

    NASA Technical Reports Server (NTRS)

    Vittorio, N.; Silk, J.

    1984-01-01

    The fine-scale anisotropy of the cosmic microwave background radiation has been studied in cosmological models with a scale-invariant primordial adiabatic density fluctuation spectrum dominated by cold, weakly interacting particles. Normalization of the present fluctuation spectrum to the observed galaxy distribution results in excessive temperature anisotropy when compared to a recent upper limit on 4.5 arcmin unless the density parameter exceeds 0.4. When this result is combined with the requirement that the universe be at least 13 billion years old, it is found that if the cosmological constant is zero, then the density parameter is between roughly 0.4 and 1 and the Hubble constant is between roughly 60 km/s/Mpc and 50 km/s/Mpc.

  16. Fine scale population genetic structure of Varroa destructor, an ectoparasitic mite of the honey bee (Apis mellifera)

    PubMed Central

    Dynes, Travis L.; De Roode, Jacobus C.; Lyons, Justine I.; Berry, Jennifer A.; Delaplane, Keith S.; Brosi, Berry J.

    2016-01-01

    Varroa destructor is an obligate ectoparasitic mite and the most important biotic threat currently facing honey bees (Apis mellifera). We used neutral microsatellites to analyze previously unreported fine scale population structure of V. destructor, a species characterized by extreme lack of genetic diversity owing to multiple bottleneck events, haplodiploidy, and primarily brother-sister matings. Our results surprisingly indicate that detectable hierarchical genetic variation exists between apiaries, between colonies within an apiary, and even within colonies. This finding of within-colony parasite diversity provides empirical evidence that the spread of V. destructor is not accomplished solely by vertical transmission but that horizontal transmission (natural or human-mediated) must occur regularly. PMID:27812229

  17. Fine-scale genetic variation and evolution of West Nile Virus in a transmission "hot spot" in suburban Chicago, USA.

    PubMed

    Bertolotti, Luigi; Kitron, Uriel D; Walker, Edward D; Ruiz, Marilyn O; Brawn, Jeffrey D; Loss, Scott R; Hamer, Gabriel L; Goldberg, Tony L

    2008-05-10

    Mosquitoes and birds were sampled for West Nile virus (WNV) in suburban Chicago, USA, in a "hot spot" of arboviral transmission. Viral genetic diversity within this area was similar to that within Illinois and the United States. Diversity was higher among viruses from mosquitoes than from birds, higher among viruses from birds in urban "green spaces" than from birds in residential areas, but lower among viruses from mosquitoes in green spaces than from mosquitoes in residential areas. Viral transmission was distance-limited, as evidenced by decreasing autocorrelation of WNV sequences with increasing geographic separation. The evolutionary rate of WNV within the study area between 21 July and 4 October 2005 was ten times higher than that for WNV across North America between 2002 and 2005. These results indicate that WNV transmission and evolutionary dynamics can vary seasonally and in response to fine-scale environmental conditions and landscape characteristics related to urbanization.

  18. On the fine-scale mixing in the metalimnion and the seasonal thermocline of the Leman (Lake Geneva, Switzerland)

    NASA Astrophysics Data System (ADS)

    Vecsernyes, Z.; Lemmin, U.; Graf, W. H.

    A measurement campaign was carried out from 31 Aug. to 30 Sep. 1988 in the northern part of Lake Geneva, Switzerland, in the Vidy bay about 1.3 km offshore, to investigate the fine-scale mixing phenomenon of the metalimnion and near seasonal thermocline. Current meters were placed between a depth of 5.0 and 20.0 m spaced 2.5 m apart. The observed mean currents showed a pattern of Ekman spiraling during E-going phases while the more dominant W-going ones oriented along the coast did not show any particular profile. There were two strong bise episodes in Sep. 1988. The time series analyses of temperatures of currents highlighted Poincare type internal wave activity. During strong north east oriented wind (bise) episodes the wave amplitude was strongly increased. Richardson number series pointed to mixing activity as a consequence of the second bise.

  19. Frequency-dependent oscillatory neural profiles during imitation

    PubMed Central

    Sugata, Hisato; Hirata, Masayuki; Tamura, Yuichi; Onishi, Hisao; Goto, Tetsu; Araki, Toshihiko; Yorifuji, Shiro

    2017-01-01

    Imitation is a complex process that includes higher-order cognitive and motor function. This process requires an observation-execution matching system that transforms an observed action into an identical movement. Although the low-gamma band is thought to reflect higher cognitive processes, no studies have focused on it. Here, we used magnetoencephalography (MEG) to examine the neural oscillatory changes including the low-gamma band during imitation. Twelve healthy, right-handed participants performed a finger task consisting of four conditions (imitation, execution, observation, and rest). During the imitation and execution conditions, significant event-related desynchronizations (ERDs) were observed at the left frontal, central, and parietal MEG sensors in the alpha, beta, and low-gamma bands. Functional connectivity analysis at the sensor level revealed an imitation-related connectivity between a group of frontal sensors and a group of parietal sensors in the low-gamma band. Furthermore, source reconstruction with synthetic aperture magnetometry showed significant ERDs in the low-gamma band in the left sensorimotor area and the middle frontal gyrus (MFG) during the imitation condition when compared with the other three conditions. Our results suggest that the oscillatory neural activities of the low-gamma band at the sensorimotor area and MFG play an important role in the observation-execution matching system related to imitation. PMID:28393878

  20. Frequency-dependent oscillatory neural profiles during imitation.

    PubMed

    Sugata, Hisato; Hirata, Masayuki; Tamura, Yuichi; Onishi, Hisao; Goto, Tetsu; Araki, Toshihiko; Yorifuji, Shiro

    2017-04-10

    Imitation is a complex process that includes higher-order cognitive and motor function. This process requires an observation-execution matching system that transforms an observed action into an identical movement. Although the low-gamma band is thought to reflect higher cognitive processes, no studies have focused on it. Here, we used magnetoencephalography (MEG) to examine the neural oscillatory changes including the low-gamma band during imitation. Twelve healthy, right-handed participants performed a finger task consisting of four conditions (imitation, execution, observation, and rest). During the imitation and execution conditions, significant event-related desynchronizations (ERDs) were observed at the left frontal, central, and parietal MEG sensors in the alpha, beta, and low-gamma bands. Functional connectivity analysis at the sensor level revealed an imitation-related connectivity between a group of frontal sensors and a group of parietal sensors in the low-gamma band. Furthermore, source reconstruction with synthetic aperture magnetometry showed significant ERDs in the low-gamma band in the left sensorimotor area and the middle frontal gyrus (MFG) during the imitation condition when compared with the other three conditions. Our results suggest that the oscillatory neural activities of the low-gamma band at the sensorimotor area and MFG play an important role in the observation-execution matching system related to imitation.

  1. Seasonal variation in coastal marine habitat use by the European shag: Insights from fine scale habitat selection modeling and diet

    NASA Astrophysics Data System (ADS)

    Michelot, Candice; Pinaud, David; Fortin, Matthieu; Maes, Philippe; Callard, Benjamin; Leicher, Marine; Barbraud, Christophe

    2017-07-01

    Studies of habitat selection by higher trophic level species are necessary for using top predator species as indicators of ecosystem functioning. However, contrary to terrestrial ecosystems, few habitat selection studies have been conducted at a fine scale for coastal marine top predator species, and fewer have coupled diet data with habitat selection modeling to highlight a link between prey selection and habitat use. The aim of this study was to characterize spatially and oceanographically, at a fine scale, the habitats used by the European Shag Phalacrocorax aristotelis in the Special Protection Area (SPA) of Houat-Hœdic in the Mor Braz Bay during its foraging activity. Habitat selection models were built using in situ observation data of foraging shags (transect sampling) and spatially explicit environmental data to characterize marine benthic habitats. Observations were first adjusted for detectability biases and shag abundance was subsequently spatialized. The influence of habitat variables on shag abundance was tested using Generalized Linear Models (GLMs). Diet data were finally confronted to habitat selection models. Results showed that European shags breeding in the Mor Braz Bay changed foraging habitats according to the season and to the different environmental and energetic constraints. The proportion of the main preys also varied seasonally. Rocky and coarse sand habitats were clearly preferred compared to fine or muddy sand habitats. Shags appeared to be more selective in their foraging habitats during the breeding period and the rearing of chicks, using essentially rocky areas close to the colony and consuming preferentially fish from the Labridae family and three other fish families in lower proportions. During the post-breeding period shags used a broader range of habitats and mainly consumed Gadidae. Thus, European shags seem to adjust their feeding strategy to minimize energetic costs, to avoid intra-specific competition and to maximize access

  2. Fine-scale mapping of vector habitats using very high resolution satellite imagery: a liver fluke case-study.

    PubMed

    De Roeck, Els; Van Coillie, Frieke; De Wulf, Robert; Soenen, Karen; Charlier, Johannes; Vercruysse, Jozef; Hantson, Wouter; Ducheyne, Els; Hendrickx, Guy

    2014-12-01

    The visualization of vector occurrence in space and time is an important aspect of studying vector-borne diseases. Detailed maps of possible vector habitats provide valuable information for the prediction of infection risk zones but are currently lacking for most parts of the world. Nonetheless, monitoring vector habitats from the finest scales up to farm level is of key importance to refine currently existing broad-scale infection risk models. Using Fasciola hepatica, a parasite liver fluke, as a case in point, this study illustrates the potential of very high resolution (VHR) optical satellite imagery to efficiently and semi-automatically detect detailed vector habitats. A WorldView2 satellite image capable of <5m resolution was acquired in the spring of 2013 for the area around Bruges, Belgium, a region where dairy farms suffer from liver fluke infections transmitted by freshwater snails. The vector thrives in small water bodies (SWBs), such as ponds, ditches and other humid areas consisting of open water, aquatic vegetation and/or inundated grass. These water bodies can be as small as a few m2 and are most often not present on existing land cover maps because of their small size. We present a classification procedure based on object-based image analysis (OBIA) that proved valuable to detect SWBs at a fine scale in an operational and semi-automated way. The classification results were compared to field and other reference data such as existing broad-scale maps and expert knowledge. Overall, the SWB detection accuracy reached up to 87%. The resulting fine-scale SWB map can be used as input for spatial distribution modelling of the liver fluke snail vector to enable development of improved infection risk mapping and management advice adapted to specific, local farm situations.

  3. Fine scale climatic and soil variability effects on plant species cover along the Front Range of Colorado, USA

    NASA Astrophysics Data System (ADS)

    Cumming, William Frank Preston

    Fine scale studies are rarely performed to address landscape level responses to microclimatic variability. Is it the timing, distribution, and magnitude of soil temperature and moisture that affects what species emerge each season and, in turn, their resilience to fluctuations in microclimate. For this dissertation research, I evaluated the response of vegetation change to microclimatic variability within two communities over a three year period (2009-2012) utilizing 25 meter transects at two locations along the Front Range of Colorado near Boulder, CO and Golden, CO respectively. To assess microclimatic variability, spatial and temporal autocorrelation analyses were performed with soil temperature and moisture. Species cover was assessed along several line transects and correlated with microclimatic variability. Spatial and temporal autocorrelograms are useful tools in identifying the degree of dependency of soil temperature and moisture on the distance and time between pairs of measurements. With this analysis I found that a meter spatial resolution and two-hour measurements are sufficient to capture the fine scale variability in soil properties throughout the year. By comparing this to in situ measurements of soil properties and species percent cover I found that there are several plant functional types and/or species origin in particular that are more sensitive to variations in temperature and moisture than others. When all seasons, locations, correlations, and regional climate are looked at, it is the month of March that stands out in terms of significance. Additionally, of all of the vegetation types represented at these two sites C4, C3, native, non-native, and forb species seem to be the most sensitive to fluctuations in soil temperature, moisture, and regional climate in the spring season. The steady decline in percent species cover the study period and subsequent decrease in percent species cover and size at both locations may indicate that certain are

  4. Spatial Heterogeneity in Ecologically Important Climate Variables at Coarse and Fine Scales in a High-Snow Mountain Landscape

    PubMed Central

    Ford, Kevin R.; Ettinger, Ailene K.; Lundquist, Jessica D.; Raleigh, Mark S.; Hille Ris Lambers, Janneke

    2013-01-01

    Climate plays an important role in determining the geographic ranges of species. With rapid climate change expected in the coming decades, ecologists have predicted that species ranges will shift large distances in elevation and latitude. However, most range shift assessments are based on coarse-scale climate models that ignore fine-scale heterogeneity and could fail to capture important range shift dynamics. Moreover, if climate varies dramatically over short distances, some populations of certain species may only need to migrate tens of meters between microhabitats to track their climate as opposed to hundreds of meters upward or hundreds of kilometers poleward. To address these issues, we measured climate variables that are likely important determinants of plant species distributions and abundances (snow disappearance date and soil temperature) at coarse and fine scales at Mount Rainier National Park in Washington State, USA. Coarse-scale differences across the landscape such as large changes in elevation had expected effects on climatic variables, with later snow disappearance dates and lower temperatures at higher elevations. However, locations separated by small distances (∼20 m), but differing by vegetation structure or topographic position, often experienced differences in snow disappearance date and soil temperature as great as locations separated by large distances (>1 km). Tree canopy gaps and topographic depressions experienced later snow disappearance dates than corresponding locations under intact canopy and on ridges. Additionally, locations under vegetation and on topographic ridges experienced lower maximum and higher minimum soil temperatures. The large differences in climate we observed over small distances will likely lead to complex range shift dynamics and could buffer species from the negative effects of climate change. PMID:23762277

  5. Fine scale patterns in microbial extracellular enzyme activity during leaf litter decomposition in a stream and its floodplain.

    PubMed

    Smart, Kurt A; Jackson, Colin R

    2009-10-01

    Microorganisms mediate the decomposition of leaf-litter through the release of extracellular enzymes. The surfaces of decomposing leaves are both chemically and physically heterogeneous, and spatial patterns in microbial enzyme activity on the litter surface should provide insights into fine-scale patterns of leaf-litter decomposition. Platanus occidentalis leaves were collected from the floodplain of a third-order stream in northern Mississippi, enclosed in individual litter bags, and placed in the stream channel and in the floodplain. Replicate leaves were collected approximately monthly over a 9-month period and assayed for spatial variation in microbial extracellular enzyme activity and rates of organic matter (OM) decomposition. Spatial variation in enzyme activity was measured by sampling 96 small discs (5-mm diameter) cut from each leaf. Discs were assayed for the activity of enzymes involved in lignin (oxidative enzymes) and cellulose (beta-glucosidase, cellobiohydrolase) degradation. Rates of OM loss were greater in the stream than the floodplain. Activities of all enzymes displayed high variability in both environments, with severalfold differences across individual leaves, and replicate leaves varied greatly in their distribution of activities. Geostatistical analysis revealed no clear patterns in spatial distribution of activity over time or among replicates, and replicate leaves were highly variable. These results show that fine-scale spatial heterogeneity occurs on decomposing leaves, but the level of spatial variability varies among individual leaves at the measured spatial scales. This study is the first to use geostatistical analyses to analyze landscape patterns of microbial activity on decomposing leaf litter and in conjunction with studies of the microbial community composition and/or substrate characteristics, should provide key insights into the function of these processes.

  6. Hyper-temporal LiDAR for tracking fine-scale changes in vegetation structure, phenology, and physiology

    NASA Astrophysics Data System (ADS)

    Magney, T. S.; Vierling, L. A.; Eitel, J.; Greaves, H.

    2015-12-01

    Vegetation three-dimensional (3-D) structure is inherently dynamic - plants alter both the allocation of resources within the canopy and branch/shoot morphology at short time-steps to acclimate to local environmental conditions and maximize photosynthetic potential. However, 3-D structure is often ignored in ecological studies because it is difficult to characterize using traditional field methods. Terrestrial laser scanning (TLS) is a rapidly maturing technique to complement and enhance traditional field methods for quantifying 3-D geometric properties of ecosystems. Two major limitations of TLS include the low temporal resolution that often exists between each data acquisition, and the relatively high cost of such systems (entry level systems cost >$40,000 USD) that puts this method out of reach for many potential users. Consequently, TLS is currently limited as a mainstream method for capturing 3-D geometric ecosystem dynamics. Over the last several years, we have been developing a field-ready autonomously operating terrestrial laser scanner (ATLS) capable of monitoring fine-scale changes in vegetation structure on a daily time-step. We will present an overview of recent findings using the ATLS to track changes in vegetation structure in low-stature ecosystems - from cropping system dynamics to Arctic tundra phenology. Further, we will discuss the potential for laser intensity return information from both an ATLS and TLS to track changes in plant phenology and physiology (Chlorophyll content, photoprotective mechanisms, moisture) that occur simultaneously - or prior to - changes in vegetation structure. Our results suggest that fine-scale mapping of plant structure, phenology, and physiology using information from TLS and ATLS could provide new insights into vegetation dynamics in space and time.

  7. Fine-scale genetic structure and cryptic associations reveal evidence of kin-based sociality in the African forest elephant.

    PubMed

    Schuttler, Stephanie G; Philbrick, Jessica A; Jeffery, Kathryn J; Eggert, Lori S

    2014-01-01

    Spatial patterns of relatedness within animal populations are important in the evolution of mating and social systems, and have the potential to reveal information on species that are difficult to observe in the wild. This study examines the fine-scale genetic structure and connectivity of groups within African forest elephants, Loxodonta cyclotis, which are often difficult to observe due to forest habitat. We tested the hypothesis that genetic similarity will decline with increasing geographic distance, as we expect kin to be in closer proximity, using spatial autocorrelation analyses and Tau K(r) tests. Associations between individuals were investigated through a non-invasive genetic capture-recapture approach using network models, and were predicted to be more extensive than the small groups found in observational studies, similar to fission-fusion sociality found in African savanna (Loxodonta africana) and Asian (Elephas maximus) species. Dung samples were collected in Lopé National Park, Gabon in 2008 and 2010 and genotyped at 10 microsatellite loci, genetically sexed, and sequenced at the mitochondrial DNA control region. We conducted analyses on samples collected at three different temporal scales: a day, within six-day sampling sessions, and within each year. Spatial autocorrelation and Tau K(r) tests revealed genetic structure, but results were weak and inconsistent between sampling sessions. Positive spatial autocorrelation was found in distance classes of 0-5 km, and was strongest for the single day session. Despite weak genetic structure, individuals within groups were significantly more related to each other than to individuals between groups. Social networks revealed some components to have large, extensive groups of up to 22 individuals, and most groups were composed of individuals of the same matriline. Although fine-scale population genetic structure was weak, forest elephants are typically found in groups consisting of kin and based on matrilines

  8. Strong philopatry derived from capture-recapture records does not lead to fine-scale genetic differentiation in lesser kestrels.

    PubMed

    Alcaide, Miguel; Serrano, David; Tella, José L; Negro, Juan J

    2009-03-01

    1. The integration of capture-recapture and molecular approaches can improve our understanding of the consequences of habitat fragmentation on population connectivity. Here we employed microsatellites to test dispersal hypotheses derived from intense and long-term ringing programmes of the lesser kestrel Falco naumanni in Western Europe. 2. Re-encounters of 1308 marked individuals in Spain have revealed that most first-time breeders settled within 10 km from their natal colony, with a negative association between dispersal and geographical distance. Although these findings would predict fine-scale spatial patterns of genetic differentiation, the genetic impact of rarely reported events concerning long-distance effective dispersal (> 100 km) is unknown. 3. First, we investigated a spatially structured and geographically isolated population located in north-eastern Spain, where capture-recapture records and genetic data could be appropriately compared over similar spatial and temporal scales. Spatial autocorrelation analyses (N = 174 nestlings from different broods) did not reveal either significant differences in average relatedness at any distance class nor decreased relatedness as a function of distance. At a broader spatial scale, Bayesian analysis of population structure (N = 432 nestlings) indicated panmixia across Western Europe. However, F(ST) comparisons between four geographically distinct populations indicated low but significant genetic differentiation. 4. Our genetic data would therefore challenge traditional assumptions associating philopatry with the emergence of fine-scale genetic structuring. This could be because even low levels of gene flow are enough to preclude the development of local genetic structure. Nevertheless, the analysis of a geographically isolated and small population from Southern France exemplifies a situation in which restricted dispersal has translated into weak but consistently significant genetic differentiation. 5. Relevant to

  9. Effects of seed bank disturbance on the fine-scale genetic structure of populations of the rare shrub Grevillea macleayana.

    PubMed

    England, P R; Whelan, R J; Ayre, D J

    2003-11-01

    Dispersal in most plants is mediated by the movement of seeds and pollen, which move genes across the landscape differently. Grevillea macleayana is a rare, fire-dependent Australian shrub with large seeds lacking adaptations for dispersal; yet it produces inflorescences adapted to pollination by highly mobile vertebrates (eg birds). Interpreting fine-scale genetic structure in the light of these two processes is confounded by the recent imposition of anthropogenic disturbances with potentially contrasting genetic consequences: (1) the unusual foraging behaviour of exotic honeybees and 2. widespread disturbance of the soil-stored seedbank by road building and quarrying. To test for evidence of fine-scale genetic structure within G. macleayana populations and to test the prediction that such structure might be masked by disturbance of the seed bank, we sampled two sites in undisturbed habitat and compared their genetic structure with two sites that had been strongly affected by road building using a test for spatial autocorrelation of genotypes. High selfing levels inferred from genotypes at all four sites implies that pollen dispersal is limited. Consistent with this, we observed substantial spatial clustering of genes at 10 m or less in the two undisturbed populations and argue that this reflects the predicted effects of both high selfing levels and limited seed dispersal. In contrast, at the two sites disturbed by road building, spatial autocorrelation was weak. This suggests there has been mixing of the seed bank, counteracting the naturally low dispersal and elevated selfing due to honeybees. Pollination between near neighbours with reduced relatedness potentially has fitness consequences for G. macleayana in disturbed sites.

  10. Fine-scale population structure and riverscape genetics of brook trout (Salvelinus fontinalis) distributed continuously along headwater channel networks

    USGS Publications Warehouse

    Kanno, Yoichiro; Vokoun, Jason C.; Letcher, Benjamin H.

    2011-01-01

    Linear and heterogeneous habitat makes headwater stream networks an ideal ecosystem in which to test the influence of environmental factors on spatial genetic patterns of obligatory aquatic species. We investigated fine-scale population structure and influence of stream habitat on individual-level genetic differentiation in brook trout (Salvelinus fontinalis) by genotyping eight microsatellite loci in 740 individuals in two headwater channel networks (7.7 and 4.4 km) in Connecticut, USA. A weak but statistically significant isolation-by-distance pattern was common in both sites. In the field, many tagged individuals were recaptured in the same 50-m reaches within a single field season (summer to fall). One study site was characterized with a hierarchical population structure, where seasonal barriers (natural falls of 1.5–2.5 m in height during summer base-flow condition) greatly reduced gene flow and perceptible spatial patterns emerged because of the presence of tributaries, each with a group of genetically distinguishable individuals. Genetic differentiation increased when pairs of individuals were separated by high stream gradient (steep channel slope) or warm stream temperature in this site, although the evidence of their influence was equivocal. In a second site, evidence for genetic clusters was weak at best, but genetic differentiation between individuals was positively correlated with number of tributary confluences. We concluded that the population-level movement of brook trout was limited in the study headwater stream networks, resulting in the fine-scale population structure (genetic clusters and clines) even at distances of a few kilometres, and gene flow was mitigated by ‘riverscape’ variables, particularly by physical barriers, waterway distance (i.e. isolation-by-distance) and the presence of tributaries.

  11. Fine-Scale Genetic Structure and Cryptic Associations Reveal Evidence of Kin-Based Sociality in the African Forest Elephant

    PubMed Central

    Schuttler, Stephanie G.; Philbrick, Jessica A.; Jeffery, Kathryn J.; Eggert, Lori S.

    2014-01-01

    Spatial patterns of relatedness within animal populations are important in the evolution of mating and social systems, and have the potential to reveal information on species that are difficult to observe in the wild. This study examines the fine-scale genetic structure and connectivity of groups within African forest elephants, Loxodonta cyclotis, which are often difficult to observe due to forest habitat. We tested the hypothesis that genetic similarity will decline with increasing geographic distance, as we expect kin to be in closer proximity, using spatial autocorrelation analyses and Tau Kr tests. Associations between individuals were investigated through a non-invasive genetic capture-recapture approach using network models, and were predicted to be more extensive than the small groups found in observational studies, similar to fission-fusion sociality found in African savanna (Loxodonta africana) and Asian (Elephas maximus) species. Dung samples were collected in Lopé National Park, Gabon in 2008 and 2010 and genotyped at 10 microsatellite loci, genetically sexed, and sequenced at the mitochondrial DNA control region. We conducted analyses on samples collected at three different temporal scales: a day, within six-day sampling sessions, and within each year. Spatial autocorrelation and Tau Kr tests revealed genetic structure, but results were weak and inconsistent between sampling sessions. Positive spatial autocorrelation was found in distance classes of 0–5 km, and was strongest for the single day session. Despite weak genetic structure, individuals within groups were significantly more related to each other than to individuals between groups. Social networks revealed some components to have large, extensive groups of up to 22 individuals, and most groups were composed of individuals of the same matriline. Although fine-scale population genetic structure was weak, forest elephants are typically found in groups consisting of kin and based on matrilines

  12. Fine-Scale Exposure to Allergenic Pollen in the Urban Environment: Evaluation of Land Use Regression Approach

    PubMed Central

    Hjort, Jan; Hugg, Timo T.; Antikainen, Harri; Rusanen, Jarmo; Sofiev, Mikhail; Kukkonen, Jaakko; Jaakkola, Maritta S.; Jaakkola, Jouni J.K.

    2015-01-01

    Background: Despite the recent developments in physically and chemically based analysis of atmospheric particles, no models exist for resolving the spatial variability of pollen concentration at urban scale. Objectives: We developed a land use regression (LUR) approach for predicting spatial fine-scale allergenic pollen concentrations in the Helsinki metropolitan area, Finland, and evaluated the performance of the models against available empirical data. Methods: We used grass pollen data monitored at 16 sites in an urban area during the peak pollen season and geospatial environmental data. The main statistical method was generalized linear model (GLM). Results: GLM-based LURs explained 79% of the spatial variation in the grass pollen data based on all samples, and 47% of the variation when samples from two sites with very high concentrations were excluded. In model evaluation, prediction errors ranged from 6% to 26% of the observed range of grass pollen concentrations. Our findings support the use of geospatial data–based statistical models to predict the spatial variation of allergenic grass pollen concentrations at intra-urban scales. A remote sensing–based vegetation index was the strongest predictor of pollen concentrations for exposure assessments at local scales. Conclusions: The LUR approach provides new opportunities to estimate the relations between environmental determinants and allergenic pollen concentration in human-modified environments at fine spatial scales. This approach could potentially be applied to estimate retrospectively pollen concentrations to be used for long-term exposure assessments. Citation: Hjort J, Hugg TT, Antikainen H, Rusanen J, Sofiev M, Kukkonen J, Jaakkola MS, Jaakkola JJ. 2016. Fine-scale exposure to allergenic pollen in the urban environment: evaluation of land use regression approach. Environ Health Perspect 124:619–626; http://dx.doi.org/10.1289/ehp.1509761 PMID:26452296

  13. Effects of currents and tides on fine-scale use of marine bird habitats in a Southeast Alaska hotspot

    USGS Publications Warehouse

    Drew, Gary S.; Piatt, John F.; Hill, David J.

    2013-01-01

    Areas with high species richness have become focal points in the establishment of marine protected areas, but an understanding of the factors that support this diversity is still incomplete. In coastal areas, tidal currents—modulated by bathymetry and manifested in variable speeds—are a dominant physical feature of the environment. However, difficulties resolving tidally affected currents and depths at fine spatial-temporal scales have limited our ability to understand their influence the distribution of marine birds. We used a hydrographic model of the water mass in Glacier Bay, Alaska to link depths and current velocities with the locations of 15 common marine bird species observed during fine-scale boat-based surveys of the bay conducted during June of four consecutive years (2000-2003). Marine birds that forage on the bottom tended to occupy shallow habitats with slow-moving currents; mid-water foragers used habitats with intermediate depths and current speeds; and surface-foraging species tended to use habitats with fast-moving, deep waters. Within foraging groups there was variability among species in their use of habitats. While species obligated to foraging near bottom were constrained to use similar types of habitat, species in the mid-water foraging group were associated with a wider range of marine habitat characteristics. Species also showed varying levels of site use depending on tide stage. The dramatic variability in bottom topography—especially the presence of numerous sills, islands, headlands and channels—and large tidal ranges in Glacier Bay create a wide range of current-affected fine-scale foraging habitats that may contribute to the high diversity of marine bird species found there.

  14. How Elephant Seals (Mirounga leonina) Adjust Their Fine Scale Horizontal Movement and Diving Behaviour in Relation to Prey Encounter Rate

    PubMed Central

    Jouma’a, Joffrey; Picard, Baptiste; Guinet, Christophe

    2016-01-01

    Understanding the diving behaviour of diving predators in relation to concomitant prey distribution could have major practical applications in conservation biology by allowing the assessment of how changes in fine scale prey distribution impact foraging efficiency and ultimately population dynamics. The southern elephant seal (Mirounga leonina, hereafter SES), the largest phocid, is a major predator of the southern ocean feeding on myctophids and cephalopods. Because of its large size it can carry bio-loggers with minimal disturbance. Moreover, it has great diving abilities and a wide foraging habitat. Thus, the SES is a well suited model species to study predator diving behaviour and the distribution of ecologically important prey species in the Southern Ocean. In this study, we examined how SESs adjust their diving behaviour and horizontal movements in response to fine scale prey encounter densities using high resolution accelerometers, magnetometers, pressure sensors and GPS loggers. When high prey encounter rates were encountered, animals responded by (1) diving and returning to the surface with steeper angles, reducing the duration of transit dive phases (thus improving dive efficiency), and (2) exhibiting more horizontally and vertically sinuous bottom phases. In these cases, the distance travelled horizontally at the surface was reduced. This behaviour is likely to counteract horizontal displacement from water currents, as they try to remain within favourable prey patches. The prey encounter rate at the bottom of dives decreased with increasing diving depth, suggesting a combined effect of decreased accessibility and prey density with increasing depth. Prey encounter rate also decreased when the bottom phases of dives were spread across larger vertical extents of the water column. This result suggests that the vertical aggregation of prey can regulate prey density, and as a consequence impact the foraging success of SESs. To our knowledge, this is one of

  15. Fine-scale natal homing and localized movement as shaped by sex and spawning habitat in chinook salmon

    USGS Publications Warehouse

    Neville, Helen; Isaak, Daniel; Dunham, J.B.; Thurow, Russel; Rieman, B.

    2006-01-01

    Natal homing is a hallmark of the life history of salmonid fishes, but the spatial scale of homing within local, naturally reproducing salmon populations is still poorly understood. Accurate homing (paired with restricted movement) should lead to the existence of fine-scale genetic structuring due to the spatial clustering of related individuals on spawning grounds. Thus, we explored the spatial resolution of natal homing using genetic associations among individual Chinook salmon (Oncorhynchus tshawytscha) in an interconnected stream network. We also investigated the relationship between genetic patterns and two factors hypothesized to influence natal homing and localized movements at finer scales in this species, localized patterns in the distribution of spawning gravels and sex. Spatial autocorrelation analyses showed that spawning locations in both sub-basins of our study site were spatially clumped, but the upper sub-basin generally had a larger spatial extent and continuity of redd locations than the lower sub-basin, where the distribution of redds and associated habitat conditions were more patchy. Male genotypes were not autocorrelated at any spatial scale in either sub-basin. Female genotypes showed significant spatial autocorrelation and genetic patterns for females varied in the direction predicted between the two sub-basins, with much stronger autocorrelation in the sub-basin with less continuity in spawning gravels. The patterns observed here support predictions about differential constraints and breeding tactics between the two sexes and the potential for fine-scale habitat structure to influence the precision of natal homing and localized movements of individual Chinook salmon on their breeding grounds.

  16. Fronts and Fine-Scale Distribution of Three Cetacean Species within the Dynamic Mid-Atlantic Bight Shelf Break System

    NASA Astrophysics Data System (ADS)

    LaBrecque, E.; Lawson, G. L.; Halpin, P. N.

    2016-02-01

    The Mid-Atlantic Bight (MAB) shelf break region is a highly dynamic and productive area that provides a wide range of habitat to many marine species over every trophic level. At least 23 cetacean species occur in the MAB shelf break region and their distributions are thought to be influenced by the MAB shelf break front. This research characterizes the spatial distribution of common dolphins (Delphinus delphis), Risso's dolphins (Grampus griseus), and sperm whales (Physeter macrocephalus) through multi-dimensional scaling (MDS), classification tree analysis and random forest analysis of marine mammal line-transect survey data, multi-frequency active acoustic data and fine-scale in situ hydrographic data. Multi-frequency active acoustic data were broadly classified into proxies of middle trophic level groups through frequency response methods. Surface temperature fronts were observed in all sections of the shelf break region. The strongest surface fronts were within 15 km of the shelf break ( 150 meter isobath) on 10 of the 19 cross shelf transects. MDS presented clear environmental distinction between common dolphins and Risso's dolphins and sperm whales. Environmental separation between Risso's dolphins and sperm whales was evident but less distinct. In both the classification tree and random forest analyzes, the common dolphin models had the least error (0.33 and 0.28 respectively). Depths less than 145 meters and area within 10 km shelf-side of the shelf break were the primary variables that described common dolphin habitat. Risso's dolphin habitat was selected as the area between 20 km shelf-side to 20 km offshore of the strongest surface thermal gradient. Offshore salinity and distances greater than 26 km to density fronts were the primary variables selected to describe sperm whale habitat. When mapped back into geographic space, these three cetacean species occupy different fine-scale habitats within the dynamic Mid-Atlantic Bight shelf break system.

  17. Spatial heterogeneity in ecologically important climate variables at coarse and fine scales in a high-snow mountain landscape.

    PubMed

    Ford, Kevin R; Ettinger, Ailene K; Lundquist, Jessica D; Raleigh, Mark S; Hille Ris Lambers, Janneke

    2013-01-01

    Climate plays an important role in determining the geographic ranges of species. With rapid climate change expected in the coming decades, ecologists have predicted that species ranges will shift large distances in elevation and latitude. However, most range shift assessments are based on coarse-scale climate models that ignore fine-scale heterogeneity and could fail to capture important range shift dynamics. Moreover, if climate varies dramatically over short distances, some populations of certain species may only need to migrate tens of meters between microhabitats to track their climate as opposed to hundreds of meters upward or hundreds of kilometers poleward. To address these issues, we measured climate variables that are likely important determinants of plant species distributions and abundances (snow disappearance date and soil temperature) at coarse and fine scales at Mount Rainier National Park in Washington State, USA. Coarse-scale differences across the landscape such as large changes in elevation had expected effects on climatic variables, with later snow disappearance dates and lower temperatures at higher elevations. However, locations separated by small distances (∼20 m), but differing by vegetation structure or topographic position, often experienced differences in snow disappearance date and soil temperature as great as locations separated by large distances (>1 km). Tree canopy gaps and topographic depressions experienced later snow disappearance dates than corresponding locations under intact canopy and on ridges. Additionally, locations under vegetation and on topographic ridges experienced lower maximum and higher minimum soil temperatures. The large differences in climate we observed over small distances will likely lead to complex range shift dynamics and could buffer species from the negative effects of climate change.

  18. How Elephant Seals (Mirounga leonina) Adjust Their Fine Scale Horizontal Movement and Diving Behaviour in Relation to Prey Encounter Rate.

    PubMed

    Le Bras, Yves; Jouma'a, Joffrey; Picard, Baptiste; Guinet, Christophe

    2016-01-01

    Understanding the diving behaviour of diving predators in relation to concomitant prey distribution could have major practical applications in conservation biology by allowing the assessment of how changes in fine scale prey distribution impact foraging efficiency and ultimately population dynamics. The southern elephant seal (Mirounga leonina, hereafter SES), the largest phocid, is a major predator of the southern ocean feeding on myctophids and cephalopods. Because of its large size it can carry bio-loggers with minimal disturbance. Moreover, it has great diving abilities and a wide foraging habitat. Thus, the SES is a well suited model species to study predator diving behaviour and the distribution of ecologically important prey species in the Southern Ocean. In this study, we examined how SESs adjust their diving behaviour and horizontal movements in response to fine scale prey encounter densities using high resolution accelerometers, magnetometers, pressure sensors and GPS loggers. When high prey encounter rates were encountered, animals responded by (1) diving and returning to the surface with steeper angles, reducing the duration of transit dive phases (thus improving dive efficiency), and (2) exhibiting more horizontally and vertically sinuous bottom phases. In these cases, the distance travelled horizontally at the surface was reduced. This behaviour is likely to counteract horizontal displacement from water currents, as they try to remain within favourable prey patches. The prey encounter rate at the bottom of dives decreased with increasing diving depth, suggesting a combined effect of decreased accessibility and prey density with increasing depth. Prey encounter rate also decreased when the bottom phases of dives were spread across larger vertical extents of the water column. This result suggests that the vertical aggregation of prey can regulate prey density, and as a consequence impact the foraging success of SESs. To our knowledge, this is one of

  19. Observability of fine-scale ocean dynamics in the northwestern Mediterranean Sea

    NASA Astrophysics Data System (ADS)

    Morrow, Rosemary; Carret, Alice; Birol, Florence; Nino, Fernando; Valladeau, Guillaume; Boy, Francois; Bachelier, Celine; Zakardjian, Bruno

    2017-01-01

    band.

  20. Cortico-pallidal oscillatory connectivity in patients with dystonia.

    PubMed

    Neumann, Wolf-Julian; Jha, Ashwani; Bock, Antje; Huebl, Julius; Horn, Andreas; Schneider, Gerd-Helge; Sander, Tillmann H; Litvak, Vladimir; Kühn, Andrea A

    2015-07-01

    Primary dystonia has been associated with an underlying dysfunction of a wide network of brain regions including the motor cortex, basal ganglia, cerebellum, brainstem and spinal cord. Dystonia can be effectively treated by pallidal deep brain stimulation although the mechanism of this effect is not well understood. Here, we sought to characterize cortico-basal ganglia functional connectivity using a frequency-specific measure of connectivity-coherence. We recorded direct local field potentials from the human pallidum simultaneously with whole head magnetoencephalography to characterize functional connectivity in the cortico-pallidal oscillatory network in nine patients with idiopathic dystonia. Three-dimensional cortico-pallidal coherence images were compared to surrogate images of phase shuffled data across patients to reveal clusters of significant coherence (family-wise error P < 0.01, voxel extent 1000). Three frequency-specific, spatially-distinct cortico-pallidal networks have been identified: a pallido-temporal source of theta band (4-8 Hz) coherence, a pallido-cerebellar source of alpha band (7-13 Hz) coherence and a cortico-pallidal source of beta band (13-30 Hz) coherence over sensorimotor areas. Granger-based directionality analysis revealed directional coupling with the pallidal local field potentials leading in the theta and alpha band and the magnetoencephalographic cortical source leading in the beta band. The degree of pallido-cerebellar coupling showed an inverse correlation with dystonic symptom severity. Our data extend previous findings in patients with Parkinson's disease describing motor cortex-basal ganglia oscillatory connectivity in the beta band to patients with dystonia. Source coherence analysis revealed two additional frequency-specific networks involving the temporal cortex and the cerebellum. Pallido-cerebellar oscillatory connectivity and its association with dystonic symptoms provides further confirmation of cerebellar involvement

  1. Microscale mapping of oscillatory flows

    NASA Astrophysics Data System (ADS)

    Nedev, Spas; Carretero-Palacios, S.; Kirchner, S. R.; Jäckel, F.; Feldmann, J.

    2014-10-01

    We present an optofluidic method that allows the two-dimensional vectorial near-field mapping of oscillatory flows with micron-scale resolution. An oscillatory flow created by a microsource (an optically trapped silica particle set to oscillate in a dipole-type mode) is detected by another twin silica particle independently trapped and located in the vicinity of the source. Fourier analysis of the motion of the detecting particle at different points in space and time renders the vectorial velocity map around the oscillating microsphere. The method introduced here paves the way for in-situ characterization of fast mixing microscale devices and for new detection methods able to provide location and recognition (due to the field pattern) of moving sources that may be applied to both artificial and living microobjects, including macromolecules, cells, and microorganisms.

  2. Oscillatory control of insulin secretion.

    PubMed

    Tengholm, Anders; Gylfe, Erik

    2009-01-15

    Pancreatic beta-cells possess an inherent ability to generate oscillatory signals that trigger insulin release. Coordination of the secretory activity among beta-cells results in pulsatile insulin secretion from the pancreas, which is considered important for the action of the hormone in the target tissues. This review focuses on the mechanisms underlying oscillatory control of insulin secretion at the level of the individual beta-cell. Recent studies have demonstrated that oscillations of the cytoplasmic Ca(2+) concentration are synchronized with oscillations in beta-cell metabolism, intracellular cAMP concentration, phospholipase C activity and plasma membrane phosphoinositide lipid concentrations. There are complex interdependencies between the different messengers and signalling pathways that contribute to amplitude regulation and shaping of the insulin secretory response to nutrient stimuli and neurohormonal modulators. Several of these pathways may be important pharmacological targets for improving pulsatile insulin secretion in type 2 diabetes.

  3. Oscillatory phase shapes syllable perception

    PubMed Central

    ten Oever, Sanne; Sack, Alexander T.

    2015-01-01

    The role of oscillatory phase for perceptual and cognitive processes is being increasingly acknowledged. To date, little is known about the direct role of phase in categorical perception. Here we show in two separate experiments that the identification of ambiguous syllables that can either be perceived as /da/ or /ga/ is biased by the underlying oscillatory phase as measured with EEG and sensory entrainment to rhythmic stimuli. The measured phase difference in which perception is biased toward /da/ or /ga/ exactly matched the different temporal onset delays in natural audiovisual speech between mouth movements and speech sounds, which last 80 ms longer for /ga/ than for /da/. These results indicate the functional relationship between prestimulus phase and syllable identification, and signify that the origin of this phase relationship could lie in exposure and subsequent learning of unique audiovisual temporal onset differences. PMID:26668393

  4. Regulation of yeast oscillatory dynamics

    PubMed Central

    Murray, Douglas B.; Beckmann, Manfred; Kitano, Hiroaki

    2007-01-01

    When yeast cells are grown continuously at high cell density, a respiratory oscillation percolates throughout the population. Many essential cellular functions have been shown to be separated temporally during each cycle; however, the regulatory mechanisms involved in oscillatory dynamics remain to be elucidated. Through GC-MS analysis we found that the majority of metabolites show oscillatory dynamics, with 70% of the identified metabolite concentrations peaking in conjunction with NAD(P)H. Through statistical analyses of microarray data, we identified that biosynthetic events have a defined order, and this program is initiated when respiration rates are increasing. We then combined metabolic, transcriptional data and statistical analyses of transcription factor activity, identified the top oscillatory parameters, and filtered a large-scale yeast interaction network according to these parameters. The analyses and controlled experimental perturbation provided evidence that a transcriptional complex formed part of the timing circuit for biosynthetic, reductive, and cell cycle programs in the cell. This circuitry does not act in isolation because both have strong translational, proteomic, and metabolic regulatory mechanisms. Our data lead us to conclude that the regulation of the respiratory oscillation revolves around coupled subgraphs containing large numbers of proteins and metabolites, with a potential to oscillate, and no definable hierarchy, i.e., heterarchical control. PMID:17284613

  5. Multiphase patterns in periodically forced oscillatory systems

    SciTech Connect

    Elphick, C.; Hagberg, A.; Meron, E.

    1999-05-01

    Periodic forcing of an oscillatory system produces frequency locking bands within which the system frequency is rationally related to the forcing frequency. We study extended oscillatory systems that respond to uniform periodic forcing at one quarter of the forcing frequency (the 4:1 resonance). These systems possess four coexisting stable states, corresponding to uniform oscillations with successive phase shifts of {pi}/2. Using an amplitude equation approach near a Hopf bifurcation to uniform oscillations, we study front solutions connecting different phase states. These solutions divide into two groups: {pi} fronts separating states with a phase shift of {pi} and {pi}/2 fronts separating states with a phase shift of {pi}/2. We find a type of front instability where a stationary {pi} front {open_quotes}decomposes{close_quotes} into a pair of traveling {pi}/2 fronts as the forcing strength is decreased. The instability is degenerate for an amplitude equation with cubic nonlinearities. At the instability point a continuous family of pair solutions exists, consisting of {pi}/2 fronts separated by distances ranging from zero to infinity. Quintic nonlinearities lift the degeneracy at the instability point but do not change the basic nature of the instability. We conjecture the existence of similar instabilities in higher 2n:1 resonances (n=3,4,{hor_ellipsis}) where stationary {pi} fronts decompose into {ital n} traveling {pi}/n fronts. The instabilities designate transitions from stationary two-phase patterns to traveling 2n-phase patterns. As an example, we demonstrate with a numerical solution the collapse of a four-phase spiral wave into a stationary two-phase pattern as the forcing strength within the 4:1 resonance is increased. {copyright} {ital 1999} {ital The American Physical Society}

  6. Computer-assisted experiments with oscillatory circuits

    NASA Astrophysics Data System (ADS)

    Fernandes, J. C.; Ferraz, A.; Rogalski, M. S.

    2010-03-01

    A basic setup for data acquisition and analysis from an oscillatory circuit is described, with focus on its application as either low-pass, high-pass, band-pass or band-reject frequency filter. A homemade board containing the RLC elements allows for the interchange of some of them, in particular, for the easy change of the R value, and this makes apparent for the student its influence on the damping factor. The function generator operates in the swap frequency mode over a suitable frequency range and all the circuit parameters are chosen to provide a reasonable set of data for all the electronic filters studied. The output data are acquired through a commercially available DAQ board and data analysis is performed using a graphing and fitting workspace. The main objective is to develop a methodology of teaching the laboratory material through a computer-based environment devised to help students to appreciate how the governing equations work and to visualize their practical applications.

  7. Fine-scale photochemical modeling of ozone and ammonium nitrate over California during CalNex 2010

    NASA Astrophysics Data System (ADS)

    Kelly, J.; Baker, K.; Misenis, C.; Gilman, J.; De Gouw, J. A.; Lerner, B. M.; Neuman, J. A.; Nowak, J. B.; Pollack, I. B.; Roberts, J. M.; Ryerson, T. B.; Warneke, C.; Williams, E. J.; Veres, P. R.; Murphy, J. G.; Markovic, M. Z.; VandenBoer, T. C.; Weber, R.

    2013-12-01

    Multiple areas of California are designated as nonattainment of the ozone and PM2.5 National Ambient Air Quality Standards making air quality (AQ) modeling for California an important aspect of national-scale modeling for EPA rulemaking. Fine-scale AQ modeling for key population centers in California is also useful to inform health and exposure studies. However, AQ modeling is challenging in California due to complex emissions, terrain, meteorology, and chemistry, and understanding model performance is difficult using routine network observations alone. In May-June 2010, the CalNex field study was conducted in California to answer important scientific questions related to air quality and climate processes. The field study provides a rich observational dataset for probing the performance of fine-scale AQ simulations and identifying causes of model performance limitations. In this study, we conduct fine-scale (4-km horizontal resolution) photochemical model simulations for California during May-June 2010 using the Community Multiscale Air Quality model with the Carbon Bond 05 and SAPRC07 gas-phase chemical mechanisms. Model predictions are then evaluated using observations from the CalNex ground, aircraft, and ship platforms in addition routine network observations. Our model evaluations focus on understanding predictions of ammonium nitrate and ozone concentrations given the importance of these pollutants to California's air quality. Model predictions of ammonium and nitrate have a slight low bias but are strongly correlated with network observations in Riverside and Bakersfield. The model tends to under-predict NH3 concentrations observed on the NOAA P3 aircraft near large NH3 sources in the San Joaquin Valley (SJV) and South Coast Air Basin (SoCAB). At the SJV ground site, NH3 predictions are of similar magnitude as observations, while NH3 tends to be over-predicted at the Pasadena ground site. Nitric acid is over-predicted during the day at the SJV ground site

  8. Oscillations during observations: Dynamic oscillatory networks serving visuospatial attention.

    PubMed

    Wiesman, Alex I; Heinrichs-Graham, Elizabeth; Proskovec, Amy L; McDermott, Timothy J; Wilson, Tony W

    2017-10-01

    The dynamic allocation of neural resources to discrete features within a visual scene enables us to react quickly and accurately to salient environmental circumstances. A network of bilateral cortical regions is known to subserve such visuospatial attention functions; however the oscillatory and functional connectivity dynamics of information coding within this network are not fully understood. Particularly, the coding of information within prototypical attention-network hubs and the subsecond functional connections formed between these hubs have not been adequately characterized. Herein, we use the precise temporal resolution of magnetoencephalography (MEG) to define spectrally specific functional nodes and connections that underlie the deployment of attention in visual space. Twenty-three healthy young adults completed a visuospatial discrimination task designed to elicit multispectral activity in visual cortex during MEG, and the resulting data were preprocessed and reconstructed in the time-frequency domain. Oscillatory responses were projected to the cortical surface using a beamformer, and time series were extracted from peak voxels to examine their temporal evolution. Dynamic functional connectivity was then computed between nodes within each frequency band of interest. We find that visual attention network nodes are defined functionally by oscillatory frequency, that the allocation of attention to the visual space dynamically modulates functional connectivity between these regions on a millisecond timescale, and that these modulations significantly correlate with performance on a spatial discrimination task. We conclude that functional hubs underlying visuospatial attention are segregated not only anatomically but also by oscillatory frequency, and importantly that these oscillatory signatures promote dynamic communication between these hubs. Hum Brain Mapp 38:5128-5140, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  9. Effect of fine scale microstructure and inclusions on the toughness of ultra high strength low alloy medium carbon steels

    NASA Astrophysics Data System (ADS)

    Choudhary, Pranay

    When fracture is due to micro-void coalescence the toughness of ultra high strength steels is determined by the nature of the inclusions in the steel and by the fine-scale microstructure of the steel. It has been previously shown for the steels HY180 (0.1 wt.% carbon) and AF1410 (0.16 wt.% carbon) that one can improve toughness by increasing inclusion spacing through the use of rare-earths and similarly increase toughness by having inclusion types that are resistant to void nucleation though the use of titanium additions. The purpose of this work has been to determine the extent to which rare-earth additions and titanium additions can be used to control inclusion characteristics and improve the toughness of ultra high strength low alloy steels such as 4340 (0.4 wt.% carbon) and 300M. Because silicon additions on the order of 2 wt.% can be used to increase the strength of 0.4 wt.% carbon low-alloy steels without resorting to increased carbon levels, this work also examined the degree to which silicon content influences the inclusion distributions when rare-earth additions or titanium additions are used to modify inclusion type. Two separate low-alloy systems, 4340 and Base+Ni+Si series alloys were investigated. Extensive mechanical testing was performed by tensile testing, plane strain fracture toughness tests and Charpy impact toughness tests. True stress-true strain curves were obtained by applying the method of Bridgman. The inclusion analysis of the micrographs obtained using SEM was used to obtain the average inclusion radius, inclusion volume fraction and inclusion spacing. Void nucleation curves were obtained to characterize the strain at which inclusions first nucleate voids. Subsequently the critical interfacial stress at which these inclusions nucleate voids was also obtained. The retained austenite content was measured using X-Ray diffraction while analysis of thin foils and extraction replicas was performed using Transmission Electron Microscopy (TEM

  10. Interaction between fine-scale landforms and vegetation patterns in alkali landscapes - case study based on remotely sensed data

    NASA Astrophysics Data System (ADS)

    Deák, Balázs; Valkó, Orsolya; Tóthmérész, Béla; Alexander, Cici; Mücke, Werner; Kania, Adam; Tamás, János; Heilmeier, Hermann

    2015-04-01

    Vertical position is an important driver of vegetation zonation at multiple scales, via determining abiotic environmental parameters like climate, soil properties and water balance. Despite small-scale elevation differences are proven to significantly influence soil salt content and water balance; relationships between elevation and vegetation types are rarely studied in inland alkali landscapes. Alkali landscapes of the Pannonian biogeographical region comprise the most connected salt-affected landscape in continental Europe which provides unique opportunities for studying elevation-vegetation relationships. For linking elevation data with vegetation patterns, remote sensing techniques offer a vital solution. Application of airborne laser scanning is a feasible tool for providing an elevation model of extent areas. Our goal was to test the correlation between fine-scale differences in vertical position and vegetation patterns in inland alkali landscapes by using field vegetation data and elevation data generated using airborne laser scanning. We studied whether the vertical position influences vegetation patterns at the level of main vegetation categories or even at the level of associations. Our study sites were situated in a lowland alkali landscape in Hortobágy National Park (East-Hungary). Associations of the study site can be grouped into four main vegetation categories: (i) loess grasslands, (ii) alkali steppes, (iii) open alkali swards and (iv) alkali meadows. Even though we detected a very limited range in the vertical position (121 cm) of the main vegetation categories; they were well separated along their vertical positions. The detected elevation gradient likely corresponds to environmental gradients (soil type, salt accumulation and water balance). At the level of association types, a more detailed elevation-based distinction was also possible in many cases. Based on the digital terrain model, we revealed a fine-scale vertical vegetation gradient. Our

  11. The fine-scale remobilization of metals in the surface sediment of the North-East Atlantic

    NASA Astrophysics Data System (ADS)

    Fones, Gary R.; Davison, William; Hamilton-Taylor, John

    2004-08-01

    Vertical profiles of trace metals were measured at 1-mm intervals by deploying DGT probes in sediment cores collected from the deep Atlantic Ocean (Feni Drift) before and after the spring phytoplankton bloom. DGT (diffusive gradients in thin-films) accumulates metals on a chelating resin after their diffusive transport through a layer of hydrogel. The mean concentration of metal in the porewaters at the surface of the device during its deployment was derived from the measured mass of metal. Well-defined laboratory systems were used to establish the reproducibility and accuracy of the DGT technique for measuring metals at 1-mm intervals. The Fe and Mn profiles showed the expected redox sequence with depth, with additional fine-scale (2-5 mm) features. The close correspondence between the Mn and Co profiles, on both coarse and fine scales, showed that their chemistry is closely coupled in sediments as well as water columns. Changes in the background concentrations of Cd, Cu, Ni and Zn with depth were well correlated with Mn and Co, but the four metals also displayed mm-scale maxima that were largely independent of Mn, Co or Fe. Two-dimensional measurements at a 100- μm resolution on a DGT probe, deployed in situ with an autonomous lander, showed that the maxima were most likely associated with near-spherical, highly localised sources. The results were consistent with release of Cd, Cu, Ni and Zn from organic and planktonic skeletal material. Where there was associated release of Mn and/or Fe, through their oxides acting as electron acceptors in the decomposition of the organic matter, trace metals could also be supplied by release from the oxides. The microniches responsible for high local concentrations of metals in the porewaters were hypothesised to be due to downward mixing of material by burrowing organisms, known to be prevalent in these sediments. Much of this material appeared to be present as faecal pellets of various origins, with sizes in the range of 50

  12. Fine-scale spatial structure of the exploited infaunal bivalve Cerastoderma edule on the French Atlantic coast

    NASA Astrophysics Data System (ADS)

    Boldina, Inna; Beninger, Peter G.

    2013-02-01

    Investigations of biomass, production, and anthropogenic impact require knowledge of the spatial distribution of the species concerned. Studies of the spatial distribution of soft-sediment infauna are inherently difficult, because the organisms are generally not readily visible, necessitating painstaking excavation. Although the large-scale (tens of km) distribution patterns of infaunal bivalves have been studied previously, the fine-scale (1 to tens of meters) has received much less attention. We investigated the fine-scale spatial distribution of the edible cockle Cerastoderma edule at a fishing-impacted site and a non-impacted site on an intertidal mudflat in Bourgneuf Bay, France, in 2009-2010. A preliminary study using a 1 m spatial lag was performed to determine the optimum lags for a nested sampling design. Cohorts were identified using Bhattacharya-resolved size-frequency distributions and verification of isotropy, and the spatial characteristics of each cohort were determined using Moran's I auto-correlation coefficient. The non-impacted site presented one strongly-aggregated main cohort, C3, (Moran's I = 0.67 to - 0.34, spatial range 16 to 20 m, inter-patch distance 41 to 51 m). The impacted site presented two main cohorts, C2 (1.31 cm mean shell length, SL) and C3 (2.11 cm SL) both of which also showed a patchy spatial distribution (C2: Moran's I = 0.7 to - 0.72, spatial range 22 to 35 m; inter-patch distance 63 to 90 m; C3: Moran's I = 0.41 to - 0.63, spatial range 36 to 58 m, inter-patch distance not defined). The C3 cohort was less aggregated than the C2; possibly due to the homogenizing effect of fishing, which typically proceeds via a Lévy walk foraging model. Our results show that the spatial distributions of C. edule retained a strongly aggregated character over the 8 months of the study, suggesting that these characteristics are powerfully maintained by recruitment/post-recruitment processes, despite intense fishing pressure throughout the

  13. Caribou, water, and ice - fine-scale movements of a migratory arctic ungulate in the context of climate change.

    PubMed

    Leblond, Mathieu; St-Laurent, Martin-Hugues; Côté, Steeve D

    2016-01-01

    Freshwater lakes and rivers of the Northern Hemisphere have been freezing increasingly later and thawing increasingly earlier during the last century. With reduced temporal periods during which ice conditions are favourable for locomotion, freshwater bodies could become impediments to the inter-patch movements, dispersion, or migration of terrestrial animals that use ice-covered lakes and rivers to move across their range. Studying the fine-scale responses of individuals to broad-scale changes in ice availability and phenology would help to understand how animals react to ongoing climate change, and contribute to the conservation and management of endangered species living in northern environments. Between 2007 and 2014, we equipped 96 migratory caribou Rangifer tarandus caribou from the Rivière-aux-Feuilles herd in northern Québec (Canada) with GPS telemetry collars and studied their space use. We measured contemporary (digital MODIS maps updated every 8 days, 2000-2014) and historical (annual observations, 1947-1985) variations in freshwater-ice availability and evaluated the concurrent responses of caribou to these changes. Ice had a positive influence on caribou movement rates and directionality, and caribou selected ice and avoided water when moving across or in the vicinity of large water bodies. When ice was unavailable, caribou rarely swam across (6 % of crossings) and frequently circumvented water bodies for several km. Although ice phenology did not change significantly during our study, climate projections indicated that ice availability could decrease considerably before the end of the century, generating a ~28 % increase in distance travelled by caribou during the early spring and fall migrations. We demonstrated that ice availability influenced the movements of a migratory arctic ungulate. Warmer air temperatures in the Arctic will undoubtedly modify the phenology of ice forming on freshwater lakes and rivers. If migratory caribou are unable to

  14. Using fine-scale fuel measurements to assess wildland fuels, potential fire behavior and hazard mitigation treatments in the southeastern USA.

    SciTech Connect

    Ottmar, Roger, D.; Blake, John, I.; Crolly, William, T.

    2012-01-01

    The inherent spatial and temporal heterogeneity of fuelbeds in forests of the southeastern United States may require fine scale fuel measurements for providing reliable fire hazard and fuel treatment effectiveness estimates. In a series of five papers, an intensive, fine scale fuel inventory from the Savanna River Site in the southeastern United States is used for building fuelbeds and mapping fire behavior potential, evaluating fuel treatment options for effectiveness, and providing a comparative analysis of landscape modeled fire behavior using three different data sources including the Fuel Characteristic Classification System, LANDFIRE, and the Southern Wildfire Risk Assessment. The research demonstrates that fine scale fuel measurements associated with fuel inventories repeated over time can be used to assess broad scale wildland fire potential and hazard mitigation treatment effectiveness in the southeastern USA and similar fire prone regions. Additional investigations will be needed to modify and improve these processes and capture the true potential of these fine scale data sets for fire and fuel management planning.

  15. Mother–offspring distances reflect sex differences in fine-scale genetic structure of eastern grey kangaroos

    PubMed Central

    King, Wendy J; Garant, Dany; Festa-Bianchet, Marco

    2015-01-01

    Natal dispersal affects life history and population biology and causes gene flow. In mammals, dispersal is usually male-biased so that females tend to be philopatric and surrounded by matrilineal kin, which may lead to preferential associations among female kin. Here we combine genetic analyses and behavioral observations to investigate spatial genetic structure and sex-biased dispersal patterns in a high-density population of mammals showing fission–fusion group dynamics. We studied eastern grey kangaroos (Macropus giganteus) over 2 years at Wilsons Promontory National Park, Australia, and found weak fine-scale genetic structure among adult females in both years but no structure among adult males. Immature male kangaroos moved away from their mothers at 18–25 months of age, while immature females remained near their mothers until older. A higher proportion of male (34%) than female (6%) subadults and young adults were observed to disperse, although median distances of detected dispersals were similar for both sexes. Adult females had overlapping ranges that were far wider than the maximum extent of spatial genetic structure found. Female kangaroos, although weakly philopatric, mostly encounter nonrelatives in fission–fusion groups at high density, and therefore kinship is unlikely to strongly affect sociality. PMID:26045958

  16. Fine-scale habitat use of reintroduced black-footed ferrets on prairie dog colonies in New Mexico

    USGS Publications Warehouse

    Chipault, Jennifer G.; Biggins, Dean E.; Detling, James K.; Long, Dustin H.; Reich, Robin M.

    2012-01-01

    Black-footed ferrets (Mustela nigripes) are among the most endangered animals in North America. Reintroductions of captive-born ferrets onto prairie dog (Cynomys spp.) colonies are crucial to the conservation of the species. In September 2007, captive-born ferrets were released on a black-tailed prairie dog (Cynomys ludovicianus) colony at the Vermejo Park Ranch, New Mexico. Ferret kits experimentally released in areas of comparatively low and high prairie dog burrow densities were located via spotlight surveys. Some maturing ferret kits were subsequently translocated to areas of low and high burrow densities on nearby prairie dog colonies. For 2 months, fine-scale habitat use was quantified by mapping all burrow openings within a 30-m radius of each ferret location. Spatial statistics accounted for autocorrelation in the burrow densities in areas used by ferrets. It was hypothesized that ferrets would select areas of high burrow densities within colonies; however, burrow densities in areas used by ferrets were generally similar to the available burrow densities. Because ferrets used areas with burrow densities similar to densities available at the colony level and because of the potential energetic benefits for ferrets using areas with high burrow densities, releasing ferrets on colonies with high burrow densities might increase reintroduction success.

  17. Resource selection models are useful in predicting fine-scale distributions of black-footed ferrets in prairie dog colonies

    USGS Publications Warehouse

    Eads, David A.; Jachowski, David S.; Biggins, Dean E.; Livieri, Travis M.; Matchett, Marc R.; Millspaugh, Joshua J.

    2012-01-01

    Wildlife-habitat relationships are often conceptualized as resource selection functions (RSFs)—models increasingly used to estimate species distributions and prioritize habitat conservation. We evaluated the predictive capabilities of 2 black-footed ferret (Mustela nigripes) RSFs developed on a 452-ha colony of black-tailed prairie dogs (Cynomys ludovicianus) in the Conata Basin, South Dakota. We used the RSFs to project the relative probability of occurrence of ferrets throughout an adjacent 227-ha colony. We evaluated performance of the RSFs using ferret space use data collected via postbreeding spotlight surveys June–October 2005–2006. In home ranges and core areas, ferrets selected the predicted "very high" and "high" occurrence categories of both RSFs. Count metrics also suggested selection of these categories; for each model in each year, approximately 81% of ferret locations occurred in areas of very high or high predicted occurrence. These results suggest usefulness of the RSFs in estimating the distribution of ferrets throughout a black-tailed prairie dog colony. The RSFs provide a fine-scale habitat assessment for ferrets that can be used to prioritize releases of ferrets and habitat restoration for prairie dogs and ferrets. A method to quickly inventory the distribution of prairie dog burrow openings would greatly facilitate application of the RSFs.

  18. Fine-scale population structure of Malays in Peninsular Malaysia and Singapore and implications for association studies.

    PubMed

    Hoh, Boon-Peng; Deng, Lian; Julia-Ashazila, Mat Jusoh; Zuraihan, Zakaria; Nur-Hasnah, Ma'amor; Nur-Shafawati, Ab Rajab; Hatin, Wan Isa; Endom, Ismail; Zilfalil, Bin Alwi; Khalid, Yusoff; Xu, Shuhua

    2015-07-22

    Fine scale population structure of Malays - the major population in Malaysia, has not been well studied. This may have important implications for both evolutionary and medical studies. Here, we investigated the population sub-structure of Malay involving 431 samples collected from all states from peninsular Malaysia and Singapore. We identified two major clusters of individuals corresponding to the north and south peninsular Malaysia. On an even finer scale, the genetic coordinates of the geographical Malay populations are in correlation with the latitudes (R(2) = 0.3925; P = 0.029). This finding is further supported by the pairwise FST of Malay sub-populations, of which the north and south regions showed the highest differentiation (FST [North-south] = 0.0011). The collective findings therefore suggest that population sub-structure of Malays are more heterogenous than previously expected even within a small geographical region, possibly due to factors like different genetic origins, geographical isolation, could result in spurious association as demonstrated in our analysis. We suggest that cautions should be taken during the stage of study design or interpreting the association signals in disease mapping studies which are expected to be conducted in Malay population in the near future.

  19. Significant demographic and fine-scale genetic structure in expanding and senescing populations of the terrestrial orchid Cymbidium goeringii (Orchidaceae).

    PubMed

    Chung, Mi Yoon; Nason, John D; Chung, Myong Gi

    2011-12-01

    Fine-scale genetic structure (FSGS) in plants is influenced by variation in spatial and temporal demographic processes. To determine how demographic structure and FSGS change with stages of population succession, we studied replicate expanding and senescing populations of the Asian terrestrial orchid Cymbidium goeringii. We used spatial autocorrelation methods (O-ring and kinship statistics) to quantify spatial demographic structure and FSGS in two expanding and two senescing populations, also measuring genetic diversity and inbreeding in each. All populations exhibited significant aggregation of individuals and FSGS at short spatial scales. In expanding populations, this finding was associated with high recruitment rates, suggesting restricted seed dispersal. In senescing populations, recruitment was minimal, suggesting alternative mechanisms of aggregation, perhaps including spatial associations with mycorrhizal fungi. All populations had significant evidence of genetic bottlenecks, and inbreeding levels were consistently high. Our results indicate that different successional stages can generate similar patterns of spatial demographic and genetic structure, but as a consequence of different processes. These results contrast with the only other study of senescence effects on population genetic structure in an herbaceous perennial, which found little to no FSGS in senescing populations. With the exception of populations subject to mass collection by orchid sellers, significant FSGS is characteristic of the 16 terrestrial orchid species examined to date. From a conservation perspective, this result suggests that inference of orchid population history will benefit from analyses of both FSGS and demographic structure in combination with other ecological field data.

  20. Fine-Scale Ecological and Genetic Population Structure of Two Whitefish (Coregoninae) Species in the Vicinity of Industrial Thermal Emissions.

    PubMed

    Graham, Carly F; Eberts, Rebecca L; Morgan, Thomas D; Boreham, Douglas R; Lance, Stacey L; Manzon, Richard G; Martino, Jessica A; Rogers, Sean M; Wilson, Joanna Y; Somers, Christopher M

    2016-01-01

    Thermal pollution from industrial processes can have negative impacts on the spawning and development of cold-water fish. Point sources of thermal effluent may need to be managed to avoid affecting discrete populations. Correspondingly, we examined fine-scale ecological and genetic population structure of two whitefish species (Coregonus clupeaformis and Prosopium cylindraceum) on Lake Huron, Canada, in the immediate vicinity of thermal effluent from nuclear power generation. Niche metrics using δ13C and δ15N stable isotopes showed high levels of overlap (48.6 to 94.5%) in resource use by adult fish captured in areas affected by thermal effluent compared to nearby reference locations. Isotopic niche size, a metric of resource use diversity, was 1.3- to 2.8-fold higher than reference values in some thermally affected areas, indicative of fish mixing. Microsatellite analyses of genetic population structure (Fst, STRUCTURE and DAPC) indicated that fish captured at all locations in the vicinity of the power plant were part of a larger population extending beyond the study area. In concert, ecological and genetic markers do not support the presence of an evolutionarily significant unit in the vicinity of the power plant. Thus, future research should focus on the potential impacts of thermal emissions on development and recruitment.

  1. Fine-scale ecological and genetic population structure of two whitefish (Coregoninae) species in the vicinity of industrial thermal emissions

    SciTech Connect

    Graham, Carly F.; Eberts, Rebecca L.; Morgan, Thomas D.; Boreham, Douglas R.; Lance, Stacey L.; Manzon, Richard G.; Martino, Jessica A.; Rogers, Sean M.; Wilson, Joanna Y.; Somers, Christopher M.; Britton, Robert

    2016-01-25

    Thermal pollution from industrial processes can have negative impacts on the spawning and development of cold-water fish. Point sources of thermal effluent may need to be managed to avoid affecting discrete populations. Correspondingly, we examined fine-scale ecological and genetic population structure of two whitefish species (Coregonus clupeaformis and Prosopium cylindraceum) on Lake Huron, Canada, in the immediate vicinity of thermal effluent from nuclear power generation. Niche metrics using δ13C and δ15N stable isotopes showed high levels of overlap (48.6 to 94.5%) in resource use by adult fish captured in areas affected by thermal effluent compared to nearby reference locations. Isotopic niche size, a metric of resource use diversity, was 1.3- to 2.8-fold higher than reference values in some thermally affected areas, indicative of fish mixing. Microsatellite analyses of genetic population structure (Fst, STRUCTURE and DAPC) indicated that fish captured at all locations in the vicinity of the power plant were part of a larger population extending beyond the study area. In concert, ecological and genetic markers do not support the presence of an evolutionarily significant unit in the vicinity of the power plant. Furthermore, future research should focus on the potential impacts of thermal emissions on development and recruitment.

  2. Fine-scale ecological and genetic population structure of two whitefish (Coregoninae) species in the vicinity of industrial thermal emissions

    DOE PAGES

    Graham, Carly F.; Eberts, Rebecca L.; Morgan, Thomas D.; ...

    2016-01-25

    Thermal pollution from industrial processes can have negative impacts on the spawning and development of cold-water fish. Point sources of thermal effluent may need to be managed to avoid affecting discrete populations. Correspondingly, we examined fine-scale ecological and genetic population structure of two whitefish species (Coregonus clupeaformis and Prosopium cylindraceum) on Lake Huron, Canada, in the immediate vicinity of thermal effluent from nuclear power generation. Niche metrics using δ13C and δ15N stable isotopes showed high levels of overlap (48.6 to 94.5%) in resource use by adult fish captured in areas affected by thermal effluent compared to nearby reference locations. Isotopicmore » niche size, a metric of resource use diversity, was 1.3- to 2.8-fold higher than reference values in some thermally affected areas, indicative of fish mixing. Microsatellite analyses of genetic population structure (Fst, STRUCTURE and DAPC) indicated that fish captured at all locations in the vicinity of the power plant were part of a larger population extending beyond the study area. In concert, ecological and genetic markers do not support the presence of an evolutionarily significant unit in the vicinity of the power plant. Furthermore, future research should focus on the potential impacts of thermal emissions on development and recruitment.« less

  3. Fine-scale chromatin interaction maps reveal the cis-regulatory landscape of human lincRNA genes

    PubMed Central

    Ma, Wenxiu; Ay, Ferhat; Lee, Choli; Gulsoy, Gunhan; Deng, Xinxian; Cook, Savannah; Hesson, Jennifer; Cavanaugh, Christopher; Ware, Carol B.; Krumm, Anton; Shendure, Jay; Blau, C. Anthony; Disteche, Christine M.; Noble, William S.; Duan, ZhiJun

    2014-01-01

    High-throughput methods based on chromosome conformation capture (3C) have greatly advanced our understanding of the three-dimensional (3D) organization of genomes but are limited in resolution by their reliance on restriction enzymes (REs). Here we describe a method called DNase Hi-C for comprehensively mapping global chromatin contacts that uses DNase I for chromatin fragmentation, leading to greatly improved efficiency and resolution compared to Hi-C. Coupling this method with DNA capture technology provides a high-throughput approach for targeted mapping of fine-scale chromatin architecture. We applied targeted DNase Hi-C to characterize the 3D organization of 998 lincRNA (long intergenic noncoding RNA) promoters in two human cell lines, thereby revealing that expression of lincRNAs is tightly controlled by complex mechanisms involving both super-enhancers and the polycomb repressive complex. Our results provide the first glimpse of a cell type-specific 3D organization of lincRNA genes. PMID:25437436

  4. From fine-scale foraging to home ranges: a semivariance approach to identifying movement modes across spatiotemporal scales.

    PubMed

    Fleming, Chris H; Calabrese, Justin M; Mueller, Thomas; Olson, Kirk A; Leimgruber, Peter; Fagan, William F

    2014-05-01

    Understanding animal movement is a key challenge in ecology and conservation biology. Relocation data often represent a complex mixture of different movement behaviors, and reliably decomposing this mix into its component parts is an unresolved problem in movement ecology. Traditional approaches, such as composite random walk models, require that the timescales characterizing the movement are all similar to the usually arbitrary data-sampling rate. Movement behaviors such as long-distance searching and fine-scale foraging, however, are often intermixed but operate on vastly different spatial and temporal scales. An approach that integrates the full sweep of movement behaviors across scales is currently lacking. Here we show how the semivariance function (SVF) of a stochastic movement process can both identify multiple movement modes and solve the sampling rate problem. We express a broad range of continuous-space, continuous-time stochastic movement models in terms of their SVFs, connect them to relocation data via variogram regression, and compare them using standard model selection techniques. We illustrate our approach using Mongolian gazelle relocation data and show that gazelle movement is characterized by ballistic foraging movements on a 6-h timescale, fast diffusive searching with a 10-week timescale, and asymptotic diffusion over longer timescales.

  5. Extensive cryptic species diversity and fine-scale endemism in the marine red alga Portieria in the Philippines.

    PubMed

    Payo, Dioli Ann; Leliaert, Frederik; Verbruggen, Heroen; D'hondt, Sofie; Calumpong, Hilconida P; De Clerck, Olivier

    2013-02-22

    We investigated species diversity and distribution patterns of the marine red alga Portieria in the Philippine archipelago. Species boundaries were tested based on mitochondrial, plastid and nuclear encoded loci, using a general mixed Yule-coalescent (GMYC) model-based approach and a bayesian multilocus species delimitation method. The outcome of the GMYC analysis of the mitochondrial encoded cox2-3 dataset was highly congruent with the multilocus analysis. In stark contrast with the current morphology-based assumption that the genus includes a single, widely distributed species in the Indo-West Pacific (Portieria hornemannii), DNA-based species delimitation resulted in the recognition of 21 species within the Philippines. Species distributions were found to be highly structured with most species restricted to island groups within the archipelago. These extremely narrow species ranges and high levels of intra-archipelagic endemism contrast with the wide-held belief that marine organisms generally have large geographical ranges and that endemism is at most restricted to the archipelagic level. Our results indicate that speciation in the marine environment may occur at spatial scales smaller than 100 km, comparable with some terrestrial systems. Our finding of fine-scale endemism has important consequences for marine conservation and management.

  6. Extensive cryptic species diversity and fine-scale endemism in the marine red alga Portieria in the Philippines

    PubMed Central

    Payo, Dioli Ann; Leliaert, Frederik; Verbruggen, Heroen; D'hondt, Sofie; Calumpong, Hilconida P.; De Clerck, Olivier

    2013-01-01

    We investigated species diversity and distribution patterns of the marine red alga Portieria in the Philippine archipelago. Species boundaries were tested based on mitochondrial, plastid and nuclear encoded loci, using a general mixed Yule-coalescent (GMYC) model-based approach and a Bayesian multilocus species delimitation method. The outcome of the GMYC analysis of the mitochondrial encoded cox2-3 dataset was highly congruent with the multilocus analysis. In stark contrast with the current morphology-based assumption that the genus includes a single, widely distributed species in the Indo-West Pacific (Portieria hornemannii), DNA-based species delimitation resulted in the recognition of 21 species within the Philippines. Species distributions were found to be highly structured with most species restricted to island groups within the archipelago. These extremely narrow species ranges and high levels of intra-archipelagic endemism contrast with the wide-held belief that marine organisms generally have large geographical ranges and that endemism is at most restricted to the archipelagic level. Our results indicate that speciation in the marine environment may occur at spatial scales smaller than 100 km, comparable with some terrestrial systems. Our finding of fine-scale endemism has important consequences for marine conservation and management. PMID:23269854

  7. Fine-Scale Topographic Analysis of Rock Size Distributions Derived from High-Resolution Ground-Based LiDAR

    NASA Astrophysics Data System (ADS)

    Finnegan, D. C.; Arcone, S. A.; Bulmer, M. H.; Anderson, S. W.

    2007-05-01

    Quantitative factors such as RMS height, correlation lengths and surface slope derived from fine-scale topographic datasets hold the potential for characterizing surface morphology in relation to its underlying geologic processes. In an attempt to better understand the relationships between topographic roughness characteristics and geologic processes responsible for creating a distinct surface morphology, we utilize ground-based terrestrial LiDAR and coincidental orthorectified imagery to quantify the variability in RMS heights and correlation lengths. The purpose of this study is to understand directly how various topographic data collection techniques such as LiDAR and manual field-based measurements compare to one another and which techniques are most appropriate for characterizing topography at various scales. Topographic data from several platforms were acquired over desert surfaces in the Mojave Desert near Palm Springs, California and southwestern Arizona. The desert surfaces imaged in the Mojave contained average rock sizes ranging from decimeters to a maximum size near one meter and revealed wide variations in RMS heights and correlation lengths, in keeping with the highly variable surface. Alternately, the Arizona site exhibits less topographic variability and consistent statistics. The data are useful for characterizing the roughness of surfaces for a variety of disciplines, such as penetration of remote sensing signals, upwelling of radiation and characterizing the genetic origin of surfaces. Furthermore, these data become essential to airborne and ground-based imaging sensors and understanding how topographic irregularities affect data fidelity.

  8. The fate of priority areas for conservation in protected areas: a fine-scale Markov chain approach.

    PubMed

    Tattoni, Clara; Ciolli, Marco; Ferretti, Fabrizio

    2011-02-01

    Park managers in alpine areas must deal with the increase in forest coverage that has been observed in most European mountain areas, where traditional farming and agricultural practices have been abandoned. The aim of this study is to develop a fine-scale model of a broad area to support the managers of Paneveggio Nature Park (Italy) in conservation planning by focusing on the fate of priority areas for conservation in the next 50-100 years. GIS analyses were performed to assess the afforestation dynamic over time using two historical maps (from 1859 and 1936) and a series of aerial photographs and ortho-photos (taken from 1954 to 2006) covering a time span of 150 years. The results show an increase in the forest surface area of about 35%. Additionally, the forest became progressively more compact and less fragmented, with a consequent loss of ecotones and open habitats that are important for biodiversity. Markov chain-cellular automata models were used to project future changes, evaluating the effects on a habitat scale. Simulations show that some habitats defined as priority by the EU Habitat Directive will be compromised by the forest expansion by 2050 and suffer a consistent loss by 2100. This protocol, applied to other areas, can be used for designing long-term management measures with a focus on habitats where conservation status is at risk.

  9. Fine-scale spatial distribution of orchid mycorrhizal fungi in the soil of host-rich grasslands.

    PubMed

    Voyron, Samuele; Ercole, Enrico; Ghignone, Stefano; Perotto, Silvia; Girlanda, Mariangela

    2017-02-01

    Mycorrhizal fungi are essential for the survival of orchid seedlings under natural conditions. The distribution of these fungi in soil can constrain the establishment and resulting spatial arrangement of orchids at the local scale, but the actual extent of occurrence and spatial patterns of orchid mycorrhizal (OrM) fungi in soil remain largely unknown. We addressed the fine-scale spatial distribution of OrM fungi in two orchid-rich Mediterranean grasslands by means of high-throughput sequencing of fungal ITS2 amplicons, obtained from soil samples collected either directly beneath or at a distance from adult Anacamptis morio and Ophrys sphegodes plants. Like ectomycorrhizal and arbuscular mycobionts, OrM fungi (tulasnelloid, ceratobasidioid, sebacinoid and pezizoid fungi) exhibited significant horizontal spatial autocorrelation in soil. However, OrM fungal read numbers did not correlate with distance from adult orchid plants, and several of these fungi were extremely sporadic or undetected even in the soil samples containing the orchid roots. Orchid mycorrhizal 'rhizoctonias' are commonly regarded as unspecialized saprotrophs. The sporadic occurrence of mycobionts of grassland orchids in host-rich stands questions the view of these mycorrhizal fungi as capable of sustained growth in soil.

  10. Fine-Scale Genetic Structure and Gene Dispersal in Centaurea corymbosa (Asteraceae). II. Correlated Paternity Within and Among Sibships

    PubMed Central

    Hardy, Olivier J.; González-Martínez, Santiago C.; Colas, Bruno; Fréville, Hélène; Mignot, Agnès; Olivieri, Isabelle

    2004-01-01

    The fine-scale pattern of correlated paternity was characterized within a population of the narrow-endemic model plant species, Centaurea corymbosa, using microsatellites and natural progeny arrays. We used classical approaches to assess correlated mating within sibships and developed a new method based on pairwise kinship coefficients to assess correlated paternity within and among sibships in a spatio-temporal perspective. We also performed numerical simulations to assess the relative significance of different mechanisms promoting correlated paternity and to compare the statistical properties of different estimators of correlated paternity. Our new approach proved very informative to assess which factors contributed most to correlated paternity and presented good statistical properties. Within progeny arrays, we found that about one-fifth of offspring pairs were full-sibs. This level of correlated mating did not result from correlated pollen dispersal events (i.e., pollen codispersion) but rather from limited mate availability, the latter being due to limited pollen dispersal distances, the heterogeneity of pollen production among plants, phenological heterogeneity and, according to simulations, the self-incompatibility system. We point out the close connection between correlated paternity and the “TwoGener” approach recently developed to infer pollen dispersal and discuss the conditions to be met when applying the latter. PMID:15579710

  11. Cultural transmission of tool use combined with habitat specializations leads to fine-scale genetic structure in bottlenose dolphins.

    PubMed

    Kopps, Anna M; Ackermann, Corinne Y; Sherwin, William B; Allen, Simon J; Bejder, Lars; Krützen, Michael

    2014-05-07

    Socially learned behaviours leading to genetic population structure have rarely been described outside humans. Here, we provide evidence of fine-scale genetic structure that has probably arisen based on socially transmitted behaviours in bottlenose dolphins (Tursiops sp.) in western Shark Bay, Western Australia. We argue that vertical social transmission in different habitats has led to significant geographical genetic structure of mitochondrial DNA (mtDNA) haplotypes. Dolphins with mtDNA haplotypes E or F are found predominantly in deep (more than 10 m) channel habitat, while dolphins with a third haplotype (H) are found predominantly in shallow habitat (less than 10 m), indicating a strong haplotype-habitat correlation. Some dolphins in the deep habitat engage in a foraging strategy using tools. These 'sponging' dolphins are members of one matriline, carrying haplotype E. This pattern is consistent with what had been demonstrated previously at another research site in Shark Bay, where vertical social transmission of sponging had been shown using multiple lines of evidence. Using an individual-based model, we found support that in western Shark Bay, socially transmitted specializations may have led to the observed genetic structure. The reported genetic structure appears to present an example of cultural hitchhiking of mtDNA haplotypes on socially transmitted foraging strategies, suggesting that, as in humans, genetic structure can be shaped through cultural transmission.

  12. Fine-scale planktonic habitat partitioning at a shelf-slope front revealed by a high-resolution imaging system

    NASA Astrophysics Data System (ADS)

    Greer, Adam T.; Cowen, Robert K.; Guigand, Cedric M.; Hare, Jonathan A.

    2015-02-01

    Ocean fronts represent productive regions of the ocean, but predator-prey interactions within these features are poorly understood partially due to the coarse-scale and biases of net-based sampling methods. We used the In Situ Ichthyoplankton Imaging System (ISIIS) to sample across a front near the Georges Bank shelf edge on two separate sampling days in August 2010. Salinity characterized the transition from shelf to slope water, with isopycnals sloping vertically, seaward, and shoaling at the thermocline. A frontal feature defined by the convergence of isopycnals and a surface temperature gradient was sampled inshore of the shallowest zone of the shelf-slope front. Zooplankton and larval fishes were abundant on the shelf side of the front and displayed taxon-dependent depth distributions but were rare in the slope waters. Supervised automated particle counting showed small particles with high solidity, verified to be zooplankton (copepods and appendicularians), aggregating near surface above the front. Salps were most abundant in zones of intermediate chlorophyll-a fluorescence, distinctly separate from high abundances of other grazers and found almost exclusively in colonial form (97.5%). Distributions of gelatinous zooplankton differed among taxa but tended to follow isopycnals. Fine-scale sampling revealed distinct habitat partitioning of various planktonic taxa, resulting from a balance of physical and biological drivers in relation to the front.

  13. Impact of soil matric potential on the fine-scale spatial distribution and activity of specific microbial degrader communities.

    PubMed

    Monard, Cécile; Mchergui, Chokri; Nunan, Naoise; Martin-Laurent, Fabrice; Vieublé-Gonod, Laure

    2012-09-01

    The impact of the soil matric potential on the relationship between the relative abundance of degraders and their activity and on the spatial distribution of both at fine scales was determined to understand the role of environmental conditions in the degradation of organic substrates. The mineralization of (13) C-glucose and (13) C-2,4-dichlorophenoxyacetic acid (2,4-D) was measured at different matric potentials (-0.001, -0.01 and -0.316 MPa) in 6 × 6 × 6 mm(3) cubes excised from soil cores. At the end of the incubation, total bacterial and 2,4-D degrader abundances were determined by quantifying the 16S rRNA and the tfdA genes, respectively. The mineralization of 2,4-D was more sensitive to changes in matric potential than was that of glucose. The amount and spatial structure of 2,4-D mineralization decreased with matric potential, whilst the spatial variability increased. On the other hand, the spatial variation of glucose mineralization was less affected by changes in matric potential. The relationship between the relative abundance of 2,4-D degraders and 2,4-D mineralization was significantly affected by matric potential: the relative abundance of tfdA needed to be higher to reach a given level of 2,4-D mineralization in dryer than in moister conditions. The data show how microbial interactions with their microhabitat can have an impact on soil processes at larger scales.

  14. Coral habitat in the Aleutian Islands of Alaska: depth distribution, fine-scale species associations, and fisheries interactions

    NASA Astrophysics Data System (ADS)

    Stone, R. P.

    2006-05-01

    The first in situ exploration of Aleutian Island coral habitat was completed in 2002 to determine the distribution of corals, to examine fine-scale associations between targeted fish species and corals, and to investigate the interaction between the areas’ diverse fisheries and coral habitat. Corals, mostly gorgonians and hydrocorals, were present on all 25 seafloor transects and at depths between 27 and 363 m, but were most abundant between 100 and 200 m depth. Mean coral abundance (1.23 colonies m-2) far exceeded that reported for other high-latitude ecosystems and high-density coral gardens (3.85 colonies m-2) were observed at seven locations. Slope and offshore pinnacle habitats characterized by exposed bedrock, boulders, and cobbles generally supported the highest abundances of coral and fish. Overall, 85% of the economically important fish species observed on transects were associated with corals and other emergent epifauna. Disturbance to the seafloor from bottom-contact fishing gear was evident on 88% of the transects, and approximately 39% of the total area of the seafloor observed had been disturbed. Since cold-water corals appear to be a ubiquitous feature of seafloor habitats in the Aleutian Islands, fisheries managers face clear challenges integrating coral conservation into an ecosystem approach to fisheries management.

  15. Cultural transmission of tool use combined with habitat specializations leads to fine-scale genetic structure in bottlenose dolphins

    PubMed Central

    Kopps, Anna M.; Ackermann, Corinne Y.; Sherwin, William B.; Allen, Simon J.; Bejder, Lars; Krützen, Michael

    2014-01-01

    Socially learned behaviours leading to genetic population structure have rarely been described outside humans. Here, we provide evidence of fine-scale genetic structure that has probably arisen based on socially transmitted behaviours in bottlenose dolphins (Tursiops sp.) in western Shark Bay, Western Australia. We argue that vertical social transmission in different habitats has led to significant geographical genetic structure of mitochondrial DNA (mtDNA) haplotypes. Dolphins with mtDNA haplotypes E or F are found predominantly in deep (more than 10 m) channel habitat, while dolphins with a third haplotype (H) are found predominantly in shallow habitat (less than 10 m), indicating a strong haplotype–habitat correlation. Some dolphins in the deep habitat engage in a foraging strategy using tools. These ‘sponging’ dolphins are members of one matriline, carrying haplotype E. This pattern is consistent with what had been demonstrated previously at another research site in Shark Bay, where vertical social transmission of sponging had been shown using multiple lines of evidence. Using an individual-based model, we found support that in western Shark Bay, socially transmitted specializations may have led to the observed genetic structure. The reported genetic structure appears to present an example of cultural hitchhiking of mtDNA haplotypes on socially transmitted foraging strategies, suggesting that, as in humans, genetic structure can be shaped through cultural transmission. PMID:24648223

  16. Color-Biased Dispersal Inferred by Fine-Scale Genetic Spatial Autocorrelation in a Color Polymorphic Salamander.

    PubMed

    Grant, Alexa H; Liebgold, Eric B

    2017-07-01

    Behavioral traits can be influenced by predation rates of color morphs, potentially leading to reduced boldness or increased escape behaviors in one color morph. The red-backed salamander, Plethodon cinereus, is a small terrestrial salamander whose color morphs have different diets and select different microhabitats, but little is known about potential differences in dispersal behaviors. We used fine-scale genetic spatial autocorrelation to examine 122 P. cinereus in a color-polymorphic population at 10 microsatellite loci in order to generate estimates of spatial genetic structure for each color morph. Differences in spatial genetic structure have been used extensively to infer within-population sex-biased dispersal but have never been used to test for dispersal differences between other groups within populations such as color morphs. We found evidence for color-biased dispersal, but not sex-biased dispersal. Striped salamanders had significant positive genetic structure in the shortest distance classes indicating philopatry. In contrast, unstriped salamanders showed a lack of spatial genetic structure at shorter distances and higher than expected genetic similarity at further distances, as expected if they are dispersing from their natal site. These results show that genetic methods typically used for sex-biased dispersal can be used to investigate differences in dispersal between morphs that vary discretely in polymorphic populations, such as color morphs. © The American Genetic Association 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  17. Fine-scale spatial genetic structure analysis of the black truffle Tuber aestivum and its link to aroma variability.

    PubMed

    Molinier, Virginie; Murat, Claude; Frochot, Henri; Wipf, Daniel; Splivallo, Richard

    2015-08-01

    Truffles are symbiotic fungi in high demand by food connoisseurs. Improving yield and product quality requires a better understanding of truffle genetics and aroma biosynthesis. One aim here was to investigate the diversity and fine-scale spatial genetic structure of the Burgundy truffle Tuber aestivum. The second aim was to assess how genetic structuring along with fruiting body maturation and geographical origin influenced single constituents of truffle aroma. A total of 39 Burgundy truffles collected in two orchards were characterized in terms of aroma profile (SPME-GC/MS) and genotype (microsatellites). A moderate genetic differentiation was observed between the populations of the two orchards. An important seasonal and spatial genetic structuring was detected. Within one orchard, individuals belonging to the same genet were generally collected during a single season and in the close vicinity from each other. Maximum genet size nevertheless ranged from 46 to 92 m. Geographical origin or maturity only had minor effects on aroma profiles but genetic structuring, specifically clonal identity, had a pronounced influence on the concentrations of C8 - and C4 -VOCs. Our results highlight a high seasonal genetic turnover and indicate that the aroma of Burgundy truffle is influenced by the identity of single clones/genets. © 2015 Society for Applied Microbiology and John Wiley & Sons Ltd.

  18. Fine scale variability of hyporheic hydrochemistry in salmon spawning gravels with contrasting groundwater-surface water interactions

    NASA Astrophysics Data System (ADS)

    Malcolm, I. A.; Soulsby, C.; Youngson, A. F.; Tetzlaff, D.

    2009-02-01

    There is increasing realisation of the importance of groundwater-surface water (GW-SW) interactions in understanding freshwater ecology. A study that assessed the influence of local GW-SW interactions on shallow (<250 mm) hyporheic water quality at two contrasting salmon spawning locations in Scotland, UK is reported. At a groundwater-dominated site, continuous logging sensors revealed that hyporheic dissolved oxygen (DO) concentrations changed rapidly in response to changing hydrological conditions. Low volume (25 ml) spot samples revealed fine-scale spatial variability (<0.05 m) consistent with a vertically shifting boundary layer between source waters. At a surface-water-dominated location, hyporheic water was typically characterised by high DO and electrical conductivity values, characteristic of surface water. Small reductions in DO at this site are hypothesised to be associated with short residence hyporheic discharge. A comparison between in-situ (logging DO sensor data) and ex-situ (small volume sampling) methods revealed good agreement, potentially allowing deployment of the two methods in stratified sampling programmes. This study demonstrates that hyporheic water quality varies over fine spatial and temporal scales and that future studies need to design sampling strategies that consider the scales appropriate to both the ecology and the hyporheic processes of interest.

  19. A comparison of the fine-scale structure of the diurnal cycle of tropical rain and lightning

    NASA Astrophysics Data System (ADS)

    Venugopal, V.; Virts, K.; Sukhatme, J.; Wallace, J. M.; Chattopadhyay, B.

    2016-03-01

    In this study, the fine-scale structure of the diurnal variability of ground-based lightning is systematically compared with satellite-based rain. At the outset, it is shown that tropical variability of lightning exhibits a prominent diurnal mode, much like rain. A comparison of the geographical distribution of the timing of the diurnal maximum shows that there is very good agreement between the two observables over continental and coastal regions throughout the tropics. Following this global tropical comparison, we focus on two regions, Borneo and equatorial South America, both of which show the interplay between oceanward and landward propagations of the phase of the diurnal maximum. Over Borneo, both rain and lightning clearly show a climatological cycle of "breathing in" (afternoon to early morning) and "breathing out" (morning to early afternoon). Over the equatorial east coast of South America, landward propagation is noticed in rain and lightning from early afternoon to early morning. Along the Pacific coast of South America, both rain and lightning show oceanward propagation. Though qualitatively consistent, over both regions the propagation is seen to extend further in rainfall. Additionally, given that lightning highlights vigorous convection, the timing of its diurnal maximum often precedes that of rainfall in the convective life cycle.

  20. Fine-scale habitat preference of green sturgeon (Acipenser medirostris) within three spawning locations in the Sacramento River, California

    USGS Publications Warehouse

    Wyman, Megan T.; Thomas, Michael J.; McDonald, Richard R.; Hearn, Alexander R.; Battleson, Ryan D.; Chapman, Eric D.; Kinzel, Paul J.; Minear, J. Tobey; Mora, Ethan A.; Nelson, Jonathan M.; Pagel, Matthew D.; Klimley, A. Peter

    2017-01-01

    Vast sections of the Sacramento River have been listed as critical habitat by the National Marine Fisheries Service for green sturgeon spawning (Acipenser medirostris), yet spawning is known to occur at only a few specific locations. This study reveals the range of physical habitat variables selected by adult green sturgeon during their spawning period. We integrated fine-scale fish positions, physical habitat characteristics, discharge, bathymetry, and simulated velocity and depth using a 2-dimensional hydraulic model (FaSTMECH). The objective was to create habitat suitability curves for depth, velocity, and substrate type within three known spawning locations over two years. An overall cumulative habitat suitability score was calculated that averaged the depth, velocity, and substrate scores over all fish, sites, and years. A weighted usable area (WUA) index was calculated throughout the sampling periods for each of the three sites. Cumulative results indicate that the microhabitat characteristics most preferred by green sturgeon in these three spawning locations were velocities between 1.0-1.1 m/s, depths of 8-9 m, and gravel and sand substrate. This study provides guidance for those who may in the future want to increase spawning habitat for green sturgeon within the Sacramento River.

  1. Fine-scale kin recognition in the absence of social familiarity in the Siberian jay, a monogamous bird species.

    PubMed

    Griesser, Michael; Halvarsson, Peter; Drobniak, Szymon M; Vilà, Carles

    2015-11-01

    Kin recognition is a critical element to kin cooperation, and in vertebrates, it is primarily based on associative learning. Recognition of socially unfamiliar kin occurs rarely, and it is reported only in vertebrate species where promiscuity prevents recognition of first-order relatives. However, it is unknown whether the recognition of socially unfamiliar kin can evolve in monogamous species. Here, we investigate whether genetic relatedness modulates aggression among group members in Siberian jays (Perisoreus infaustus). This bird species is genetically and socially monogamous and lives in groups that are formed through the retention of offspring beyond independence, and the immigration of socially unfamiliar nonbreeders. Observations on feeders showed that genetic relatedness modulated aggression of breeders towards immigrants in a graded manner, in that they chased most intensely the immigrant group members that were genetically the least related. However, cross-fostering experiments showed that breeders were equally tolerant towards their own and cross-fostered young swapped as nestlings. Thus, breeders seem to use different mechanisms to recognize socially unfamiliar individuals and own offspring. As Siberian jays show a high degree of nepotism during foraging and predator encounters, inclusive fitness benefits may play a role for the evolution of fine-scale kin recognition. More generally, our results suggest that fine-graded kin recognition can evolve independently of social familiarity, highlighting the evolutionary importance of kin recognition for social species.

  2. Fine-Scale Heterogeneity in Crossover Rate in the garnet-scalloped Region of the Drosophila melanogaster X Chromosome

    PubMed Central

    Singh, Nadia D.; Stone, Eric A.; Aquadro, Charles F.; Clark, Andrew G.

    2013-01-01

    Homologous recombination affects myriad aspects of genome evolution, from standing levels of nucleotide diversity to the efficacy of natural selection. Rates of crossing over show marked variability at all scales surveyed, including species-, population-, and individual-level differences. Even within genomes, crossovers are nonrandomly distributed in a wide diversity of taxa. Although intra- and intergenomic heterogeneities in crossover distribution have been documented in Drosophila, the scale and degree of crossover rate heterogeneity remain unclear. In addition, the genetic features mediating this heterogeneity are unknown. Here we quantify fine-scale heterogeneity in crossover distribution in a 2.1-Mb region of the Drosophila melanogaster X chromosome by localizing crossover breakpoints in 2500 individuals, each containing a single crossover in this specific X chromosome region. We show 90-fold variation in rates of crossing over at a 5-kb scale, place this variation in the context of several aspects of genome evolution, and identify several genetic features associated with crossover rates. Our results shed new light on the scale and magnitude of crossover rate heterogeneity in D. melanogaster and highlight potential features mediating this heterogeneity. PMID:23410829

  3. Fine-Scale Ecological and Genetic Population Structure of Two Whitefish (Coregoninae) Species in the Vicinity of Industrial Thermal Emissions

    PubMed Central

    Graham, Carly F.; Eberts, Rebecca L.; Morgan, Thomas D.; Boreham, Douglas R.; Lance, Stacey L.; Manzon, Richard G.; Martino, Jessica A.; Rogers, Sean M.; Wilson, Joanna Y.; Somers, Christopher M.

    2016-01-01

    Thermal pollution from industrial processes can have negative impacts on the spawning and development of cold-water fish. Point sources of thermal effluent may need to be managed to avoid affecting discrete populations. Correspondingly, we examined fine-scale ecological and genetic population structure of two whitefish species (Coregonus clupeaformis and Prosopium cylindraceum) on Lake Huron, Canada, in the immediate vicinity of thermal effluent from nuclear power generation. Niche metrics using δ13C and δ15N stable isotopes showed high levels of overlap (48.6 to 94.5%) in resource use by adult fish captured in areas affected by thermal effluent compared to nearby reference locations. Isotopic niche size, a metric of resource use diversity, was 1.3- to 2.8-fold higher than reference values in some thermally affected areas, indicative of fish mixing. Microsatellite analyses of genetic population structure (Fst, STRUCTURE and DAPC) indicated that fish captured at all locations in the vicinity of the power plant were part of a larger population extending beyond the study area. In concert, ecological and genetic markers do not support the presence of an evolutionarily significant unit in the vicinity of the power plant. Thus, future research should focus on the potential impacts of thermal emissions on development and recruitment. PMID:26807722

  4. The Fate of Priority Areas for Conservation in Protected Areas: A Fine-Scale Markov Chain Approach

    NASA Astrophysics Data System (ADS)

    Tattoni, Clara; Ciolli, Marco; Ferretti, Fabrizio

    2011-02-01

    Park managers in alpine areas must deal with the increase in forest coverage that has been observed in most European mountain areas, where traditional farming and agricultural practices have been abandoned. The aim of this study is to develop a fine-scale model of a broad area to support the managers of Paneveggio Nature Park (Italy) in conservation planning by focusing on the fate of priority areas for conservation in the next 50-100 years. GIS analyses were performed to assess the afforestation dynamic over time using two historical maps (from 1859 and 1936) and a series of aerial photographs and ortho-photos (taken from 1954 to 2006) covering a time span of 150 years. The results show an increase in the forest surface area of about 35%. Additionally, the forest became progressively more compact and less fragmented, with a consequent loss of ecotones and open habitats that are important for biodiversity. Markov chain-cellular automata models were used to project future changes, evaluating the effects on a habitat scale. Simulations show that some habitats defined as priority by the EU Habitat Directive will be compromised by the forest expansion by 2050 and suffer a consistent loss by 2100. This protocol, applied to other areas, can be used for designing long-term management measures with a focus on habitats where conservation status is at risk.

  5. Fine-scale distribution of ectomycorrhizal fungi colonizing Tsuga diversifolia seedlings growing on rocks in a subalpine Abies veitchii forest.

    PubMed

    Yoshida, Naohiro; Son, Joung A; Matsushita, Norihisa; Iwamoto, Kojiro; Hogetsu, Taizo

    2014-05-01

    Numerous species of ectomycorrhizal (ECM) fungi coexist under the forest floor. To explore the mechanisms of coexistence, we investigated the fine-scale distribution of ECM fungal species colonizing root tips in the root system of Tsuga diversifolia seedlings in a subalpine forest. ECM root tips of three seedlings growing on the flat top surface of rocks were sampled after recording their positions in the root system. After the root tips were grouped by terminal-restriction fragment length polymorphism (T-RFLP) analysis of ITS rDNA, the fungal species representing each T-RFLP group were identified using DNA sequencing. Based on the fungal species identification, the distribution of root tips colonized by each ECM fungus was mapped. Significant clustering of root tips was estimated for each fungal species by comparing actual and randomly simulated distributions. In total, the three seedlings were colonized by 40 ECM fungal species. The composition of colonizing fungal species was quite different among the seedlings. Twelve of the 15 major ECM fungal species clustered significantly within a few centimeters. Some clusters overlapped or intermingled, while others were unique. Areas with high fungal species diversity were also identified in the root system. In this report, the mechanisms underlying generation of these ECM root tip clusters in the root system are discussed.

  6. Fine-Scale Distribution and Spatial Variability of Benthic Invertebrate Larvae in an Open Coastal Embayment in Nova Scotia, Canada

    PubMed Central

    Daigle, Rémi M.; Metaxas, Anna; deYoung, Brad

    2014-01-01

    This study quantified the fine- scale (0.5 km) of variability in the horizontal distributions of benthic invertebrate larvae and related this variability to that in physical and biological variables, such as density, temperature, salinity, fluorescence and current velocity. Larvae were sampled in contiguous 500-m transects along two perpendicular 10-km transects with a 200-µm plankton ring net (0.75-m diameter) in St. George’s Bay, Nova Scotia, Canada, in Aug 2009. Temperature, conductivity, pressure and fluorescence were measured with a CTD cast at each station, and currents were measured with an Acoustic Doppler Current Profiler moored at the intersection of the 2 transects. Gastropod, bivalve and, to a lesser extent, bryozoan larvae had very similar spatial distributions, but the distribution of decapod larvae had a different pattern. These findings suggest that taxonomic groups with functionally similar larvae have similar dispersive properties such as distribution and spatial variability, while the opposite is true for groups with functionally dissimilar larvae. The spatial variability in larval distributions was anisotropic and matched the temporal/spatial variability in the current velocity. We postulate that in a system with no strong oceanographic features, the scale of spatially coherent physical forcing (e.g. tidal periodicity) can regulate the formation or maintenance of larval patches; however, swimming ability may modulate it. PMID:25153075

  7. Fine-scale distribution of zooplankton is linked to phytoplankton species composition and abundance in a North Norwegian fjord system

    NASA Astrophysics Data System (ADS)

    Norrbin, F.; Priou, P. D.; Varela, A. P.

    2016-02-01

    We studied the influence of dense layers of phytoplankton and aggregates on shaping the vertical distribution of zooplankton in a North Norwegian fjord using a Video Plankton Recorder (VPR). This instrument provided fine-scale vertical distribution (cm-m scale) of planktonic organisms as well as aggregates of marine snow in relation to environmental conditions. At the height - later stage of the spring phytoplankton bloom in May, the outer part of the fjord was dominated by Phaeocystis pouchetii, while diatoms (Chaetoceros spp.) were dominating in the innermost basin. Small copepods species like Pseudocalanus spp., Microsetella norvegica, and Oithona spp. prevailed over larger copepod species in the inner part of the fjord whereas the outer part was dominated by large copepods like Calanus finmarchicus. While the zooplankton where spread out over the water column during the early stage of the bloom, in May they were linked to the phytoplankton vertical distribution and in the winter situation they were found in deeper waters. Herbivorous zooplankton species were affected by phytoplankton species composition; C. finmarchicus and Pseudocalanus spp. avoided the dense layer of P. pouchetii while herbivorous zooplankton matched the distribution of the diatom-dominated bloom. Small, omnivorous copepod species like Microsetella sp., Oithona sp. and Pseudocalanus sp. were often associated with dense layers of snow aggregates. This distribution may provide a shelter from predators as well as a food source. Natural or anthropogenic-induced changes in phytoplankton composition and aggregate distribution may thus influence food-web interactions.

  8. Kinship, inbreeding and fine-scale spatial structure influence gut microbiota in a hindgut-fermenting tortoise.

    PubMed

    Yuan, Michael L; Dean, Samantha H; Longo, Ana V; Rothermel, Betsie B; Tuberville, Tracey D; Zamudio, Kelly R

    2015-05-01

    Herbivorous vertebrates rely on complex communities of mutualistic gut bacteria to facilitate the digestion of celluloses and hemicelluloses. Gut microbes are often convergent based on diet and gut morphology across a phylogenetically diverse group of mammals. However, little is known about microbial communities of herbivorous hindgut-fermenting reptiles. Here, we investigate how factors at the individual level might constrain the composition of gut microbes in an obligate herbivorous reptile. Using multiplexed 16S rRNA gene sequencing, we characterized the faecal microbial community of a population of gopher tortoises (Gopherus polyphemus) and examined how age, genetic diversity, spatial structure and kinship influence differences among individuals. We recovered phylotypes associated with known cellulolytic function, including candidate phylum Termite Group 3, suggesting their importance for gopher tortoise digestion. Although host genetic structure did not explain variation in microbial composition and community structure, we found that fine-scale spatial structure, inbreeding, degree of relatedness and possibly ontogeny shaped patterns of diversity in faecal microbiomes of gopher tortoises. Our findings corroborate widespread convergence of faecal-associated microbes based on gut morphology and diet and demonstrate the role of spatial and demographic structure in driving differentiation of gut microbiota in natural populations.

  9. Activity patterns and fine-scale resource partitioning in the gregarious Kihansi spray toad Nectophrynoides asperginis in captivity.

    PubMed

    Rija, Alfan A; Goboro, Ezekiel M; Mwamende, Kuruthumu A; Said, Abubakari; Kohi, Edward M; Hassan, Shombe N

    2014-01-01

    Understanding the behavior of species threatened with extinction is important for conservation planning and for solving problems facing species in captivity and the wild. We examined diurnal activity budgets and habitat use of the extinct in the wild Kihansi spray toad to provide insights into ongoing conservation initiatives for this species. Observations on eight target behaviors were made each morning and evening for 14 days, in two subpopulations at Kihansi and University of Dar es Salaam captive breeding centers. There were significantly more bouts of resting than calling, amplexing, hunting, walking, climbing, or feeding. There was no difference in mean time spent in each activity between the two subpopulations. The use of habitat was variable between age classes, subpopulations and sampling time. Young toads spent significantly more time resting at the top of vegetation and on walls while adults rested more on logs. Further, adults foraged more on the walls and vegetation in the morning and on the ground in the evening. Contrastingly, young toads foraged more on the ground in the morning and switched to elevated patches during evening. The similarity of the toads' behavior suggests that important biological traits are still maintained in captivity and retained across toad generations. Furthermore, temporal and spatial variations in the use of habitat structures between age groups suggest fine-scale resource partitioning to reduce competition in this gregarious species. These results highlight the importance of maintaining diverse habitat structures in captivity and are useful for planning species reintroduction and future restocking programs. © 2014 Wiley Periodicals, Inc.

  10. Fine scale patterns of genetic partitioning in the rediscovered African crocodile, Crocodylus suchus (Saint-Hilaire 1807)

    PubMed Central

    Shirley, Matthew H.; Hekkala, Evon R.

    2016-01-01

    Landscape heterogeneity, phylogenetic history, and stochasticity all influence patterns of geneflow and connectivity in wild vertebrates. Fine-scale patterns of genetic partitioning may be particularly important for the sustainable management of widespread species in trade, such as crocodiles. We examined genetic variation within the rediscovered African crocodile, Crocodylus suchus, across its distribution in West and Central Africa. We genotyped 109 individuals at nine microsatellite loci from 16 sampling localities and used three Bayesian clustering techniques and an analysis of contemporary gene flow to identify population structure across the landscape. We identified up to eight genetic clusters that largely correspond to populations isolated in coastal wetland systems and across large distances. Crocodile population clusters from the interior were readily distinguished from coastal areas, which were further subdivided by distance and drainage basin. Migration analyses indicated contemporary migration only between closely positioned coastal populations. These findings indicate high levels of population structure throughout the range of C. suchus and we use our results to suggest a role for molecular tools in identifying crocodile conservation units for this species. Further research, including additional sampling throughout the Congo and Niger drainages, would clarify both the landscape connectivity and management of this species. PMID:27114867

  11. Fine scale patterns of genetic partitioning in the rediscovered African crocodile, Crocodylus suchus (Saint-Hilaire 1807).

    PubMed

    Cunningham, Seth W; Shirley, Matthew H; Hekkala, Evon R

    2016-01-01

    Landscape heterogeneity, phylogenetic history, and stochasticity all influence patterns of geneflow and connectivity in wild vertebrates. Fine-scale patterns of genetic partitioning may be particularly important for the sustainable management of widespread species in trade, such as crocodiles. We examined genetic variation within the rediscovered African crocodile, Crocodylus suchus, across its distribution in West and Central Africa. We genotyped 109 individuals at nine microsatellite loci from 16 sampling localities and used three Bayesian clustering techniques and an analysis of contemporary gene flow to identify population structure across the landscape. We identified up to eight genetic clusters that largely correspond to populations isolated in coastal wetland systems and across large distances. Crocodile population clusters from the interior were readily distinguished from coastal areas, which were further subdivided by distance and drainage basin. Migration analyses indicated contemporary migration only between closely positioned coastal populations. These findings indicate high levels of population structure throughout the range of C. suchus and we use our results to suggest a role for molecular tools in identifying crocodile conservation units for this species. Further research, including additional sampling throughout the Congo and Niger drainages, would clarify both the landscape connectivity and management of this species.

  12. RAD sequencing resolves fine-scale population structure in a benthic invertebrate: implications for understanding phenotypic plasticity

    PubMed Central

    Weigand, Hannah; Weiss, Martina; Fawcett, Katie; Lehman, Katrin; Clark, M. S.; Leese, Florian; McMinn, Carrie; Moore, Heather; Hoffman, Joseph I.

    2017-01-01

    The field of molecular ecology is transitioning from the use of small panels of classical genetic markers such as microsatellites to much larger panels of single nucleotide polymorphisms (SNPs) generated by approaches like RAD sequencing. However, few empirical studies have directly compared the ability of these methods to resolve population structure. This could have implications for understanding phenotypic plasticity, as many previous studies of natural populations may have lacked the power to detect genetic differences, especially over micro-geographic scales. We therefore compared the ability of microsatellites and RAD sequencing to resolve fine-scale population structure in a commercially important benthic invertebrate by genotyping great scallops (Pecten maximus) from nine populations around Northern Ireland at 13 microsatellites and 10 539 SNPs. The shells were then subjected to morphometric and colour analysis in order to compare patterns of phenotypic and genetic variation. We found that RAD sequencing was superior at resolving population structure, yielding higher Fst values and support for two distinct genetic clusters, whereas only one cluster could be detected in a Bayesian analysis of the microsatellite dataset. Furthermore, appreciable phenotypic variation was observed in size-independent shell shape and coloration, including among localities that could not be distinguished from one another genetically, providing support for the notion that these traits are phenotypically plastic. Taken together, our results suggest that RAD sequencing is a powerful approach for studying population structure and phenotypic plasticity in natural populations. PMID:28386419

  13. Oscillatory flow braking: inner magnetosphere observations

    NASA Astrophysics Data System (ADS)

    Panov, E. V.; Nakamura, R.; Baumjohann, W.; Angelopoulos, V.

    2013-12-01

    We search for damped oscillatory flow braking events observed by THEMIS/ARTEMIS in the near-Earth plasma sheet when their counterpart in the inner magnetosphere was observed. By comparing the particle and magnetic field data in the two locations we analyze the feedback of the inner magnetosphere to plasma sheet oscillatory flow braking. We discuss the possible role of the oscillatory flow events for plasma injection into the inner magnetosphere.

  14. A Positive Displacement Oscillatory Water Tunnel.

    DTIC Science & Technology

    1977-02-01

    v — - AD AO3S 593 NATIONAL BUREAU OF STANDARDS WASHINGTON 0 C MECHANICS DIV FIG 1’~/2A POSITIVE DISPLACEMENT OSCILLATORY WATER TUNNEL. (U) FEB 77 K...motion (maximum half stroke) s displacement of pistons from zero level Sr displacement of free surface in reservoirs from zero level T period of...A POSITIVE DISPLACEMENT OSCILLATORY WATER TUNNEL by - - Karl E. B. Lofquist I. INTRODUCTION This report describes a general purpose oscillatory

  15. Heteroclinic contours in oscillatory ensembles.

    PubMed

    Komarov, M A; Osipov, G V; Zhou, C S

    2013-02-01

    In this work, we study the onset of sequential activity in ensembles of neuronlike oscillators with inhibitorylike coupling between them. The winnerless competition (WLC) principle is a dynamical concept underlying sequential activity generation. According to the WLC principle, stable heteroclinic sequences in the phase space of a network model represent sequential metastable dynamics. We show that stable heteroclinic sequences and stable heteroclinic channels, connecting saddle limit cycles, can appear in oscillatory models of neural activity. We find the key bifurcations which lead to the occurrence of sequential activity as well as heteroclinic sequences and channels.

  16. Fluctuations of Prestimulus Oscillatory Power Predict Subjective Perception of Tactile Simultaneity

    PubMed Central

    Halacz, Johanna; van Dijk, Hanneke; Kahlbrock, Nina; Schnitzler, Alfons

    2012-01-01

    Oscillatory activity is modulated by sensory stimulation but can also fluctuate in the absence of sensory input. Recent studies have demonstrated that such fluctuations of oscillatory activity can have substantial influence on the perception of subsequent stimuli. In the present study, we employed a simultaneity task in the somatosensory domain to study the role of prestimulus oscillatory activity on the temporal perception of 2 events. Subjects received electrical stimulations of the left and right index finger with varying stimulus onset asynchronies (SOAs) and reported their subjective perception of simultaneity, while brain activity was recorded with magnetoencephalography. With intermediate SOAs (30 and 45 ms), subjects frequently misperceived the stimulation as simultaneously. We compared neuronal oscillatory power in these conditions and found that power in the high beta band (∼20 to 40 Hz) in primary and secondary somatosensory cortex prior to the electrical stimulation predicted subjects' reports of simultaneity. Additionally, prestimulus alpha-band power influenced perception in the condition SOA 45 ms. Our results indicate that fluctuations of ongoing oscillatory activity in the beta and alpha bands shape subjective perception of physically identical stimulation. PMID:22114082

  17. Fluctuations of prestimulus oscillatory power predict subjective perception of tactile simultaneity.

    PubMed

    Lange, Joachim; Halacz, Johanna; van Dijk, Hanneke; Kahlbrock, Nina; Schnitzler, Alfons

    2012-11-01

    Oscillatory activity is modulated by sensory stimulation but can also fluctuate in the absence of sensory input. Recent studies have demonstrated that such fluctuations of oscillatory activity can have substantial influence on the perception of subsequent stimuli. In the present study, we employed a simultaneity task in the somatosensory domain to study the role of prestimulus oscillatory activity on the temporal perception of 2 events. Subjects received electrical stimulations of the left and right index finger with varying stimulus onset asynchronies (SOAs) and reported their subjective perception of simultaneity, while brain activity was recorded with magnetoencephalography. With intermediate SOAs (30 and 45 ms), subjects frequently misperceived the stimulation as simultaneously. We compared neuronal oscillatory power in these conditions and found that power in the high beta band (∼20 to 40 Hz) in primary and secondary somatosensory cortex prior to the electrical stimulation predicted subjects' reports of simultaneity. Additionally, prestimulus alpha-band power influenced perception in the condition SOA 45 ms. Our results indicate that fluctuations of ongoing oscillatory activity in the beta and alpha bands shape subjective perception of physically identical stimulation.

  18. DISTINCTIVE FINE-SCALE MORPHOLOGY OF GAS-RICH SITES ON THE CASCADIA MARGIN NEAR BULLSEYE VENT

    NASA Astrophysics Data System (ADS)

    Thomas, H.; Paull, C. K.; Caress, D. W.; Ussler, W.; Lundsten, E.; Riedel, M.

    2009-12-01

    High-resolution multibeam bathymetry (vertical precision of 0.15 m and horizontal resolution of 1.0 m) and 2-10 kHz chirp seismic reflection profiles were recently collected over a small section of the Cascadia continental margin off British Columbia. The surveys were conducted using an autonomous underwater vehicle (AUV) and reveal in unprecedented detail fine-scale morphology and shallow seafloor structure. An inertial navigation system aided by a Doppler velocity log allows the AUV to fly pre-programmed grids with 150 m line spacing at 3 knots while maintaining an altitude of 50 m above the seafloor. The data were collected on three 17-hour-long dives in 1170 to 1410 m water depths focused on a 9.5 km long and ~3 km wide area on both sides of a node on the scientific research cable deployed by the Canadian Neptune Project. These surveys also cover the near seafloor associated with gas hydrate research boreholes at ODP Site 889/890, and IODP Site 1328 (Bullseye Vent). While the fine-scale texture of the seafloor is generally smooth throughout the surveyed area, there are notable exceptions. The crests of the tectonic ridges show a very distinctive hummocky topography. This topography is characterized by a highly irregular surface formed by small sometimes circular ~0.5 m deep pits, local highs and lows separated by ~0.5 m high ledges that could be formed by irregularly eroded bedding surfaces. Similar shapes also occur at larger scales including crater-like features that are up to 80 m across, raised rims, and more than 5 m deep central ‘crater’. A similar texture has been observed in other AUV surveys associated with methane-derived carbonate bearing sites known to overlie near seafloor gas hydrate deposits on Hydrate Ridge. Prior to this survey Bullseye Vent was believed to be associated with a roughly circular subtle topographic high (~2 m high) with a ~350 m diameter. The AUV data reveal Bullseye Vent to be a depression (~300 m long, ~70 m wide, up to 7 m

  19. Combined Use of GPS and Accelerometry Reveals Fine Scale Three-Dimensional Foraging Behaviour in the Short-Tailed Shearwater

    PubMed Central

    Berlincourt, Maud; Angel, Lauren P.; Arnould, John P. Y.

    2015-01-01

    Determining the foraging behaviour of free-ranging marine animals is fundamental for assessing their habitat use and how they may respond to changes in the environment. However, despite recent advances in bio-logging technology, collecting information on both at-sea movement patterns and activity budgets still remains difficult in small pelagic seabird species due to the constraints of instrument size. The short-tailed shearwater, the most abundant seabird species in Australia (ca 23 million individuals), is a highly pelagic procellariiform. Despite its ecological importance to the region, almost nothing is known about its at-sea behaviour, in particular, its foraging activity. Using a combination of GPS and tri-axial accelerometer data-loggers, the fine scale three-dimensional foraging behaviour of 10 breeding individuals from two colonies was investigated. Five at-sea behaviours were identified: (1) resting on water, (2) flapping flight, (3) gliding flight, (4) foraging (i.e., surface foraging and diving events), and (5) taking-off. There were substantial intra- and inter- individual variations in activity patterns, with individuals spending on average 45.8% (range: 17.1–70.0%) of time at sea resting on water and 18.2% (range: 2.3–49.6%) foraging. Individuals made 76.4 ± 65.3 dives (range: 8–237) per foraging trip (mean duration 9.0 ± 1.9 s), with dives also recorded during night-time. With the continued miniaturisation of recording devices, the use of combined data-loggers could provide us with further insights into the foraging behaviour of small procellariiforms, helping to better understand interactions with their prey. PMID:26439491

  20. Fine-Scale Cartography of Human Impacts along French Mediterranean Coasts: A Relevant Map for the Management of Marine Ecosystems.

    PubMed

    Holon, Florian; Mouquet, Nicolas; Boissery, Pierre; Bouchoucha, Marc; Delaruelle, Gwenaelle; Tribot, Anne-Sophie; Deter, Julie

    2015-01-01

    Ecosystem services provided by oceans and seas support most human needs but are threatened by human activities. Despite existing maps illustrating human impacts on marine ecosystems, information remains either large-scale but rough and insufficient for stakeholders (1 km² grid, lack of data along the coast) or fine-scale but fragmentary and heterogeneous in methodology. The objectives of this study are to map and quantify the main pressures exerted on near-coast marine ecosystems, at a large spatial scale though in fine and relevant resolution for managers (one pixel = 20 x 20 m). It focuses on the French Mediterranean coast (1,700 km of coastline including Corsica) at a depth of 0 to 80 m. After completing and homogenizing data presently available under GIS on the bathymetry and anthropogenic pressures but also on the seabed nature and ecosystem vulnerability, we provide a fine modeling of the extent and impacts of 10 anthropogenic pressures on marine habitats. The considered pressures are man-made coastline, boat anchoring, aquaculture, urban effluents, industrial effluents, urbanization, agriculture, coastline erosion, coastal population and fishing. A 1:10 000 continuous habitat map is provided considering 11 habitat classes. The marine bottom is mostly covered by three habitats: infralittoral soft bottom, Posidonia oceanica meadows and circalittoral soft bottom. Around two thirds of the bottoms are found within medium and medium high cumulative impact categories. Seagrass meadows are the most impacted habitats. The most important pressures (in area and intensity) are urbanization, coastal population, coastal erosion and man-made coastline. We also identified areas in need of a special management interest. This work should contribute to prioritize environmental needs, as well as enhance the development of indicators for the assessment of the ecological status of coastal systems. It could also help better apply and coordinate management measures at a relevant

  1. Fine-Scale Community Structure Analysis of ANME in Nyegga Sediments with High and Low Methane Flux

    PubMed Central

    Roalkvam, Irene; Dahle, Håkon; Chen, Yifeng; Jørgensen, Steffen Leth; Haflidason, Haflidi; Steen, Ida Helene

    2012-01-01

    To obtain knowledge on how regional variations in methane seepage rates influence the stratification, abundance, and diversity of anaerobic methanotrophs (ANME), we analyzed the vertical microbial stratification in a gravity core from a methane micro-seeping area at Nyegga by using 454-pyrosequencing of 16S rRNA gene tagged amplicons and quantitative PCR. These data were compared with previously obtained data from the more active G11 pockmark, characterized by higher methane flux. A down core stratification and high relative abundance of ANME were observed in both cores, with transition from an ANME-2a/b dominated community in low-sulfide and low methane horizons to ANME-1 dominance in horizons near the sulfate-methane transition zone. The stratification was over a wider spatial region and at greater depth in the core with lower methane flux, and the total 16S rRNA copy numbers were two orders of magnitude lower than in the sediments at G11 pockmark. A fine-scale view into the ANME communities at each location was achieved through operational taxonomical units (OTU) clustering of ANME-affiliated sequences. The majority of ANME-1 sequences from both sampling sites clustered within one OTU, while ANME-2a/b sequences were represented in unique OTUs. We suggest that free-living ANME-1 is the most abundant taxon in Nyegga cold seeps, and also the main consumer of methane. The observation of specific ANME-2a/b OTUs at each location could reflect that organisms within this clade are adapted to different geochemical settings, perhaps due to differences in methane affinity. Given that the ANME-2a/b population could be sustained in less active seepage areas, this subgroup could be potential seed populations in newly developed methane-enriched environments. PMID:22715336

  2. High genetic diversity and fine-scale spatial structure in the marine flagellate Oxyrrhis marina (Dinophyceae) uncovered by microsatellite loci.

    PubMed

    Lowe, Chris D; Montagnes, David J S; Martin, Laura E; Watts, Phillip C

    2010-12-23

    Free-living marine protists are often assumed to be broadly distributed and genetically homogeneous on large spatial scales. However, an increasing application of highly polymorphic genetic markers (e.g., microsatellites) has provided evidence for high genetic diversity and population structuring on small spatial scales in many free-living protists. Here we characterise a panel of new microsatellite markers for the common marine flagellate Oxyrrhis marina. Nine microsatellite loci were used to assess genotypic diversity at two spatial scales by genotyping 200 isolates of O. marina from 6 broad geographic regions around Great Britain and Ireland; in one region, a single 2 km shore line was sampled intensively to assess fine-scale genetic diversity. Microsatellite loci resolved between 1-6 and 7-23 distinct alleles per region in the least and most variable loci respectively, with corresponding variation in expected heterozygosities (H(e)) of 0.00-0.30 and 0.81-0.93. Across the dataset, genotypic diversity was high with 183 genotypes detected from 200 isolates. Bayesian analysis of population structure supported two model populations. One population was distributed across all sampled regions; the other was confined to the intensively sampled shore, and thus two distinct populations co-occurred at this site. Whilst model-based analysis inferred a single UK-wide population, pairwise regional F(ST) values indicated weak to moderate population sub-division (0.01-0.12), but no clear correlation between spatial and genetic distance was evident. Data presented in this study highlight extensive genetic diversity for O. marina; however, it remains a substantial challenge to uncover the mechanisms that drive genetic diversity in free-living microorganisms.

  3. Fine-scale Clonal Structure and Diversity within Patches of a Clone-forming Dioecious Shrub, Ilex leucoclada (Aquifoliaceae)

    PubMed Central

    TORIMARU, TAKESHI; TOMARU, NOBUHIRO

    2004-01-01

    • Background and Aims The mode of reproduction (sexual vs. asexual) is likely to have important effects on genetic variation and its spatial distribution within plant populations. An investigation was undertaken of fine-scale clonal structure and diversity within patches of Ilex leucoclada (a clone-forming dioecious shrub). • Methods Six patches were selected in a 1-ha plot previously established in an old-growth beech forest. Two of the selected patches were composed predominantly of stems with male flowers (male patch), and two contained stems with predominantly female flowers (female patch). The remaining two patches contained stems with male flowers and stems with female flowers in more or less equal proportions (mixed patch). Different genets were distinguished using random amplified polymorphic DNA (RAPD) markers. • Key Results One hundred and fifty-six genets with different RAPD phenotypes were identified among 1928 stems from the six patches. Among the six patches, the male patches had the lowest clonal diversity, and the mixed patches had the highest. Distribution maps of the genets showed that they extended downhill, reflecting natural layering that occurred when stems were pressed to the ground by heavy snow. In every patch, there were a few large genets with many stems and many small genets with a few stems. • Conclusion The differences in clonal diversity among patches may be due to differences in seedling recruitment frequencies. The skewed distribution of genet size (defined as the number of stems per genet) within patches may be due to differences in the timing of germination, or age (with early-establishing genets having clear advantages for acquiring resources) and/or intraspecific competition. PMID:15546930

  4. Implications of Fine-Scale Geochemical Depth Trends in the Active Layer of a Continuous Permafrost Landscape near Barrow, Alaska

    NASA Astrophysics Data System (ADS)

    Newman, B. D.; Heikoop, J. M.; Throckmorton, H.; Wilson, C. J.; Wullschleger, S. D.

    2014-12-01

    As part of the US DOE, Office of Science, Next Generation Ecosystem Experiment-Arctic project, we have been using environmental tracers (naturally occurring stable isotopes and geochemical species) to understand hydrological and geochemical processes within polygonal ground in a continuous permafrost area in the Arctic coastal plain. The study site is characterized by a thin zone of active layer development (typically <50 cm). This condition makes it difficult to understand development of geochemical gradients between the near surface and the frost line because traditional sampling using pumping causes mixing which can obscure depth gradients. We have applied a passive approach by using a series of diffusion cells that are installed at different depths within the active zone. The cells are filled with deionized water and over time, they equilibrate with the adjacent active layer water chemistry (ions diffuse into the cell, but the water in the cell does not exchange). Using this approach we have collected a series of fine resolution depth profiles within saturated zones in the active layer. Results over the last three years often show well-developed and sometimes substantial geochemical gradients for multiple analytes. Such gradients imply minimal vertical mixing within the active zone. Reductions in permeability with depth and lack of strong hydrological gradients likely limit vertical mixing. We also noted that the strength of the depth gradients varies across the landscape reflecting differences related to microtopography and drainage conditions. These results suggest that there are likely to be substantial fine-scale depth variations in biogeochemical processes such as methane and carbon dioxide production. Hydrological models should also reflect limited mixing with depth.

  5. Fine-Scale Genetic Structure of Monilinia fructicola During Brown Rot Epidemics Within Individual Peach Tree Canopies.

    PubMed

    Everhart, S E; Scherm, H

    2015-04-01

    The purpose of this study was to determine the fine-scale genetic structure of populations of the brown rot pathogen Monilinia fructicola within individual peach tree canopies to better understand within-tree plant pathogen diversity and to complement previous work on spatiotemporal development of brown rot disease at the canopy level. Across 3 years in a total of six trees, we monitored disease development, collected isolates from every M. fructicola symptom during the course of the season, and created high-resolution three-dimensional maps of all symptom and isolate locations within individual canopies using an electromagnetic digitizer. Each canopy population (65 to 173 isolates per tree) was characterized using a set of 13 microsatellite markers and analyzed for evidence of spatial genetic autocorrelation among isolates during the epidemic phase of the disease. Results showed high genetic diversity (average uh=0.529) and high genotypic diversity (average D=0.928) within canopies. The percentage of unique multilocus genotypes within trees was greater for blossom blight isolates (78.2%) than for fruit rot isolates (51.3%), indicating a greater contribution of clonal reproduction during the preharvest epidemic. For fruit rot isolates, between 54.2 and 81.7% of isolates were contained in one to four dominant clonal genotypes per tree having at least 10 members. All six fruit rot populations showed positive and significant spatial genetic autocorrelation for distance classes between 0.37 and 1.48 m. Despite high levels of within-tree pathogen diversity, the contribution of locally available inoculum combined with short-distance dispersal is likely the main factor generating clonal population foci and associated spatial genetic clustering within trees.

  6. Disturbances can control fine-scale pedodiversity in old-growth forest: is the soil evolution theory disturbed as well?

    NASA Astrophysics Data System (ADS)

    Šamonil, P.; Vašíčková, I.; Daněk, P.; Janík, D.; Adam, D.

    2014-04-01

    Biota-soil interaction in natural ecosystems is an area of considerable research. Our hypothesis is that individual trees play a significant role through biomechanical and biochemical disturbances in soil formation in temperate forest resulting in complex spatial pattern of disturbance regimes and a close relationship between disturbance histories and soil units. In Žofínský Prales (Czech Republic) - the fourth oldest, continuously protected reserve in Europe and the only SIGEO site in continental Europe - in time and space we compared extensive dendrochronological, soil and pit-mound microtopography data on an area of 42.01 ha collected in 2008-2012. The datasets differ in terms of information complexity and length of memory. Tree cores contain complex information about disturbance history of the past 350 years, footprints of the specific tree uprooting disturbance can persist 1700 years, and soils representing extensive composite phenotype have been developing for at least the entire postglacial period (10 500 years). On average, 6.18-13.41% of the canopy was disturbed on individual soil units per decade. Even though the "backbone" of key events in the development of the forest ecosystem remained the same (e.g. the 1870s, 1880s and 1980s), the internal structure of disturbance history often differed among soil units; the most exceptional were Gleysols and Histosols, where important feedback from soil to trees was expected. However characteristics of treethrow dynamics as well as frequencies of stronger releases in core series significantly differed also along a gradient of terrestrial soil weathering and leaching (Haplic Cambisols - Dystric Cambisols - Entic Podzols - Albic Podzols). Results suggest the existence of several disturbance regimes within the forest controlling fine-scale pedodiversity.

  7. Disturbances can control fine-scale pedodiversity in old-growth forests: is the soil evolution theory disturbed as well?

    NASA Astrophysics Data System (ADS)

    Šamonil, P.; Vašíčková, I.; Daněk, P.; Janík, D.; Adam, D.

    2014-10-01

    Biota-soil interactions in natural ecosystems are the subject of considerable research. Our hypothesis is that individual trees play a significant role through biomechanical and biochemical disturbances affecting soil formation in temperate forests, resulting in a complex spatial pattern of disturbance regimes and a close relationship between disturbance histories and soil units. In Žofínský Prales (Czech Republic) - the fourth oldest, continuously protected reserve in Europe and the first site of global research network SIGEO (Smithsonian Institution Global Earth Observatories) in continental Europe - we compared extensive dendrochronological, soil and pit-mound microtopography data both temporally and spatially from an area of anthropogenically unaffected 42 ha collected from 2008-2012. These data sets differ in terms of information complexity and length of memory: tree cores contain complex information about the disturbance history of the past 350 years, footprints of disturbances from the uprooting of a specific tree can persist 1700 years, and soils represent an extensive composite phenotype that has been developing for at least the entire postglacial period (10 500 years). On average, 6.18-13.41% of the canopy on individual soil units was disturbed per decade. Even though the "backbone" of key events in the development of the forest ecosystem remained the same (e.g. the 1870s, 1880s and 1980s), the internal structure of disturbance history often differed among soil units; the most exceptional were Gleysols and Histosols, where important feedback from soil to trees was expected. However, the characteristics of treethrow dynamics as well as the frequencies of stronger releases in core series also significantly differed along a gradient of terrestrial soil weathering and leaching (Haplic Cambisols - Dystric Cambisols - Entic Podzols - Albic Podzols). These results suggest the existence of several disturbance regimes within the forest, controlling fine-scale

  8. Pollen-mediated gene flow and fine-scale spatial genetic structure in Olea europaea subsp. europaea var. sylvestris.

    PubMed

    Beghè, D; Piotti, A; Satovic, Z; de la Rosa, R; Belaj, A

    2017-03-01

    Wild olive ( Olea europaea subsp. europaea var. sylvestris ) is important from an economic and ecological point of view. The effects of anthropogenic activities may lead to the genetic erosion of its genetic patrimony, which has high value for breeding programmes. In particular, the consequences of the introgression from cultivated stands are strongly dependent on the extent of gene flow and therefore this work aims at quantitatively describing contemporary gene flow patterns in wild olive natural populations. The studied wild population is located in an undisturbed forest, in southern Spain, considered one of the few extant hotspots of true oleaster diversity. A total of 225 potential father trees and seeds issued from five mother trees were genotyped by eight microsatellite markers. Levels of contemporary pollen flow, in terms of both pollen immigration rates and within-population dynamics, were measured through paternity analyses. Moreover, the extent of fine-scale spatial genetic structure (SGS) was studied to assess the relative importance of seed and pollen dispersal in shaping the spatial distribution of genetic variation. The results showed that the population under study is characterized by a high genetic diversity, a relatively high pollen immigration rate (0·57), an average within-population pollen dispersal of about 107 m and weak but significant SGS up to 40 m. The population is a mosaic of several intermingled genetic clusters that is likely to be generated by spatially restricted seed dispersal. Moreover, wild oleasters were found to be self-incompatible and preferential mating between some genotypes was revealed. Knowledge of the within-population genetic structure and gene flow dynamics will lead to identifying possible strategies aimed at limiting the effect of anthropogenic activities and improving breeding programmes for the conservation of olive tree forest genetic resources.

  9. High Genetic Diversity and Fine-Scale Spatial Structure in the Marine Flagellate Oxyrrhis marina (Dinophyceae) Uncovered by Microsatellite Loci

    PubMed Central

    Lowe, Chris D.; Montagnes, David J. S.; Martin, Laura E.; Watts, Phillip C.

    2010-01-01

    Free-living marine protists are often assumed to be broadly distributed and genetically homogeneous on large spatial scales. However, an increasing application of highly polymorphic genetic markers (e.g., microsatellites) has provided evidence for high genetic diversity and population structuring on small spatial scales in many free-living protists. Here we characterise a panel of new microsatellite markers for the common marine flagellate Oxyrrhis marina. Nine microsatellite loci were used to assess genotypic diversity at two spatial scales by genotyping 200 isolates of O. marina from 6 broad geographic regions around Great Britain and Ireland; in one region, a single 2 km shore line was sampled intensively to assess fine-scale genetic diversity. Microsatellite loci resolved between 1–6 and 7–23 distinct alleles per region in the least and most variable loci respectively, with corresponding variation in expected heterozygosities (He) of 0.00–0.30 and 0.81–0.93. Across the dataset, genotypic diversity was high with 183 genotypes detected from 200 isolates. Bayesian analysis of population structure supported two model populations. One population was distributed across all sampled regions; the other was confined to the intensively sampled shore, and thus two distinct populations co-occurred at this site. Whilst model-based analysis inferred a single UK-wide population, pairwise regional FST values indicated weak to moderate population sub-division (0.01–0.12), but no clear correlation between spatial and genetic distance was evident. Data presented in this study highlight extensive genetic diversity for O. marina; however, it remains a substantial challenge to uncover the mechanisms that drive genetic diversity in free-living microorganisms. PMID:21203414

  10. Fine scale habitat use by age-1 stocked muskellunge and wild northern pike in an upper St. Lawrence River bay

    USGS Publications Warehouse

    Farrell, John M.; Kapuscinski, Kevin L.; Underwood, Harold

    2014-01-01

    Radio telemetry of stocked muskellunge (n = 6) and wild northern pike (n = 6) was used to track late summer and fall movements from a common release point in a known shared nursery bay to test the hypothesis that age-1 northern pike and stocked muskellunge segregate and have different habitat affinities. Water depth, temperature, substrate and aquatic vegetation variables were estimated for each muskellunge (n = 103) and northern pike (n = 131) position and nested ANOVA comparisons by species indicated differences in habitat use. Muskellunge exhibited a greater displacement from the release point and used habitat in shallower water depths (mean = 0.85 m, SE = 0.10) than northern pike (mean = 1.45 m, SE = 0.08). Both principal components analysis (PCA) and principal components ordination (PCO) were used to interpret underlying gradients relative to fish positions in two-dimensional space. Our analysis indicated that a separation of age-1 northern pike and muskellunge occurred 7 d post-release. This first principal component explained 48% of the variation in habitat use. Northern pike locations were associated with deeper habitats that generally had softer silt substrates and dense submersed vegetation. Muskellunge locations post-acclimation showed greater association with shallower habitats containing firmer sandy and clay substrates and emergent vegetation. The observed differences in habitat use suggest that fine-scale ecological separation occurred between these stocked muskellunge and wild northern pike, but small sample sizes and potential for individual variation limit extension of these conclusions. Further research is needed to determine if these patterns exist between larger samples of fishes over a greater range of habitats.

  11. Habitat selection during ungulate dispersal and exploratory movement at broad and fine scale with implications for conservation management.

    PubMed

    Killeen, Joshua; Thurfjell, Henrik; Ciuti, Simone; Paton, Dale; Musiani, Marco; Boyce, Mark S

    2014-01-01

    Dispersal has a critical influence on demography and gene flow and as such maintaining connectivity between populations is an essential element of modern conservation. Advances in satellite radiotelemetry are providing new opportunities to document dispersal, which previously has been difficult to study. This type of data also can be used as an empirical basis for defining landscapes in terms of resistance surfaces, enabling habitat corridors to be identified. However, despite the scale-dependent nature of habitat selection few studies have investigated selection specifically during dispersal. Here we investigate habitat selection during and around dispersal periods as well as the influence of age and sex on dispersal for a large ungulate. Of 158 elk (Cervus elaphus) tracked using GPS radiotelemetry almost all dispersers were males, with individuals dispersing up to 98 km. The dispersal period was distinct, with higher movement rates than before or after dispersal. At fine scale elk avoided the most rugged terrain in all time periods, but to a greater extent during and after dispersal, which we showed using step selection functions. In contrast, habitat selection by resident elk was less affected by ruggedness and more by an attraction to areas of higher forage availability. At the broad scale, however, movement corridors of dispersers were characterized by higher forage availability and slightly lower ruggedness then expected using correlated random walks. In one of the first examples of its kind we document complete long-distance dispersal events by an ungulate in detail. We find dispersal to be distinct in terms of movement rate and also find evidence that habitat selection during dispersal may differ from habitat selection in the home-range, with potential implications for the use of resistance surfaces to define conservation corridors.

  12. Characterization of turbulence from a fine-scale parameterization and microstructure measurements in the Mediterranean Sea during the BOUM experiment

    NASA Astrophysics Data System (ADS)

    Cuypers, Y.; Bouruet-Aubertot, P.; Marec, C.; Fuda, J.-L.

    2012-08-01

    One of the main purposes of the BOUM experiment was to find evidence of the possible impact of submesoscale dynamics on biogeochemical cycles. To this aim physical as well as biogeochemical data were collected along a zonal transect through the western and eastern basins of the Mediterranean Sea. Along this transect 3-day fixed point stations were performed within anticyclonic eddies during which microstructure measurements of the temperature gradient were collected over the top 100 m of the water column. We focus here on the characterization of turbulent mixing. The analysis of microstructure measurements revealed a high level of turbulent kinetic energy (TKE) dissipation rate in the seasonal pycnocline and a moderate level below with mean values of the order of 10-6 W kg-1 and 10-8 W kg-1, respectively. The Gregg Henyey (Gregg, 1989) fine-scale parameterization of TKE dissipation rate produced by internal wave breaking, and adapted here following Polzin et al. (1995) to take into account the strain to shear ratio, was first compared to these direct measurements with favorable results. The parameterization was then applied to the whole data set. Within the eddies, a significant increase of dissipation at the top and base of eddies associated with strong near-inertial waves is observed. Vertical turbulent diffusivity is increased both in these regions and in the weakly stratified eddy core. The stations collected along the East-West transect provide an overview of parameterized TKE dissipation rates and vertical turbulent diffusivity over a latitudinal section of the Mediterranean Sea. Strong TKE dissipation rates are found within the first 500 m and up to 1500 m above the bottom. Close to the bottom where the stratification is weak, the inferred vertical turbulent diffusivity can reach Kz≃10-3 m2 s-1 and may therefore have a strong impact on the upward diffusive transport of deep waters masses.

  13. Fine-Scale Community Structure Analysis of ANME in Nyegga Sediments with High and Low Methane Flux.

    PubMed

    Roalkvam, Irene; Dahle, Håkon; Chen, Yifeng; Jørgensen, Steffen Leth; Haflidason, Haflidi; Steen, Ida Helene

    2012-01-01

    To obtain knowledge on how regional variations in methane seepage rates influence the stratification, abundance, and diversity of anaerobic methanotrophs (ANME), we analyzed the vertical microbial stratification in a gravity core from a methane micro-seeping area at Nyegga by using 454-pyrosequencing of 16S rRNA gene tagged amplicons and quantitative PCR. These data were compared with previously obtained data from the more active G11 pockmark, characterized by higher methane flux. A down core stratification and high relative abundance of ANME were observed in both cores, with transition from an ANME-2a/b dominated community in low-sulfide and low methane horizons to ANME-1 dominance in horizons near the sulfate-methane transition zone. The stratification was over a wider spatial region and at greater depth in the core with lower methane flux, and the total 16S rRNA copy numbers were two orders of magnitude lower than in the sediments at G11 pockmark. A fine-scale view into the ANME communities at each location was achieved through operational taxonomical units (OTU) clustering of ANME-affiliated sequences. The majority of ANME-1 sequences from both sampling sites clustered within one OTU, while ANME-2a/b sequences were represented in unique OTUs. We suggest that free-living ANME-1 is the most abundant taxon in Nyegga cold seeps, and also the main consumer of methane. The observation of specific ANME-2a/b OTUs at each location could reflect that organisms within this clade are adapted to different geochemical settings, perhaps due to differences in methane affinity. Given that the ANME-2a/b population could be sustained in less active seepage areas, this subgroup could be potential seed populations in newly developed methane-enriched environments.

  14. Local topography shapes fine-scale spatial genetic structure in the Arkansas Valley evening primrose, Oenothera harringtonii (Onagraceae).

    PubMed

    Rhodes, Matthew K; Fant, Jeremie B; Skogen, Krissa A

    2014-01-01

    Identifying factors that shape the spatial distribution of genetic variation is crucial to understanding many population- and landscape-level processes. In this study, we explore fine-scale spatial genetic structure in Oenothera harringtonii (Onagraceae), an insect-pollinated, gravity-dispersed herb endemic to the grasslands of south-central and southeastern Colorado, USA. We genotyped 315 individuals with 11 microsatellite markers and utilized a combination of spatial autocorrelation analyses and landscape genetic models to relate life history traits and landscape features to dispersal processes. Spatial genetic structure was consistent with theoretical expectations of isolation by distance, but this pattern was weak (Sp = 0.00374). Anisotropic analyses indicated that spatial genetic structure was markedly directional, in this case consistent with increased dispersal along prominent slopes. Landscape genetic models subsequently confirmed that spatial genetic variation was significantly influenced by local topographic heterogeneity, specifically that geographic distance, elevation and aspect were important predictors of spatial genetic structure. Among these variables, geographic distance was ~68% more important than elevation in describing spatial genetic variation, and elevation was ~42% more important than aspect after removing the effect of geographic distance. From these results, we infer a mechanism of hydrochorous seed dispersal along major drainages aided by seasonal monsoon rains. Our findings suggest that landscape features may shape microevolutionary processes at much finer spatial scales than typically considered, and stress the importance of considering how particular dispersal vectors are influenced by their environmental context. © The American Genetic Association 2014. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  15. Contrasting patterns of clonality and fine-scale genetic structure in two rare sedges with differing geographic distributions

    PubMed Central

    Binks, R M; Millar, M A; Byrne, M

    2015-01-01

    For plants with mixed reproductive capabilities, asexual reproduction is more frequent in rare species and is considered a strategy for persistence when sexual recruitment is limited. We investigate whether asexual reproduction contributes to the persistence of two co-occurring, rare sedges that both experience irregular seed set and if their differing geographic distributions have a role in the relative contribution of clonality. Genotypic richness was high (R=0.889±0.02) across the clustered populations of Lepidosperma sp. Mt Caudan and, where detected, clonal patches were small, both in ramet numbers (⩽3 ramets/genet) and physical size (1.3±0.1 m). In contrast, genotypic richness was lower in the isolated L. sp. Parker Range populations, albeit more variable (R=0.437±0.13), with genets as large as 17 ramets and up to 5.8 m in size. Aggregated clonal growth generated significant fine-scale genetic structure in both species but to a greater spatial extent and with additional genet-level structure in L. sp. Parker Range that is likely due to restricted seed dispersal. Despite both species being rare, asexual reproduction clearly has a more important role in the persistence of L. sp. Parker Range than L. sp. Mt Caudan. This is consistent with our prediction that limitations to sexual reproduction, via geographic isolation to effective gene exchange, can lead to greater contributions of asexual reproduction. These results demonstrate the role of population isolation in affecting the balance of alternate reproductive modes and the contextual nature of asexual reproduction in rare species. PMID:25873148

  16. Human Social Behavior and Demography Drive Patterns of Fine-Scale Dengue Transmission in Endemic Areas of Colombia.

    PubMed

    Padmanabha, Harish; Correa, Fabio; Rubio, Camilo; Baeza, Andres; Osorio, Salua; Mendez, Jairo; Jones, James Holland; Diuk-Wasser, Maria A

    2015-01-01

    Dengue is known to transmit between humans and A. aegypti mosquitoes living in neighboring houses. Although transmission is thought to be highly heterogeneous in both space and time, little is known about the patterns and drivers of transmission in groups of houses in endemic settings. We carried out surveys of PCR positivity in children residing in 2-block patches of highly endemic cities of Colombia. We found high levels of heterogeneity in PCR positivity, varying from less than 30% in 8 of the 10 patches to 56 and 96%, with the latter patch containing 22 children simultaneously PCR positive (PCR22) for DEN2. We then used an agent-based model to assess the likely eco-epidemiological context of this observation. Our model, simulating daily dengue dynamics over a 20 year period in a single two block patch, suggests that the observed heterogeneity most likely derived from variation in the density of susceptible people. Two aspects of human adaptive behavior were critical to determining this density: external social relationships favoring viral introduction (by susceptible residents or infectious visitors) and immigration of households from non-endemic areas. External social relationships generating frequent viral introduction constituted a particularly strong constraint on susceptible densities, thereby limiting the potential for explosive outbreaks and dampening the impact of heightened vectorial capacity. Dengue transmission can be highly explosive locally, even in neighborhoods with significant immunity in the human population. Variation among neighborhoods in the density of local social networks and rural-to-urban migration is likely to produce significant fine-scale heterogeneity in dengue dynamics, constraining or amplifying the impacts of changes in mosquito populations and cross immunity between serotypes.

  17. Human Social Behavior and Demography Drive Patterns of Fine-Scale Dengue Transmission in Endemic Areas of Colombia

    PubMed Central

    Padmanabha, Harish; Correa, Fabio; Rubio, Camilo; Baeza, Andres; Osorio, Salua; Mendez, Jairo; Jones, James Holland; Diuk-Wasser, Maria A

    2015-01-01

    Dengue is known to transmit between humans and A. aegypti mosquitoes living in neighboring houses. Although transmission is thought to be highly heterogeneous in both space and time, little is known about the patterns and drivers of transmission in groups of houses in endemic settings. We carried out surveys of PCR positivity in children residing in 2-block patches of highly endemic cities of Colombia. We found high levels of heterogeneity in PCR positivity, varying from less than 30% in 8 of the 10 patches to 56 and 96%, with the latter patch containing 22 children simultaneously PCR positive (PCR22) for DEN2. We then used an agent-based model to assess the likely eco-epidemiological context of this observation. Our model, simulating daily dengue dynamics over a 20 year period in a single two block patch, suggests that the observed heterogeneity most likely derived from variation in the density of susceptible people. Two aspects of human adaptive behavior were critical to determining this density: external social relationships favoring viral introduction (by susceptible residents or infectious visitors) and immigration of households from non-endemic areas. External social relationships generating frequent viral introduction constituted a particularly strong constraint on susceptible densities, thereby limiting the potential for explosive outbreaks and dampening the impact of heightened vectorial capacity. Dengue transmission can be highly explosive locally, even in neighborhoods with significant immunity in the human population. Variation among neighborhoods in the density of local social networks and rural-to-urban migration is likely to produce significant fine-scale heterogeneity in dengue dynamics, constraining or amplifying the impacts of changes in mosquito populations and cross immunity between serotypes. PMID:26656072

  18. Combined Use of GPS and Accelerometry Reveals Fine Scale Three-Dimensional Foraging Behaviour in the Short-Tailed Shearwater.

    PubMed

    Berlincourt, Maud; Angel, Lauren P; Arnould, John P Y

    2015-01-01

    Determining the foraging behaviour of free-ranging marine animals is fundamental for assessing their habitat use and how they may respond to changes in the environment. However, despite recent advances in bio-logging technology, collecting information on both at-sea movement patterns and activity budgets still remains difficult in small pelagic seabird species due to the constraints of instrument size. The short-tailed shearwater, the most abundant seabird species in Australia (ca 23 million individuals), is a highly pelagic procellariiform. Despite its ecological importance to the region, almost nothing is known about its at-sea behaviour, in particular, its foraging activity. Using a combination of GPS and tri-axial accelerometer data-loggers, the fine scale three-dimensional foraging behaviour of 10 breeding individuals from two colonies was investigated. Five at-sea behaviours were identified: (1) resting on water, (2) flapping flight, (3) gliding flight, (4) foraging (i.e., surface foraging and diving events), and (5) taking-off. There were substantial intra- and inter- individual variations in activity patterns, with individuals spending on average 45.8% (range: 17.1-70.0%) of time at sea resting on water and 18.2% (range: 2.3-49.6%) foraging. Individuals made 76.4 ± 65.3 dives (range: 8-237) per foraging trip (mean duration 9.0 ± 1.9 s), with dives also recorded during night-time. With the continued miniaturisation of recording devices, the use of combined data-loggers could provide us with further insights into the foraging behaviour of small procellariiforms, helping to better understand interactions with their prey.

  19. Fine-Scale Cartography of Human Impacts along French Mediterranean Coasts: A Relevant Map for the Management of Marine Ecosystems

    PubMed Central

    Holon, Florian; Mouquet, Nicolas; Boissery, Pierre; Bouchoucha, Marc; Delaruelle, Gwenaelle; Tribot, Anne-Sophie; Deter, Julie

    2015-01-01

    Ecosystem services provided by oceans and seas support most human needs but are threatened by human activities. Despite existing maps illustrating human impacts on marine ecosystems, information remains either large-scale but rough and insufficient for stakeholders (1 km² grid, lack of data along the coast) or fine-scale but fragmentary and heterogeneous in methodology. The objectives of this study are to map and quantify the main pressures exerted on near-coast marine ecosystems, at a large spatial scale though in fine and relevant resolution for managers (one pixel = 20 x 20 m). It focuses on the French Mediterranean coast (1,700 km of coastline including Corsica) at a depth of 0 to 80 m. After completing and homogenizing data presently available under GIS on the bathymetry and anthropogenic pressures but also on the seabed nature and ecosystem vulnerability, we provide a fine modeling of the extent and impacts of 10 anthropogenic pressures on marine habitats. The considered pressures are man-made coastline, boat anchoring, aquaculture, urban effluents, industrial effluents, urbanization, agriculture, coastline erosion, coastal population and fishing. A 1:10 000 continuous habitat map is provided considering 11 habitat classes. The marine bottom is mostly covered by three habitats: infralittoral soft bottom, Posidonia oceanica meadows and circalittoral soft bottom. Around two thirds of the bottoms are found within medium and medium high cumulative impact categories. Seagrass meadows are the most impacted habitats. The most important pressures (in area and intensity) are urbanization, coastal population, coastal erosion and man-made coastline. We also identified areas in need of a special management interest. This work should contribute to prioritize environmental needs, as well as enhance the development of indicators for the assessment of the ecological status of coastal systems. It could also help better apply and coordinate management measures at a relevant

  20. Seasonal effects and fine-scale population dynamics of Aedes taeniorhynchus, a major disease vector in the Galapagos Islands.

    PubMed

    Bataille, Arnaud; Cunningham, Andrew A; Cruz, Marilyn; Cedeno, Virna; Goodman, Simon J

    2010-10-01

    Characterization of the fine-scale population dynamics of the mosquito Aedes taeniorhynchus is needed to improve our understanding of its role as a disease vector in the Galapagos Islands. We used microsatellite data to assess the genetic structure of coastal and highland mosquito populations and patterns of gene flow between the two habitats through time on Santa Cruz Island. In addition, we assessed possible associations of mosquito abundance and genetic diversity with environmental variables. The coastal and highland mosquito populations were highly differentiated from each other all year round, with some gene flow detected only during periods of increased precipitation. The results support the hypothesis that selection arising from ecological differences between habitats is driving adaptation and divergence in A. taeniorhynchus, and maintaining long-term genetic differentiation of the populations against gene flow. The highland and lowland populations may constitute an example of incipient speciation in progress. Highland populations were characterized by lower observed heterozygosity and allelic richness, suggesting a founder effect and/or lower breeding site availability in the highlands. A lack of reduction in genetic diversity over time in highland populations suggests that they survive dry periods as dormant eggs. Association between mosquito abundance and precipitation was strong in the highlands, whereas tide height was the main factor affecting mosquito abundance on the coast. Our findings suggests differences in the infection dynamics of mosquito-borne parasites in the highlands compared to the coast, and a higher risk of mosquito-driven disease spread across these habitats during periods of increased precipitation.

  1. Spatial spin-up of fine scales in a regional climate model simulation driven by low-resolution boundary conditions

    NASA Astrophysics Data System (ADS)

    Matte, Dominic; Laprise, René; Thériault, Julie M.; Lucas-Picher, Philippe

    2017-07-01

    In regional climate modelling, it is well known that domains should be neither too large to avoid a large departure from the driving data, nor too small to provide a sufficient distance from the lateral inflow boundary to allow the full development of the small-scale (SS) features permitted by the finer resolution. Although most practitioners of dynamical downscaling are well aware that the jump of resolution between the lateral boundary condition (LBC) driving data and the nested regional climate model affects the simulated climate, this issue has not been fully investigated. In principle, as the jump of resolution becomes larger, the region of interest in the limited-area domain should be located further away from the lateral inflow boundary to allow the full development of the SS features. A careless choice of domain might result in a suboptimal use of the full finer resolution potential to develop fine-scale features. To address this issue, regional climate model (RCM) simulations using various resolution driving data are compared following the perfect-prognostic Big-Brother protocol. Several experiments were carried out to evaluate the width of the spin-up region (i.e. the distance between the lateral inflow boundary and the domain of interest required for the full development of SS transient eddies) as a function of the RCM and LBC resolutions, as well as the resolution jump. The spin-up distance turns out to be a function of the LBC resolution only, independent of the RCM resolution. When varying the RCM resolution for a given resolution jump, it is found that the spin-up distance corresponds to a fixed number of RCM grid points that is a function of resolution jump only. These findings can serve a useful purpose to guide the choice of domain and RCM configuration for an optimal development of the small scales allowed by the increased resolution of the nested model.

  2. Changes in Oscillatory Brain Networks after Lexical Tone Training

    PubMed Central

    Kaan, Edith; Wayland, Ratree; Keil, Andreas

    2013-01-01

    Learning foreign speech contrasts involves creating new representations of sound categories in memory. This formation of new memory representations is likely to involve changes in neural networks as reflected by oscillatory brain activity. To explore this, we conducted time-frequency analyses of electro-encephalography (EEG) data recorded in a passive auditory oddball paradigm using Thai language tones. We compared native speakers of English (a non-tone language) and native speakers of Mandarin Chinese (a tone language), before and after a two-day laboratory training. Native English speakers showed a larger gamma-band power and stronger alpha-band synchrony across EEG channels than the native Chinese speakers, especially after training. This is compatible with the view that forming new speech categories on the basis of unfamiliar perceptual dimensions involves stronger gamma activity and more coherent activity in alpha-band networks than forming new categories on the basis of familiar dimensions. PMID:24961423

  3. Oscillatory Flow Testing in a Sandbox - Towards Oscillatory Hydraulic Tomography

    NASA Astrophysics Data System (ADS)

    Zhou, Y.; Lim, D.; Cupola, F.; Cardiff, M. A.

    2014-12-01

    Detailed knowledge of subsurface hydraulic properties is important for predicting groundwater flow and contaminant transport. The spatial variation of hydraulic properties in the shallow subsurface has been extensively studied in the past two decades. A recent approach to characterize subsurface properties is hydraulic tomography, in which pressure data from multiple constant-rate pumping tests is inverted using a numerical model. Many laboratory sandbox studies have explored the performance of hydraulic tomography under different controlled conditions and shown that detailed heterogeneity information can be extracted (Liu et al., 2002, Illman et al., 2007, 2008, 2010a, 2010b, Liu et al., 2007, 2008, Xiang et al., 2009, Yin and Illman, 2009, Liu and Kitanidis, 2011, Berg and Illman, 2011a). Recently, Cardiff et al. (2013) proposed a modified approach of Oscillatory Hydraulic Tomography (OHT) - in which periodic pumping signals of different frequencies are used for aquifer stimulation - to characterize aquifer properties. The potential advantages of OHT over traditional hydraulic tomography include: 1) no net injection or extraction of water; 2) little movement of existing contamination; 3) minimal impact of model boundary conditions; and 4) robust extraction of oscillatory signals from noisy data. To evaluate the premise of OHT, we built a highly-instrumented 2-D laboratory sandbox and record pressure responses to periodic pumping tests. In our setup, the laboratory sandbox is filled with sand of known hydraulic properties, and we measure aquifer responses at a variety of testing frequencies. The signals recorded are processed using Fourier-domain analysis, and compared against expected results under linear (Darcian) theory. The responses are analyzed using analytical and numerical models, which provide key insights as to: 1) how "effective" hydraulic properties estimated using homogeneous models are associated with aquifer heterogeneity; and 2) how OHT is able to

  4. Not so different after all: The same oscillatory processes support different types of attention.

    PubMed

    Frey, Julia Natascha; Ruhnau, Philipp; Weisz, Nathan

    2015-11-11

    Scientific research from the last two decades has provided a vast amount of evidence that brain oscillations reflect physiological activity enabling diverse cognitive processes. The goal of this review is to give a broad empirical and conceptual overview of how ongoing oscillatory activity may support attention processes. Keeping in mind that definitions of cognitive constructs like attention are prone to being blurry and ambiguous, the present review focuses mainly on the neural correlates of 'top-down' attention deployment. In particular, we will discuss modulations of (ongoing) oscillatory activity during spatial, temporal, selective, and internal attention. Across these seemingly distinct attentional domains, we will summarize studies showing the involvement of two oscillatory processes observed during attention deployment: power modulations mainly in the alpha band, and phase modulations in lower frequency bands. This article is part of a Special Issue entitled SI: Prediction and Attention.

  5. Fluence dependent oscillatory amorphization and recrystallization in ion irradiation

    NASA Astrophysics Data System (ADS)

    Banu, Nasrin; Satpati, B.; Dev, B. N.

    2017-09-01

    Ion-beam-induced amorphization and recrystallization are well-known phenomena. At a constant ion flux, there is a substrate temperature TR such that, for T < TR the irradiation produces amorphization, whereas for T > TR, it produces recrystallization. However, both the processes do not happen at a given substrate temperature. Here we present a novel phenomenon of ion fluence dependent oscillatory amorphization and recrystallization in silicon at room temperature in a Si(5 nm)/Ni(15 nm)/Si system. Before the deposition of Ni on Si, a buffer Si layer was deposited on the Si substrate. Ion irradiation was carried out with 1 MeV Si+ ions in the fluence range 1 × 1014-3 × 1017 ions/cm2. At a fluence of 5 × 1016 ions/cm2, Si is amorphous up to a depth of ∼1.4 μm. However, at a fluence of 1 × 1017 ions/cm2 two narrow bands of recrystallized (rc) Si are formed within the amorphized Si. At 2 × 1017 ions/cm2 these rc-Si bands become amorphous again. At 3 × 1017 ions/cm2 the broader rc band reappears. This oscillatory amorphization/recrystallization behaviour is Ni-mediated. Energy dispersive X-ray map of Ni shows Ni accumulation at the top of the rc-Si bands. The top of the broader rc band is actually the buffer-Si/substrate-Si interface. TRIM simulation shows the appearance of a Ni-displacement-induced vacancy peak at the position of the narrow rc-Si band. Accumulation of Ni in these regions is associated with the recrystallization process. The Ni layer, with incorporation of Si, also passes through amorphization and recrystallization. At the highest fluence η-NiSi nanocrystals are formed in the Ni layer.

  6. Collective phase description of oscillatory convection

    SciTech Connect

    Kawamura, Yoji; Nakao, Hiroya

    2013-12-15

    We formulate a theory for the collective phase description of oscillatory convection in Hele-Shaw cells. It enables us to describe the dynamics of the oscillatory convection by a single degree of freedom which we call the collective phase. The theory can be considered as a phase reduction method for limit-cycle solutions in infinite-dimensional dynamical systems, namely, stable time-periodic solutions to partial differential equations, representing the oscillatory convection. We derive the phase sensitivity function, which quantifies the phase response of the oscillatory convection to weak perturbations applied at each spatial point, and analyze the phase synchronization between two weakly coupled Hele-Shaw cells exhibiting oscillatory convection on the basis of the derived phase equations.

  7. Parametric oscillatory instability in a signal-recycled LIGO interferometer

    SciTech Connect

    Vyatchanin, S P; Strigin, S E

    2007-12-31

    The undesirable effect of parametric oscillatory instability in a LIGO (Laser Interferometer Gravitational-Wave Observatory) laser gravitational-wave antenna with a signal-recirculation mirror is analysed in detail. The instability is manifested in excitation of the Stokes optical mode and elastic mechanical mode of the mirror. It is shown that, if the eigenfrequencies of Fabry-Perot resonators in the interferometer arms are different, the parametric instability is quite small due to a small passband band width. (fifth seminar in memory of d.n. klyshko)

  8. Frontal oscillatory dynamics predict feedback learning and action adjustment.

    PubMed

    van de Vijver, Irene; Ridderinkhof, K Richard; Cohen, Michael X

    2011-12-01

    Frontal oscillatory dynamics in the theta (4-8 Hz) and beta (20-30 Hz) frequency bands have been implicated in cognitive control processes. Here we investigated the changes in coordinated activity within and between frontal brain areas during feedback-based response learning. In a time estimation task, participants learned to press a button after specific, randomly selected time intervals (300-2000 msec) using the feedback after each button press (correct, too fast, too slow). Consistent with previous findings, theta-band activity over medial frontal scalp sites (presumably reflecting medial frontal cortex activity) was stronger after negative feedback, whereas beta-band activity was stronger after positive feedback. Theta-band power predicted learning only after negative feedback, and beta-band power predicted learning after positive and negative feedback. Furthermore, negative feedback increased theta-band intersite phase synchrony (a millisecond resolution measure of functional connectivity) among right lateral prefrontal, medial frontal, and sensorimotor sites. These results demonstrate the importance of frontal theta- and beta-band oscillations and intersite communication in the realization of reinforcement learning.

  9. Oscillatory Serotonin Function in Depression

    PubMed Central

    Salomon, Ronald M.; Cowan, Ronald L.

    2013-01-01

    Oscillations in brain activities with periods of minutes to hours may be critical for normal mood behaviors. Ultradian (faster than circadian) rhythms of mood behaviors and associated central nervous system activities are altered in depression. Recent data suggest that ultradian rhythms in serotonin (5HT) function also change in depression. In two separate studies, 5HT metabolites in cerebrospinal fluid (CSF) were measured every 10 m for 24 h before and after chronic antidepressant treatment. Antidepressant treatments were associated with enhanced ultradian amplitudes of CSF metabolite levels. Another study used resting-state functional magnetic resonance imaging (fMRI)to measure amplitudes of dorsal raphé activation cycles following sham or active dietary depletions of the 5HT precursor (tryptophan). During depletion, amplitudes of dorsal raphé activation cycles increased with rapid 6 s periods (about 0.18 Hz)while functional connectivity weakened between dorsal raphé and thalamus at slower periods of 20 s (0.05 Hz). A third approach studied MDMA (ecstasy) users because of their chronically diminished 5HT function compared to non-MDMA polysubstance users (Karageorgiou et al., 2009). Compared to a non-MDMA using cohort, MDMA users showed diminished fMRI intra-regional coherence in motor regions along with altered functional connectivity, again suggesting effects of altered 5HT oscillatory function. These data support a hypothesis that qualities of ultradian oscillations in 5HT function may critically influence moods and behaviors. Dysfunctional 5HT rhythms in depression may be a common endpoint and biomarker for depression, linking dysfunction of slow brain network oscillators to 5HT mechanisms affected by commonly available treatments. 5HT oscillatory dysfunction may define illness subtypes and predict responses to serotonergic agents. Further studies of 5HT oscillations in depression are indicated. PMID:23592367

  10. Oscillatory Reinstatement Enhances Declarative Memory.

    PubMed

    Javadi, Amir-Homayoun; Glen, James C; Halkiopoulos, Sara; Schulz, Mei; Spiers, Hugo J

    2017-10-11

    Declarative memory recall is thought to involve the reinstatement of neural activity patterns that occurred previously during encoding. Consistent with this view, greater similarity between patterns of activity recorded during encoding and retrieval has been found to predict better memory performance in a number of studies. Recent models have argued that neural oscillations may be crucial to reinstatement for successful memory retrieval. However, to date, no causal evidence has been provided to support this theory, nor has the impact of oscillatory electrical brain stimulation during encoding and retrieval been assessed. To explore this we used transcranial alternating current stimulation over the left dorsolateral prefrontal cortex of human participants [n = 70, 45 females; age mean (SD) = 22.12 (2.16)] during a declarative memory task. Participants received either the same frequency during encoding and retrieval (60-60 or 90-90 Hz) or different frequencies (60-90 or 90-60 Hz). When frequencies matched there was a significant memory improvement (at both 60 and 90 Hz) relative to sham stimulation. No improvement occurred when frequencies mismatched. Our results provide support for the role of oscillatory reinstatement in memory retrieval.SIGNIFICANCE STATEMENT Recent neurobiological models of memory have argued that large-scale neural oscillations are reinstated to support successful memory retrieval. Here we used transcranial alternating current stimulation (tACS) to test these models. tACS has recently been shown to induce neural oscillations at the frequency stimulated. We stimulated over the left dorsolateral prefrontal cortex during a declarative memory task involving learning a set of words. We found that tACS applied at the same frequency during encoding and retrieval enhances memory. We also find no difference between the two applied frequencies. Thus our results are consistent with the proposal that reinstatement of neural oscillations during retrieval

  11. Characterizing Oscillatory Bursts in Single-Trial EEG Data

    NASA Technical Reports Server (NTRS)

    Knuth, K. H.; Shah, A. S.; Lakatos, P.; Schroeder, C. E.

    2004-01-01

    Oscillatory bursts in numerous bands ranging from low (theta) to high frequencies (e.g., gamma) undoubtedly play an important role in cortical dynamics. Largely because of the inadequacy of existing analytic techniques. however, oscillatory bursts and their role in cortical processing remains poorly understood. To study oscillatory bursts effectively one must be able to isolate them and characterize them in the single trial. We describe a series of straightforward analysis techniques that produce useful indices of burst characteristics. First, stimulus-evoked responses are estimated using Differentially Variable Component Analysis (dVCA), and are subtracted from the single-trial. The single-trial characteristics of the evoked responses are stored to identify possible correlations with burst activity. Time-frequency (T-F), or wavelet, analyses are then applied to the single trial residuals. While T-F plots have been used in recent studies to identify and isolate bursts, we go further by fitting each burst in the T-F plot with a two-dimensional Gaussian. This provides a set of burst characteristics, such as, center time. burst duration, center frequency. frequency dispersion. and amplitude, all of which contribute to the accurate characterization of the individual burst. The burst phase can also be estimated. Burst characteristics can be quantified with several standard techniques (e.g.. histogramming and clustering), as well as Bayesian techniques (e.g., blocking) to allow a more parametric description analysis of the characteristics of oscillatory bursts, and the relationships of specific parameters to cortical excitability and stimulus integration.

  12. Characterizing Oscillatory Bursts in Single-Trial EEG Data

    NASA Technical Reports Server (NTRS)

    Knuth, K. H.; Shah, A. S.; Lakatos, P.; Schroeder, C. E.

    2004-01-01

    Oscillatory bursts in numerous bands ranging from low (theta) to high frequencies (e.g., gamma) undoubtedly play an important role in cortical dynamics. Largely because of the inadequacy of existing analytic techniques. however, oscillatory bursts and their role in cortical processing remains poorly understood. To study oscillatory bursts effectively one must be able to isolate them and characterize them in the single trial. We describe a series of straightforward analysis techniques that produce useful indices of burst characteristics. First, stimulus-evoked responses are estimated using Differentially Variable Component Analysis (dVCA), and are subtracted from the single-trial. The single-trial characteristics of the evoked responses are stored to identify possible correlations with burst activity. Time-frequency (T-F), or wavelet, analyses are then applied to the single trial residuals. While T-F plots have been used in recent studies to identify and isolate bursts, we go further by fitting each burst in the T-F plot with a two-dimensional Gaussian. This provides a set of burst characteristics, such as, center time. burst duration, center frequency. frequency dispersion. and amplitude, all of which contribute to the accurate characterization of the individual burst. The burst phase can also be estimated. Burst characteristics can be quantified with several standard techniques (e.g.. histogramming and clustering), as well as Bayesian techniques (e.g., blocking) to allow a more parametric description analysis of the characteristics of oscillatory bursts, and the relationships of specific parameters to cortical excitability and stimulus integration.

  13. NetView: a high-definition network-visualization approach to detect fine-scale population structures from genome-wide patterns of variation.

    PubMed

    Neuditschko, Markus; Khatkar, Mehar S; Raadsma, Herman W

    2012-01-01

    High-throughput sequencing and single nucleotide polymorphism (SNP) genotyping can be used to infer complex population structures. Fine-scale population structure analysis tracing individual ancestry remains one of the major challenges. Based on network theory and recent advances in SNP chip technology, we investigated an unsupervised network clustering method called Super Paramagnetic Clustering (Spc). When applied to whole-genome marker data it identifies the natural divisions of groups of individuals into population clusters without use of prior ancestry information. Furthermore, we optimised an analysis pipeline called NetView, a high-definition network visualization, starting with computation of genetic distance, followed clustering using Spc and finally visualization of clusters with Cytoscape. We compared NetView against commonly used methodologies including Principal Component Analyses (PCA) and a model-based algorithm, Admixture, on whole-genome-wide SNP data derived from three previously described data sets: simulated (2.5 million SNPs, 5 populations), human (1.4 million SNPs, 11 populations) and cattle (32,653 SNPs, 19 populations). We demonstrate that individuals can be effectively allocated to their correct population whilst simultaneously revealing fine-scale structure within the populations. Analyzing the human HapMap populations, we identified unexpected genetic relatedness among individuals, and population stratification within the Indian, African and Mexican samples. In the cattle data set, we correctly assigned all individuals to their respective breeds and detected fine-scale population sub-structures reflecting different sample origins and phenotypes. The NetView pipeline is computationally extremely efficient and can be easily applied on large-scale genome-wide data sets to assign individuals to particular populations and to reproduce fine-scale population structures without prior knowledge of individual ancestry. NetView can be used on any

  14. Beyond habitat requirements: individual fine-scale site fidelity in a colony of the Galapagos sea lion (Zalophus wollebaeki) creates conditions for social structuring.

    PubMed

    Wolf, Jochen B W; Trillmich, Fritz

    2007-06-01

    Site fidelity has been widely discussed, but rarely been related explicitly to a species' social context. This is surprising, as fine-scale site fidelity constitutes an important structural component in animal societies by setting limits to an individual's social interaction space. The study of fine-scale site fidelity is complicated by the fact that it is inextricably linked to patterns of habitat use. We here document fine-scale site fidelity in the Galapagos sea lion (Zalophus wollebaeki) striving to disentangle these two aspects of spatial behaviour. Regardless of sex and age, all individuals used small, cohesive home ranges, which were stable in size across the reproductive and non-reproductive season. Home ranges showed a large individual component and did not primarily reflect age- or sex-specific habitat requirements. Site specificity could be illustrated up to a resolution of several metres. Long-term site fidelity was indicated by home range persistence over 3 years and the degree of site fidelity was unaffected by habitat, but showed seasonal differences: it was lower between reproductive and non-reproductive periods than between reproductive seasons. We further examined static and social interaction within mother-offspring pairs, which constitute a central social unit in most mammalian societies. Regardless of the occupied habitat type, adult females with offspring had smaller home range sizes than non-breeding females, demonstrating the importance of spatial predictability for mother-offspring pairs that recurrently have to reunite after females' foraging sojourns. While social interaction with the mother dropped to naught in both sexes after weaning, analysis of static interaction suggested female-biased home range inheritance. Dispersal decisions were apparently not based on habitat quality, but determined by the offspring's sex. We discuss the implication of observed fine-scale site fidelity patterns on habitat use, dispersal decisions and social

  15. Fine-Scale Microclimatic Variation Can Shape the Responses of Organisms to Global Change in Both Natural and Urban Environments.

    PubMed

    Pincebourde, Sylvain; Murdock, Courtney C; Vickers, Mathew; Sears, Michael W

    2016-07-01

    abilities of ectotherms in setting their overall performance. We used a random walk framework to show that the thermal heterogeneity allows a more precise behavioral thermoregulation and a narrower temperature distribution of the ectotherm compared to less heterogeneous microhabitats. Finally, we discuss the potential impacts of global change on the fine scale mosaics of microclimates. The amplitude of change may differ between spatial scales. In heterogeneous microhabitats, the amplitude of change at micro-scale, caused by atmospheric warming, can be substantial while it can be limited at the local and landscape scales. We suggest that the warming signal will influence species performance and biotic interactions by modulating the mosaic of microclimates. © The Author 2016. Published by Oxford University Press on behalf of the Society for Integrative and Comparative Biology. All rights reserved. For permissions please email: journals.permissions@oup.com.

  16. Fine-scale geographic variation in photosynthetic-related traits of Picea glauca seedlings indicates local adaptation to climate.

    PubMed

    Benomar, Lahcen; Lamhamedi, Mohammed S; Villeneuve, Isabelle; Rainville, André; Beaulieu, Jean; Bousquet, Jean; Margolis, Hank A

    2015-08-01

    Climate-related variations in functional traits of boreal tree species can result both from physiological acclimation and genetic adaptation of local populations to their biophysical environment. To improve our understanding and prediction of the physiological and growth responses of populations to climate change, we studied the role of climate of seed origin in determining variations in functional traits and its implications for tree improvement programs for a commonly reforested boreal conifer, white spruce (Picea glauca (Moench) Voss). We evaluated growth, root-to-shoot ratio (R/S), specific leaf area (SLA), needle nitrogen (N(mass)), total non-structural carbohydrates (NSC) and photosynthetic traits of 3-year-old seedlings in a greenhouse experiment using seed from six seed orchards (SO) representing the different regions where white spruce is reforested in Québec. Height and total dry mass (TDM) were positively correlated with photosynthetic capacity (A(max)), stomatal conductance (g(s)) and mesophyll conductance (g(m)). Total dry mass, but not height growth, was strongly correlated with latitude of seed origin (SO) and associated climate variables. A(max), g(s), g(m) and more marginally, photosynthetic nitrogen-use efficiency (PNUE) were positively associated with the mean July temperature of the SO, while water use efficiency (WUE) was negatively associated. Maximum rates of carboxylation (V(cmax)), maximum rates of electron transport (J(max)), SLA, N(mass), NSC and R/S showed no pattern. Our results did not demonstrate a higher Amax for northern seed orchards, although this has been previously hypothesized as an adaptation mechanism for maintaining carbon uptake in northern regions. We suggest that gs, gm, WUE and PNUE are the functional traits most associated with fine-scale geographic clines and with the degree of local adaptation of white spruce populations to their biophysical environments. These geographic patterns may reflect in situ adaptive genetic

  17. Two behavioural traits promote fine-scale species segregation and moderate hybridisation in a recovering sympatric fur seal population

    PubMed Central

    2010-01-01

    Background In systems where two or more species experience secondary contact, behavioural factors that regulate interspecific gene flow may be important for maintaining species boundaries and reducing the incidence of hybridisation. At subantarctic Macquarie Island, two species of fur seal breed in close proximity to one another, hybridise at very high levels (up to 21% of hybrid pups are born annually), yet retain discrete gene pools. Using spatial and genetic information collected for pups and adults over twelve years, we assessed two behavioural traits - inter-annual site fidelity and differences in habitat use between the species - as possible contributors to the maintenance of this species segregation. Further, we explored the breakdown of these traits in pure-species individuals and hybrids. Results We found virtually complete spatial segregation of the parental species, with only one exception; a single territory that contained adults of both species and also the highest concentration of hybrid pups. The spatial distribution of each species was closely linked to habitat type (pebbled vs boulder beaches), with members of each species breeding almost exclusively on one type or the other but hybrids breeding on both or at the junction between habitats. Inter-annual site fidelity was high for both sexes of pure-species adults, with 66% of females and all males returning to the same territory or a neighbouring one in different years. An important consequence for pure females of breeding on the 'wrong' habitat type, and thus in a heterospecific aggregation, was the production of hybrid pups. Low habitat fidelity of hybrid females facilitated bi-directional backcrossing, resulting in more diverse hybrid offspring. Conclusion In a disturbed system where two sympatric fur seal species breed in close proximity, discrete gene pools are retained by extremely fine-scale and strong spatial segregation of the species. Two behavioural traits were found to be important in

  18. Fine scale Spatial-temporal cluster analysis for the infection risk of Schistosomiasis japonica using space-time scan statistics.

    PubMed

    Gao, Feng-hua; Abe, Eniola Michael; Li, Shi-zhu; Zhang, Li-juan; He, Jia-Chang; Zhang, Shi-qing; Wang, Tian-ping; Zhou, Xiao-nong; Gao, Jing

    2014-12-10

    Marching towards the elimination of schistosomiasis in China, both the incidence and prevalence have witnessed profound decline over the past decades, with the strategy shifting from morbidity control to transmission control. The current challenge is to find out hotspots of transmission risk for precise targeted control in low-prevalence areas. This study assessed the risk at the village level, using the spatial and temporal characteristics of Schistosomiasis japonica in Anhui province from 2006 to 2012. The comprehensive database was generated from annual surveillance data at village level in Anhui province between 2006 and 2012, comprising schistosomiasis prevalence among humans and cattle, occurrence rate of infected environments and incidence rate of acute schistosomiasis. The database parameters were matched with geographic data of the study area and fine scale spatial-temporal cluster analysis based on retrospective space-time scan statistics was used to assess the clustering pattern of schistosomiasis. The analysis was conducted by using SaTScan 9.1.1 and ArcGIS 10.0. A spatial statistical modelling was carried out to determine the spatial dependency of prevalence of human infection by using Geoda 1.4.3. A pronounced decline was found in the prevalence of human infection, cattle infection, occurrence rate of environment with infected vector snails and incidence rate of acute schistosomiasis from 2006 to 2012 by 48.6%, 71.5%, 91.9% and 96.4%, respectively. Meanwhile, all 4 indicators showed a statistically significant clustering pattern both in time and space, with a total of 16, 6, 8 and 4 corresponding clustering foci found respectively. However, the number of clustering foci declined with time, and none was found after year 2010. All clustering foci were mainly distributed along the Yangtze River and its connecting branches. The result shows that there is a direct spatial relationship between prevalence of human infection and the other indicators. A

  19. Spatially explicit multi-threat assessment of food tree species in Burkina Faso: A fine-scale approach.

    PubMed

    Gaisberger, Hannes; Kindt, Roeland; Loo, Judy; Schmidt, Marco; Bognounou, Fidèle; Da, Sié Sylvestre; Diallo, Ousmane Boukary; Ganaba, Souleymane; Gnoumou, Assan; Lompo, Djingdia; Lykke, Anne Mette; Mbayngone, Elisée; Nacoulma, Blandine Marie Ivette; Ouedraogo, Moussa; Ouédraogo, Oumarou; Parkouda, Charles; Porembski, Stefan; Savadogo, Patrice; Thiombiano, Adjima; Zerbo, Guibien; Vinceti, Barbara

    2017-01-01

    Over the last decades agroforestry parklands in Burkina Faso have come under increasing demographic as well as climatic pressures, which are threatening indigenous tree species that contribute substantially to income generation and nutrition in rural households. Analyzing the threats as well as the species vulnerability to them is fundamental for priority setting in conservation planning. Guided by literature and local experts we selected 16 important food tree species (Acacia macrostachya, Acacia senegal, Adansonia digitata, Annona senegalensis, Balanites aegyptiaca, Bombax costatum, Boscia senegalensis, Detarium microcarpum, Lannea microcarpa, Parkia biglobosa, Sclerocarya birrea, Strychnos spinosa, Tamarindus indica, Vitellaria paradoxa, Ximenia americana, Ziziphus mauritiana) and six key threats to them (overexploitation, overgrazing, fire, cotton production, mining and climate change). We developed a species-specific and spatially explicit approach combining freely accessible datasets, species distribution models (SDMs), climate models and expert survey results to predict, at fine scale, where these threats are likely to have the greatest impact. We find that all species face serious threats throughout much of their distribution in Burkina Faso and that climate change is predicted to be the most prevalent threat in the long term, whereas overexploitation and cotton production are the most important short-term threats. Tree populations growing in areas designated as 'highly threatened' due to climate change should be used as seed sources for ex situ conservation and planting in areas where future climate is predicting suitable habitats. Assisted regeneration is suggested for populations in areas where suitable habitat under future climate conditions coincides with high threat levels due to short-term threats. In the case of Vitellaria paradoxa, we suggest collecting seed along the northern margins of its distribution and considering assisted regeneration in the

  20. Fine Scale Structure of Low and Ultra-Low Velocity Patches in the Lowermost Mantle: Some Case Studies

    NASA Astrophysics Data System (ADS)

    Yuan, K.; Romanowicz, B. A.; French, S.

    2015-12-01

    The lowermost part of the mantle, which is roughly halfway to the center of the earth, plays a key role as a thermal and chemical boundary layer between the solid, silicate mantle and fluid, iron outer core. Constraining the seismic velocity structure in this region provides important insights on mantle dynamics, and core-mantle interactions. Recently, global shear wave velocity tomography has confirmed the presence of broad plume conduits extending vertically through the lower mantle in the vicinity of major hotspots (SEMUCB-WM1, French and Romanowicz, 2015). These conduits are rooted in D" in patches of strongly reduced shear velocity, at least some of which, such as Hawaii, appear to contain known ultra low velocity zones (e.g. Cottaar and Romanowicz, 2012). We seek to determine whether these patches generally contain ULVZs, and to contrast them with less extreme structures such as the PERM anomaly (Lekic et al., 2012). Because global tomography cannot resolve such fine scale structure, we apply forward modeling of higher frequency (10-20s) Sdiff waveforms in 3D complex structures using the Spectral Element Method. We focus on Iceland, Hawaii and the PERM anomaly, and Sdiff observations at USArray and/or dense broadband arrays in Europe. In all three cases, Sdiff waveforms are clearly distorted by these anomalies, with either a complex coda and/or evidence for amplitude focusing. As a start, we design simple cylindrical models of shear velocity reduction, and contrast the best fitting ones at each location considered in terms of diameter, height above the core-mantle boundary and strength of velocity reduction. We refine previously obtained models for Hawaii and the Perm Anomaly. For Iceland, the waveforms show a strong azimuthally dependent post-cursor, with maximum travel time delay of ~20s and focusing effects. The preliminary best fitting model shows a structure of 700km in diameter, ~15% reduction in shear wave velocity, extending ~40 km above the core

  1. Elastic Full Waveform Inversion reveals the fine-scale structure of Axial Volcano on the Juan de Fuca Ridge

    NASA Astrophysics Data System (ADS)

    Arnulf, A. F.; Harding, A. J.; Kent, G.

    2012-12-01

    Axial volcano (sometimes referred to as "Axial seamount" or "Axial") is located at 46N, 130W at the intersection of the Juan de Fuca Ridge and the Cobb-Eickelberg seamount chain. It is the most recent eruptive center of the Cobb hotspot, which last erupted in 2011. The volcano rises ~700 m above the adjacent ridge axis and its summit features a U-shaped caldera open to the southeast, which hosts an active hydrothermal field and very young lava flows. Located at the junction of a mid-ocean ridge and a volcanic hotspot, Axial volcano is atypical and its internal structure remains poorly understood. Here, we present results from an elastic full waveform inversion (FWI) along multiple seismic lines that span the whole volcano. We have used a multi-stage FWI, inverting successively wide-angle reflections and refractions arrivals from downward extrapolated streamer data, then windowed short offset reflections from the underlying magma chamber. Our final models show fine scale velocity structures with spatial resolutions of tens of meters. Our results indicate that Layer 2A thickness is extremely heterogeneous (350-900 m) within the volcano with abrupt vertical throws of >300 m beneath the caldera walls that suggests the tectonic thinning of a geologically defined Layer 2A. Interestingly, Layer 2A appears to be extremely thin beneath the active hydrothermal field and the most recent lava flows, on the southeast end of the caldera, where sheeted dikes might lay <100 m beneath the seafloor. On the other hand, the nearby caldera center is filled by successive lava sequences (~450 m thick) that further appear to be micro faulted, suggesting a constant interplay between magmatic and tectonic processes. Surface velocities show limited variation over the whole volcano and may suggest relative recent formation, considering the rapid increase in layer 2A velocity with age. Finally, our velocity structures image a wide and complex magma chamber system beneath the volcano at depth

  2. Spatially explicit multi-threat assessment of food tree species in Burkina Faso: A fine-scale approach

    PubMed Central

    Kindt, Roeland; Loo, Judy; Schmidt, Marco; Bognounou, Fidèle; Da, Sié Sylvestre; Diallo, Ousmane Boukary; Ganaba, Souleymane; Gnoumou, Assan; Lompo, Djingdia; Lykke, Anne Mette; Mbayngone, Elisée; Nacoulma, Blandine Marie Ivette; Ouedraogo, Moussa; Ouédraogo, Oumarou; Parkouda, Charles; Porembski, Stefan; Savadogo, Patrice; Thiombiano, Adjima; Zerbo, Guibien; Vinceti, Barbara

    2017-01-01

    Over the last decades agroforestry parklands in Burkina Faso have come under increasing demographic as well as climatic pressures, which are threatening indigenous tree species that contribute substantially to income generation and nutrition in rural households. Analyzing the threats as well as the species vulnerability to them is fundamental for priority setting in conservation planning. Guided by literature and local experts we selected 16 important food tree species (Acacia macrostachya, Acacia senegal, Adansonia digitata, Annona senegalensis, Balanites aegyptiaca, Bombax costatum, Boscia senegalensis, Detarium microcarpum, Lannea microcarpa, Parkia biglobosa, Sclerocarya birrea, Strychnos spinosa, Tamarindus indica, Vitellaria paradoxa, Ximenia americana, Ziziphus mauritiana) and six key threats to them (overexploitation, overgrazing, fire, cotton production, mining and climate change). We developed a species-specific and spatially explicit approach combining freely accessible datasets, species distribution models (SDMs), climate models and expert survey results to predict, at fine scale, where these threats are likely to have the greatest impact. We find that all species face serious threats throughout much of their distribution in Burkina Faso and that climate change is predicted to be the most prevalent threat in the long term, whereas overexploitation and cotton production are the most important short-term threats. Tree populations growing in areas designated as ‘highly threatened’ due to climate change should be used as seed sources for ex situ conservation and planting in areas where future climate is predicting suitable habitats. Assisted regeneration is suggested for populations in areas where suitable habitat under future climate conditions coincides with high threat levels due to short-term threats. In the case of Vitellaria paradoxa, we suggest collecting seed along the northern margins of its distribution and considering assisted regeneration in

  3. Upper ocean fine-scale features in synthetic aperture radar imagery. Part I: Simultaneous satellite and in-situ measurements

    NASA Astrophysics Data System (ADS)

    Soloviev, A.; Maingot, C.; Matt, S.; Fenton, J.; Lehner, S.; Brusch, S.; Perrie, W. A.; Zhang, B.

    2011-12-01

    The new generation of synthetic aperture radar (SAR) satellites provides high resolution images that open new opportunities for identifying and studying fine features in the upper ocean. The problem is, however, that SAR images of the sea surface can be affected by atmospheric phenomena (rain cells, fronts, internal waves, etc.). Implementation of in-situ techniques in conjunction with SAR is instrumental for discerning the origin of features on the image. This work is aimed at the interpretation of natural and artificial features in SAR images. These features can include fresh water lenses, sharp frontal interfaces, internal wave signatures, as well as slicks of artificial and natural origin. We have conducted field experiments in the summer of 2008 and 2010 and in the spring of 2011 to collect in-situ measurements coordinated with overpasses of the TerraSAR-X, RADARSAT-2, ALOS PALSAR, and COSMO SkyMed satellites. The in-situ sensors deployed in the Straits of Florida included a vessel-mounted sonar and CTD system to record near-surface data on stratification and frontal boundaries, a bottom-mounted Nortek AWAC system to gather information on currents and directional wave spectra, an ADCP mooring at a 240 m isobath, and a meteorological station. A nearby NOAA NEXRAD Doppler radar station provided a record of rainfall in the area. Controlled releases of menhaden fish oil were performed from our vessel before several satellite overpasses in order to evaluate the effect of surface active materials on visibility of sea surface features in SAR imagery under different wind-wave conditions. We found evidence in the satellite images of rain cells, squall lines, internal waves of atmospheric and possibly oceanic origin, oceanic frontal interfaces and submesoscale eddies, as well as anthropogenic signatures of ships and their wakes, and near-shore surface slicks. The combination of satellite imagery and coordinated in-situ measurements was helpful in interpreting fine-scale

  4. Arctic fungal communities associated with roots of Bistorta vivipara do not respond to the same fine-scale edaphic gradients as the aboveground vegetation.

    PubMed

    Mundra, Sunil; Halvorsen, Rune; Kauserud, Håvard; Müller, Eike; Vik, Unni; Eidesen, Pernille B

    2015-03-01

    Soil conditions and microclimate are important determinants of the fine-scale distribution of plant species in the Arctic, creating locally heterogeneous vegetation. We hypothesize that root-associated fungal (RAF) communities respond to the same fine-scale environmental gradients as the aboveground vegetation, creating a coherent pattern between aboveground vegetation and RAF. We explored how RAF communities of the ectomycorrhizal (ECM) plant Bistorta vivipara and aboveground vegetation structure of arctic plants were affected by biotic and abiotic variables at 0.3-3.0-m scales. RAF communities were determined using pyrosequencing. Composition and spatial structure of RAF and aboveground vegetation in relation to collected biotic and abiotic variables were analysed by ordination and semi-variance analyses. The vegetation was spatially structured along soil C and N gradients, whereas RAF lacked significant spatial structure. A weak relationship between RAF community composition and the cover of two ECM plants, B. vivipara and S. polaris, was found, and RAF richness increased with host root length and root weight. Results suggest that the fine-scale spatial structure of RAF communities of B. vivipara and the aboveground vegetation are driven by different factors. At fine spatial scales, neighbouring ECM plants may affect RAF community composition, whereas soil nutrients gradients structure the vegetation.

  5. SYSTEMATIC MOTION OF FINE-SCALE JETS AND SUCCESSIVE RECONNECTION IN SOLAR CHROMOSPHERIC ANEMONE JET OBSERVED WITH THE SOLAR OPTICAL TELESCOPE/HINODE

    SciTech Connect

    Singh, K. A. P.; Nishida, K.; Shibata, K.; Isobe, H.

    2012-11-20

    The Solar Optical Telescope (SOT) on board Hinode allows observations with high spatiotemporal resolution and stable image quality. A {lambda}-shaped chromospheric anemone jet was observed in high resolution with SOT/Hinode. We found that several fine-scale jets were launched from one end of the footpoint to the other. These fine-scale jets ({approx}1.5-2.5 Mm) gradually move from one end of the footpoint to the other and finally merge into a single jet. This process occurs recurrently, and as time progresses the jet activity becomes more and more violent. The time evolution of the region below the jet in Ca II H filtergram images taken with SOT shows that various parts (or knots) appear at different positions. These bright knots gradually merge into each other during the maximum phase. The systematic motion of the fine-scale jets is observed when different knots merge into each other. Such morphology would arise due to the emergence of a three-dimensional twisted flux rope in which the axial component (or the guide field) appears in the later stages of the flux rope emergence. The partial appearance of the knots could be due to the azimuthal magnetic field that appears during the early stage of the flux rope emergence. If the guide field is strong and reconnection occurs between the emerging flux rope and an ambient magnetic field, this could explain the typical feature of systematic motion in chromospheric anemone jets.

  6. Systematic Motion of Fine-scale Jets and Successive Reconnection in Solar Chromospheric Anemone Jet Observed with the Solar Optical Telescope/Hinode

    NASA Astrophysics Data System (ADS)

    Singh, K. A. P.; Isobe, H.; Nishida, K.; Shibata, K.

    2012-11-01

    The Solar Optical Telescope (SOT) on board Hinode allows observations with high spatiotemporal resolution and stable image quality. A λ-shaped chromospheric anemone jet was observed in high resolution with SOT/Hinode. We found that several fine-scale jets were launched from one end of the footpoint to the other. These fine-scale jets (~1.5-2.5 Mm) gradually move from one end of the footpoint to the other and finally merge into a single jet. This process occurs recurrently, and as time progresses the jet activity becomes more and more violent. The time evolution of the region below the jet in Ca II H filtergram images taken with SOT shows that various parts (or knots) appear at different positions. These bright knots gradually merge into each other during the maximum phase. The systematic motion of the fine-scale jets is observed when different knots merge into each other. Such morphology would arise due to the emergence of a three-dimensional twisted flux rope in which the axial component (or the guide field) appears in the later stages of the flux rope emergence. The partial appearance of the knots could be due to the azimuthal magnetic field that appears during the early stage of the flux rope emergence. If the guide field is strong and reconnection occurs between the emerging flux rope and an ambient magnetic field, this could explain the typical feature of systematic motion in chromospheric anemone jets.

  7. Dynamics of cerium distribution during oscillatory extraction

    SciTech Connect

    Smirnov, A.V.; Afonin, M.A.; Sedov, V.M.

    1995-01-01

    The dynamics of the Ce distribution in a nonequilibrium extraction process are investigated. Results are presented for the extraction of Ce by tributylphosphate in organic diluents from an aqueous solution in which a Belousov-Zhabotinskii oscillating reaction is occurring. The time dependences of [Ce] in the organic phase of the oscillatory extraction system that are synchronous with the redox-potential dependences are obtained for the first time. The effect of the initial concentrations of Ce, oxidant, and organic substrate on the principal parameters of the oscillatory extraction, such as the frequency, amplitude, etc., is found. A conclusion is made about the ability to control an oscillatory extraction process.

  8. Higher fine-scale genetic structure in peripheral than in core populations of a long-lived and mixed-mating conifer - eastern white cedar (Thuja occidentalis L.)

    PubMed Central

    2012-01-01

    Background Fine-scale or spatial genetic structure (SGS) is one of the key genetic characteristics of plant populations. Several evolutionary and ecological processes and population characteristics influence the level of SGS within plant populations. Higher fine-scale genetic structure may be expected in peripheral than core populations of long-lived forest trees, owing to the differences in the magnitude of operating evolutionary and ecological forces such as gene flow, genetic drift, effective population size and founder effects. We addressed this question using eastern white cedar (Thuja occidentalis) as a model species for declining to endangered long-lived tree species with mixed-mating system. Results We determined the SGS in two core and two peripheral populations of eastern white cedar from its Maritime Canadian eastern range using six nuclear microsatellite DNA markers. Significant SGS ranging from 15 m to 75 m distance classes was observed in the four studied populations. An analysis of combined four populations revealed significant positive SGS up to the 45 m distance class. The mean positive significant SGS observed in the peripheral populations was up to six times (up to 90 m) of that observed in the core populations (15 m). Spatial autocorrelation coefficients and correlograms of single and sub-sets of populations were statistically significant. The extent of within-population SGS was significantly negatively correlated with all genetic diversity parameters. Significant heterogeneity of within-population SGS was observed for 0-15 m and 61-90 m between core and peripheral populations. Average Sp, and gene flow distances were higher in peripheral (Sp = 0.023, σg = 135 m) than in core (Sp = 0.014, σg = 109 m) populations. However, the mean neighborhood size was higher in the core (Nb = 82) than in the peripheral (Nb = 48) populations. Conclusion Eastern white cedar populations have significant fine-scale genetic structure at short distances. Peripheral

  9. Long Term Variability of the Canary Current Upwelling System inferred from Fine Scale Analysis of Satellite-derived SST

    NASA Astrophysics Data System (ADS)

    Relvas, P.; Luis, J. M.; Silva, P. L.; Santos, A. M.

    2011-12-01

    SST trends were created upon the slopes of the linear fits applied to each pixel. They show a generalized warming of the entire region. However, alternate patches of significantly different warming rates are observed, ranging from large scale down to mesoscale sized features that corresponds to known oceanographic structures, like coastal upwelling features. Going deep into short spatial scales, the spatial heterogeneities of the ocean became evident, revealing the importance of the mesoscale in the response to the global warming. The detail in the warming variability obtained here results in a large extent from the fine scale analysis and the numerical processing carefully designed to avoid trend bias in the climatological studies. Kilpatrick, K., G. Podestá, and R. Evans (2001), Overview of the NOAA/NASA Pathfinder algorithm for sea surface temperature and associated match-up database, J. Geophys. Res., 106, 9179-919

  10. Control of oscillatory thermocapillary convection in microgravity

    NASA Technical Reports Server (NTRS)

    Neitzel, G. Paul

    1994-01-01