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480 results for “spatial structure”
Data from: Dispersal syndromes can impact ecosystem functioning in spatially structured freshwater populations
Dispersal can strongly influence ecological and evolutionary dynamics. Besides the direct contribution of dispersal to population dynamics, dispersers often differ in their phenotypic attributes from non-dispersers, which leads to dispersal syndromes. The consequences of such dispersal syndromes have been widely explored at the population and community level, however, to date, ecosystem-level effects remain unclear. Here, we examine whether dispersing and resident individuals of two different aquatic keystone invertebrate species have different contributions to detrital processing, a key function in freshwater ecosystems. Using experimental two-patch systems, we found no difference in leaf consumption rates with dispersal status of the common native species Gammarus fossarum. In Dikerogammarus villosus, however, a Ponto-Caspian species now expanding throughout Europe, dispersers consumed leaf litter at roughly three times the rate of non-dispersers. Furthermore, this put the contribution of dispersing D. villosus to leaf litter processing on par with native G. fossarum, after adjusting for differences in organismal size. Given that leaf litter decomposition is a key function in aquatic ecosystems, and the rapid species turnover in freshwater habitats with range expansions of non-native species, this finding suggests that dispersal syndromes may have important consequences for ecosystem functioning.
Data from: Spatial population genetic structure of a bacterial parasite in close coevolution with its host
Knowledge of a species' population genetic structure can provide insight into fundamental ecological and evolutionary processes including gene flow, genetic drift, and adaptive evolution. Such inference is of particular importance for parasites, as an understanding of their population structure can illuminate epidemiological and coevolutionary dynamics. Here we describe the population genetic structure of the bacterium Pasteuria ramosa, a parasite that infects planktonic crustaceans of the genus Daphnia. This system has become a model for investigations of host-parasite interactions and represents an example of coevolution via negative frequency-dependent selection (a.k.a. 'Red Queen' dynamics). To sample P. ramosa, we experimentally infected a panel of Daphnia hosts with natural spore banks from the sediments of 25 ponds throughout much of the species range in Europe and Western Asia. Using 12 polymorphic VNTR loci, we identified substantial genetic diversity both within and among localities that was structured geographically among ponds. Genetic diversity was also structured among host genotypes within ponds, though this pattern varied by locality, with P. ramosa at some localities partitioned into distinct host-specific lineages, and other localities where recombination had shuffled genetic variation among different infection phenotypes. Across the sample range, there was a pattern of isolation-by-distance, and principal components analysis coupled with Procrustes rotation identified congruence between patterns of genetic variation and geography. Our findings support the hypothesis that Pasteuria is an endemic parasite coevolving closely with its host. These results provide important context for previous studies of this model system and inform hypotheses for future research.
Data from: The effect of sex-biased dispersal on opposite-sexed spatial genetic structure and inbreeding risk
Natal sex-biased dispersal has long been thought to reduce the risk of inbreeding by spatially separating opposite-sexed kin. Yet, comprehensive and quantitative evaluations of this hypothesis are lacking. In this study, we quantified the effectiveness of sex-biased dispersal as an inbreeding avoidance strategy by combining spatially explicit simulations and empirical data. We quantified the extent of kin clustering by measuring the degree of spatial autocorrelation among opposite-sexed individuals (FM structure). This allowed us to systematically explore how the extent of sex-biased dispersal, generational overlap, and mate searching distance, influenced both kin clustering, and the resulting inbreeding in the absence of complementary inbreeding avoidance strategies. Simulations revealed that when sex-biased dispersal was limited, positive FM genetic structure developed quickly and increased as the mate searching distance decreased or as generational overlap increased. Interestingly, complete long-range sex-biased dispersal did not prevent the development of FM genetic structure when generations overlapped. We found a very strong correlation between FM genetic structure and both FIS under random mating, and pedigree-based measures of inbreeding. Thus, we show that the detection of FM genetic structure can be a strong indicator of inbreeding risk. Empirical data for two species with different life history strategies yielded patterns congruent with our simulations. Our study illustrates a new application of spatial genetic autocorrelation analysis that offers a framework for quantifying the risk of inbreeding that is easily extendable to other species. Furthermore, our findings provide other researchers with a context for interpreting observed patterns of opposite-sexed spatial genetic structure.
Data from: Effects of fire regime on the population genetics of natural pine stands, in Genetic structure of forest trees in biodiversity hotspots at different spatial scales (Ph.D. thesis).
The recurrence of wildfires is predicted to increase worldwide due to climate change, resulting in severe impacts on biodiversity and ecosystem functioning. We used simple sequence repeat (SSR) and single nucleotide polymorphism (SNP) markers to examine the effects of fire regime on genetic diversity, demographic history and fine-scale spatial genetic structure (SGS) of Pinus pinaster and P. halepensis, two conifers with similar adaptations to fire in the eastern Iberian Peninsula. Stands growing under high (HiFi) or low (LoFi) frequency of crown fires had similar levels of genetic diversity and similar demographic history, with bottlenecks detected in all stands in both species. HiFi populations were not genetically depleted, suggesting that adaptations such as a diverse canopy seed bank due to serotinous cones, an early age of first flowering and high gene flow buffer against possible reductions of genetic diversity. Significantly stronger SGS at SNPs in HiFi than LoFi stands of P. halepensis suggested fire-related altered dispersal possibly combined with microenvironmental selection in this fire-sensitive "seeder" species. In contrast, SGS at SNP markers was unrelated to fire regime in P. pinaster. This could be a consequence of more pronounced fire-resistance in this species enabling some adults to survive fire, hence causing a lower dependence on post-fire regeneration. Our results highlight that the impact of fire differs in species with similar life-history traits. Therefore, species-specific studies are needed to understand the role of wildfires for the evolution of future forests
Data from: The relative influence of habitat amount and configuration on genetic structure across multiple spatial scales
Despite strong interest in understanding how habitat spatial structure shapes the genetics of populations, the relative importance of habitat amount and configuration for patterns of genetic differentiation remains largely unexplored in empirical systems. In this study, we evaluate the relative influence of, and interactions among, the amount of habitat and aspects of its spatial configuration on genetic differentiation in the pitcher plant midge, Metriocnemus knabi. Larvae of this species are found exclusively within the water-filled leaves of pitcher plants (Sarracenia purpurea) in a system that is naturally patchy at multiple spatial scales (i.e., leaf, plant, cluster, peatland). Using generalized linear mixed models and multimodel inference, we estimated effects of the amount of habitat, patch size, interpatch distance, and patch isolation, measured at different spatial scales, on genetic differentiation (FST) among larval samples from leaves within plants, plants within clusters, and clusters within peatlands. Among leaves and plants, genetic differentiation appears to be driven by female oviposition behaviors and is influenced by habitat isolation at a broad (peatland) scale. Among clusters, gene flow is spatially restricted and aspects of both the amount of habitat and configuration at the focal scale are important, as is their interaction. Our results suggest that both habitat amount and configuration can be important determinants of genetic structure and that their relative influence is scale dependent.
Data from: Clone configuration and spatial genetic structure of two Halophila ovalis populations with contrasting internode lengths
Fine-scale spatial genetic structure (SGS) is predominantly determined by gene flow. While sexually reproducing plants can disperse their genes through pollen and seed grains, clonal plants can additionally disperse genes through clonal growth. Plants' clonal reproduction strategy, however, often varies within and between species. Still, the effect of differential clonal reproduction strategy on fine-scale SGS remains somewhat unclear. Halophila ovalis is a fast-growing clonal seagrass, whose internode length (which defines a species' clonal reproduction strategy) varies among populations. Using eight polymorphic microsatellites, here we compare the genetic diversity, clonal structure and fine-scale SGS of two H. ovalis populations with contrasting internode lengths (Yingluo versus Xialongwei populations). We found moderate to high genotypic and allelic richness and heterozygosities in both populations. Compared to Xialongwei population, genetic and genotypic diversity was significantly lower in Yingluo population. Although their internode length was relatively short, clones of Yingluo population spread farther than those of Xialongwei population. Sexual-to-vegetative dispersal variance ratios were 34.6 and 445.5 in Yingluo and Xialongwei populations, respectively. In both populations, clonal growth significantly intensified the SGS, especially in short distance classes. The SGS at small distance classes were weaker in Yingluo than Xialongwei, in part, due to more intermingled distribution of genets and more extensive clonal expansion in the former population. Our results indicate that vegetative dispersal variance/distance, rather than internode length, plays a crucial role in shaping the fine-scale genetic structure.
Data from: Sex-biased dispersal creates spatial genetic structure in a parthenogenetic ant with a dependent-lineage reproductive system
Reproduction and dispersal are key aspects of species life history that influence spatial genetic structure in populations. Several ant species in the genus Cataglyphis have evolved a unique breeding system in which new reproductives (that is, queens and males) are produced asexually by parthenogenesis; in contrast, non-reproductives (that is, workers) are produced via sexual reproduction by mates from distinct genetic lineages. We investigated how these two coexisting reproductive methods affect population-level spatial genetic structure using the ant Cataglyphis mauritanica as a model. We obtained genotypes for queens and their male mates from 338 colonies, and we found that the two lineages present in the study population occurred with equal frequency. Furthermore, analysis of spatial genetic structure revealed strong sex-biased dispersal. Because queens were produced by parthenogenesis and because they dispersed over short distances, there was an extreme level of spatial structuring: a mosaic of patches composed of clonal queens was formed. Males, on the other hand, dispersed over several hundred metres and, thus, across patches, ensuring successful interlineage mating.
Data from: Spatial heterogeneity in landscape structure influences dispersal and genetic structure: empirical evidence from a grasshopper in an agricultural landscape
Dispersal may be strongly influenced by landscape and habitat characteristics that could either enhance or restrict movements of organisms. Therefore, spatial heterogeneity in landscape structure could influence gene flow and the spatial structure of populations. In the past decades, agricultural intensification has led to the reduction in grassland surfaces, their fragmentation and intensification. As these changes are not homogeneously distributed in landscapes, they have resulted in spatial heterogeneity with generally less intensified hedged farmland areas remaining alongside streams and rivers. In this study, we assessed spatial pattern of abundance and population genetic structure of a flightless grasshopper species, Pezotettix giornae, based on the surveys of 363 grasslands in a 430-km² agricultural landscape of western France. Data were analysed using geostatistics and landscape genetics based on microsatellites markers and computer simulations. Results suggested that small-scale intense dispersal allows this species to survive in intensive agricultural landscapes. A complex spatial genetic structure related to landscape and habitat characteristics was also detected. Two P. giornae genetic clusters bisected by a linear hedged farmland were inferred from clustering analyses. This linear hedged farmland was characterized by high hedgerow and grassland density as well as higher grassland temporal stability that were suspected to slow down dispersal. Computer simulations demonstrated that a linear-shaped landscape feature limiting dispersal could be detected as a barrier to gene flow and generate the observed genetic pattern. This study illustrates the relevance of using computer simulations to test hypotheses in landscape genetics studies.
Increased spatial-genetic structure in a population of the clonal aquatic plant Sagittaria latifolia (Alismataceae) following disturbance
<p>The spatial genetic structure (SGS) of plant populations is determined by the outcome of key ecological processes, including pollen and seed dispersal, the intensity of local resource competition among newly recruited plants, and patterns of mortality among established plants. Changes in the magnitude of SGS over time can provide insights into the operation of these processes. We measured SGS in a population of the clonal aquatic plant, <i>Sagittaria latifolia</i> that had been disturbed by flooding, both before and after the flood. . Over the four-year interval between measurements, we found substantial changes in the magnitude of SGS. In the first measurement (pre-flood), SGS was weak, even over short distances. By contrast, there was substantial SGS in the second measurement (post-flood), particularly over short distances. This change in SGS was accompanied by near complete turnover in the genotypic composition of the population. The genotypic richness of the population (the number of unique clones scaled by the sample size) was halved over the four-year interval. The clonal subrange – the distances between shoots within clones – also shrank considerably, with more than 5% of shoots having clone-mates at distances greater than 10 m before the flood, but fewer than 5% of shoots having clone-mates at distances beyond 2 m afterwards. Clonal turnover and the re-establishment of SGS in clonal populations are both expected following local extirpation and recruitment. These data reveal the genetic signatures of disturbance and a subsequent flush of seedling recruitment and subsequent clonal expansion.</p>
Figure 3 in Diverging structures, perch heights, temperatures, and levels of sunlight of spatial niche dimensions ease the syntopic life of Tropidurus hispidus and Tropidurus semitaeniatus (Squamata: Tropiduridae)
Figure 3. Correlations of distance from the nearest potential shelter (cm) with (a) snout-vent length (mm) and (b) body mass (g) of Tropidurus semitaeniatus. The straight and the curved lines represent, respectively, linear and quadratic models.
Figure 1 in Diverging structures, perch heights, temperatures, and levels of sunlight of spatial niche dimensions ease the syntopic life of Tropidurus hispidus and Tropidurus semitaeniatus (Squamata: Tropiduridae)
Figure 1. Ordination by non-metric multidimensional scaling comparing proportions of leaf litter, sand, vegetation, and rock between (a) Tropidurus semitaeniatus (×) and environmental availability (∆) (stress = 0.1534), and (b) Tropidurus hispidus (○) and environmental availability (∆) (stress = 0.0877). Proximity and distance between points indicates, respectively, similarity or dissimilarity.
Figure 4 in Diverging structures, perch heights, temperatures, and levels of sunlight of spatial niche dimensions ease the syntopic life of Tropidurus hispidus and Tropidurus semitaeniatus (Squamata: Tropiduridae)
Figure 4. Differences in distances from nearest potential shelters (cm, log) among types of shelter for Tropidurus semitaeniatus. The mean distance was longer from vegetation than from rock shelters. Upwards, the horizontal lines of the boxplots represent the minimum range, first quartile, median, third quartile, and maximum range. The unit of the original measurement scale is presented for the logarithmic values of the vertical axis.
Figure 2 in Diverging structures, perch heights, temperatures, and levels of sunlight of spatial niche dimensions ease the syntopic life of Tropidurus hispidus and Tropidurus semitaeniatus (Squamata: Tropiduridae)
Figure 2. Ordination by non-metric multidimensional scaling comparing proportions of shade, filtered sunlight, and full sunlight, air temperatures and substrate temperatures between (a) Tropidurus hispidus (○) and T. semitaeniatus (×) (stress = 0.1785), (b) T. hispidus (○) and environmental availability (∆) (stress = 0.1004), and (C) T. semitaeniatus (×) and that available in the environment (∆) (stress = 0.2534). Proximity and distance between points indicates, respectively, similarity or dissimilarity.
Figure 5 in Diverging structures, perch heights, temperatures, and levels of sunlight of spatial niche dimensions ease the syntopic life of Tropidurus hispidus and Tropidurus semitaeniatus (Squamata: Tropiduridae)
Figure 5. Frequency distribution (horizontal axis; in %) of perch heights (vertical axes; in cm) used by Tropidurus hispidus and Tropidurus semitaeniatus.
The relative influence of history, climate, topography and vegetation structure on local animal richness varies among taxa and spatial grains
<p>Understanding the spatial scales at which environmental factors drive species richness patterns is a major challenge in ecology. Due to the trade-off between spatial grain and extent, studies tend to focus on a single spatial scale, and the effects of multiple environmental variables operating across spatial scales on the pattern of local species richness have rarely been investigated.</p> <p>Here, we related variation in local species richness of ground beetles, landbirds, and small mammals to variation in vegetation structure and topography, regional climate, biome diversity, and glaciation history for 27 sites across the USA at two different spatial grains.</p> <p>We studied the relative influence of broad-scale (landscape) environmental conditions using variables estimated at the site level (climate, productivity, biome diversity, and glacial era ice cover) and fine-scale (local) environmental conditions using variables estimated at the plot level (topography and vegetation structure) to explain local species richness. We also examined whether plot-level factors scale up to drive continental scale richness patterns. We used Bayesian hierarchical models and quantified the amount of variance in observed richness that was explained by environmental factors at different spatial scales.</p> <p>For all three animal groups, our models explained much of the variation in local species richness (85-89%), but site-level variables explained a greater proportion of richness variance than plot-level variables. Temperature was the most important site-level predictor for explaining variance in landbirds and ground beetles richness. Some aspects of vegetation structure were the main plot-level predictors of landbird richness. Environmental predictors generally had poor explanatory power for small mammal richness, while glacial era ice cover was the most important site-level predictor.</p> <p>Relationships between plot-level factors and richness varied greatly among geographical regions and spatial grains, and most relationships did not hold when predictors were scaled up to continental scale. Our results suggest that the factors that determine richness may be highly dependent on spatial grain, geography, and animal group. We demonstrate that instead of artificially manipulating the resolution to study multi-scale effects, a hierarchical approach that uses fine grain data at broad extents could help solve the issue of scale selection in environment-richness studies. </p>
Spatiotemporal connectivity dynamics in spatially structured populations
<p>Connectivity is a fundamental concept linking dispersal to the emergent dynamics and persistence of spatially structured populations. Functional measures of connectivity typically seek to integrate aspects of landscape structure and animal movement to describe ecologically meaningful connectedness at the landscape and population scale.</p> <p>Despite this focus on function, traditional measures of landscape connectivity assume it is a static property of the landscape, hence abstracting out the underlying spatiotemporal population dynamics. Connectivity is, arguably, a dynamic property of landscapes, and is inherently related to the spatial distribution of individuals and populations across the landscape. Static representations of connectivity potentially overlook this variation and therefore adopting a dynamic approach should offer improved insights about connectivity and associated ecological processes.</p> <p>Using a large scale, long-term time-series of occupancy data from a metapopulation of water voles (Arvicola amphibius), we tested competing hypotheses about how considering the dynamic nature of connectivity improves the ability of spatially-explicit occupancy models to recover population dynamics. Iteratively relaxing standing assumptions of connectivity metrics, these models ranged from spatially and temporally fixed connectivity metrics that are widely applied, to the more flexible, but lesser used model that allowed temporally-varying connectivity measures that incorporate spatiotemporally dynamic patch occupancy states.</p> <p>Our results provide empirical evidence that demographic-weighting using patch occupancy dynamics and temporal variability in connectivity measures are important for describing metapopulation dynamics.</p> <p>We highlight the implications of commonly held assumption in connectivity modeling and demonstrate how they result in different and highly variable predictions of metapopulation capacity. Thus, we argue that the concept of connectivity and its potential applications would benefit from recognizing inherent spatiotemporal variation in connectivity that is explicitly linked to underlying ecological state variables. </p>
Supplementary material 1 from: Nedkov S, Zhiyanski M, Dimitrov S, Borisova B, Popov A, Ihtimanski I, Yaneva R, Nikolov P, Bratanova-Doncheva S (2017) Mapping and assessment of urban ecosystem condition and services using integrated index of spatial structure. One Ecosystem 2: e14499. https://doi.org/10.3897/oneeco.2.e14499
Figure representing examples of catalogues used during the identification built and land cover types.
Supplementary material 2 from: Nedkov S, Zhiyanski M, Dimitrov S, Borisova B, Popov A, Ihtimanski I, Yaneva R, Nikolov P, Bratanova-Doncheva S (2017) Mapping and assessment of urban ecosystem condition and services using integrated index of spatial structure. One Ecosystem 2: e14499. https://doi.org/10.3897/oneeco.2.e14499
Table representing all combinations of the integrated index of spatial structute in urban ecosystems in Bulgaria
FIG. 4 in Nest-Site Fidelity and Sex-Biased Dispersal Affect Spatial Genetic Structure of Eastern Box Turtles (Terrapene carolina carolina) at Their Northern Range Edge
FIG. 4. Analysis of global structure along the river corridor from the first principal component of the sPCA represented by (A) interpolation of lagged principal scores showing genetic clines and (B) colors indicating individual scores. Coordinates have been deliberately omitted to deter poachers.
FIG. 3 in Nest-Site Fidelity and Sex-Biased Dispersal Affect Spatial Genetic Structure of Eastern Box Turtles (Terrapene carolina carolina) at Their Northern Range Edge
FIG. 3. Bubble plot showing the results of two-dimensional local spatial autocorrelation analysis for all Eastern Box Turtles (n ¼ 165) sampled in northwestern Michigan. Circles represent individuals and the size of the circle is proportional to the P-values from permutation testing, with large circles representing individuals that are significantly more related to their five nearest neighbors than expected (P, 0.05) based on a random distribution of genotypes. Figure shows the distribution of five genetic ''hotspots'' in relation to known nesting sites (NS) across the study area. Some distantly sampled individuals are omitted for figure clarity.
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These curated guides explain access requirements, typical timelines, costs, and reuse considerations for widely used research datasets.
Allen Brain Atlas
Allen Brain Atlas is an Allen Institute collection of brain map atlases, datasets, APIs, and analysis tools covering mouse, human, and non-human primate brain resources.
Annotated Behaviour and Observability Dataset (ABODe)
ABODe is a University of Edinburgh DataShare dataset for behavior classification in group-housed mice using home-cage video, identities, bounding boxes, ground-plate positions, and annotator labels.
DANDI Archive for NWB datasets
DANDI is a BRAIN Initiative archive for publishing and sharing neurophysiology data, including electrophysiology, optophysiology, and behavioral data packaged as NWB and related standards.
International Brain Laboratory public data
The International Brain Laboratory public data releases expose standardized mouse decision-making experiments, including Neuropixels recordings, widefield calcium imaging, behavior, and session metadata accessed through the ONE API.
OpenNeuro
OpenNeuro is a free, open platform for sharing neuroimaging datasets, with public search, dataset pages, and download paths for web, S3, DataLad, and the OpenNeuro CLI.