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1,659 results for “structured population”
Azole resistance mechanisms and population structure of Aspergillus fumigatus on retail plant products
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Population structure and genetic differentiation in extant alligator snapping turtles (genus Macrochelys) with implications for taxonomy and conservation
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Data from: Geographic structuring of Antarctic penguin populations
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Supplementary material 1 from: Grabowska J, Kvach Yu, Rewicz T, Pupins M, Kutsokon I, Dykyy I, Antal L, Zięba G, Rakauskas V, Trichkova T, Čeirāns A, Grabowski M (2020) First insights into the molecular population structure and origins of the invasive Chinese sleeper, Perccottus glenii, in Europe. NeoBiota 57: 87-107. https://doi.org/10.3897/neobiota.57.48958
Table S1. Table presents Chinese sleeper haplotypes frequency (belonging to three distinguished groups) found in studies sites.
Population genetic structure and demographic history of the lone star tick, Amblyomma americanum (Ixodida: Ixodidae): new evidence supporting old records
Range expansions are a potential outcome of climate change. Population genetic structure and demography can be used as tools to evaluate hypotheses on changes in geographic distribution. In this study we explored the genetic variability, population genetic structure, demographic history, and habitat suitability of Amblyomma americanum, a North American tick species that is a known vector of several pathogenic microorganisms. We used a novel double digestion restriction site-associated DNA sequencing (dd-RAD seq), and we discovered 8181 independent single nucleotide polymorphisms (SNPs) from 189 ticks from across the geographic range of the species. Overall, genetic diversity was lower than expected. Further, the edge populations did not have a statistically significant lower diversity than core populations, and hypotheses of range expansion are not supported by a test based on genetic data. Nonetheless, moderate levels of population structure were detected among geographic regions, with the northeast cluster the least variable. Demographic and species distribution models support a scenario where A. americanum was present in more northern locations in the past, underwent a bottleneck, and is now recovering. These findings highlight the importance of demographic modeling and genomic data in assessing the recent history and genetic structure of pathogen vectors.
Data from: The geographic mosaic of arms race coevolution is closely matched to prey population structure
<p>Reciprocal adaptation is the hallmark of arms race coevolution. Local coadaptation between natural enemies should generate a geographic mosaic pattern where both species have roughly matched abilities across their shared range. However, mosaic variation in ecologically relevant traits can also arise from processes unrelated to reciprocal selection, such as population structure or local environmental conditions. We tested whether these alternative processes can account for trait variation in the geographic mosaic of arms race coevolution between resistant garter snakes (<i>Thamnophis sirtalis</i>) and toxic newts (<i>Taricha granulosa</i>). We found that predator resistance and prey toxin levels are functionally matched in co-occurring populations, suggesting that mosaic variation in the armaments of both species results from the local pressures of reciprocal selection. By the same token, phenotypic and genetic variation in snake resistance deviates from neutral expectations of population genetic differentiation, showing a clear signature of adaptation to local toxin levels in newts. Contrastingly, newt toxin levels are best predicted by genetic differentiation among newt populations, and to a lesser extent, by the local environment and snake resistance. Exaggerated armaments suggest that coevolution occurs in certain hotspots, but prey population structure seems to be of particular influence on local phenotypic variation in both species throughout the geographic mosaic. Our results imply that processes other than reciprocal selection, like historical biogeography and environmental pressures, represent an important source of variation in the geographic mosaic of coevolution. Such a pattern supports the role of "trait remixing" in the geographic mosaic theory, the process by which non-adaptive forces dictate spatial variation in the interactions among species.</p>
Data from: eDNA concentration, population size structure, and mark-recapture data
<p>Organism abundance is a critical parameter in ecology, but its estimation is often challenging. Approaches utilizing eDNA to indirectly estimate abundance have recently generated substantial interest. However, preliminary correlations observed between eDNA concentration and abundance in nature are typically moderate in strength with significant unexplained variation. Here we apply a novel approach to integrate allometric scaling coefficients into models of eDNA concentration and organism abundance. We hypothesize that eDNA particle production scales non-linearly with mass, with scaling coefficients < 1. Wild populations often exhibit substantial variation in individual body size distributions; we therefore predict that the distribution of mass across individuals within a population will influence population-level eDNA production rates. To test our hypothesis, we collected standardized body size distribution and mark-recapture abundance data using whole-lake experiments involving nine populations of brook trout. We correlated eDNA concentration with three metrics of abundance: density (individuals/ha), biomass (kg/ha), and allometrically scaled mass (ASM) (∑(individual mass<sup>0.73</sup>)/ha). Density and biomass were both significantly positively correlated with eDNA concentration (adj. r<sup>2</sup> = 0.59 and 0.63, respectively), but ASM exhibited improved model fit (adj. r<sup>2</sup> = 0.78). We also demonstrate how estimates of ASM derived from eDNA samples in 'unknown' systems can be converted to biomass or density estimates with additional size structure data. Future experiments should empirically validate allometric scaling coefficients for eDNA production, particularly where substantial intraspecific size distribution variation exists. Incorporating allometric scaling may improve predictive models to the extent that eDNA concentration may become a reliable indicator of abundance in nature.</p>
Data from: Temporal variation in spatial genetic structure during population outbreaks: distinguishing among different potential drivers of spatial synchrony
Spatial synchrony is a common characteristic of spatio-temporal population dynamics across many taxa. While it is known that both dispersal and spatially autocorrelated environmental variation (i.e., the Moran effect) can synchronize populations, the relative contributions of each, and how they interact, is generally unknown. Distinguishing these mechanisms and their effects on synchrony can help us to better understand spatial population dynamics, design conservation and management strategies, and predict climate change impacts. Population genetic data can be used to tease apart these two processes as the spatio-temporal genetic patterns they create are expected to be different. A challenge, however, is that genetic data are often collected at a single point in time, which may introduce context-specific bias. Spatio-temporal sampling strategies can be used to reduce bias and to improve our characterization of the drivers of spatial synchrony. Using spatio-temporal analyses of genotypic data, our objective was to identify the relative support for these two mechanisms to the spatial synchrony in population dynamics of the irruptive forest insect pest, the spruce budworm (Choristoneura fumiferana), in Quebec (Canada). AMOVA, cluster analysis, isolation by distance and sPCA were used to characterize spatio-temporal genomic variation using 1370 SBW larvae sampled over four years (2012-2015) and genotyped at 3,562 SNP loci. We found evidence of overall weak spatial genetic structure that decreased from 2012 to 2015 and a genetic diversity homogenization among the sites. We also found genetic evidence of a long-distance dispersal event over > 140 km. These results indicate that dispersal is the key mechanism involved in driving population synchrony of the outbreak. Early intervention management strategies that aim to control source populations have the potential to be effective through limiting dispersal. However, the timing of such interventions relative to outbreak progression is likely to influence their probability of success.
Data from: Genetic population structure and variation at phenology-related loci in anadromous Arctic char (Salvelinus alpinus)
The Arctic will be especially affected by climate change, resulting in altered seasonal timing. Anadromous Arctic char (Salvelinus alpinus) is strongly influenced by sea surface temperature (SST) delimiting time periods available for foraging in the sea. Recent studies of salmonid species have shown variation at phenology-related loci associated with timing of migration and spawning. We contrasted genetic population structure at 53 SNPs versus four phenology-related loci among 15 anadromous Arctic char populations from Western Greenland and three outgroup populations. Among anadromous populations, the time period available for foraging at sea (> 2oC) ranges from a few weeks to several months, motivating two research questions: 1) Is population structure compatible with possibilities for evolutionary rescue of anadromous populations during climate change? 2) Does selection associated with latitude or SST regimes act on phenology-related loci? In Western Greenland, strong isolation-by-distance at SNPs was observed and spatial autocorrelation analysis showed genetic patch size up to 450 km, documenting contingency and gene flow among populations. Outlier tests provided no evidence for selection at phenology-related loci. However, in Western Greenland, mean allele length at OtsClock1b was positively associated with the time of year when SST first exceeded 2oC and negatively associated with duration of the period where SST exceeded 2oC. This is consistent with local adaptation for making full use of the time period available for foraging in the sea. Current adaptation may become maladaptive under climate change, but long-distance connectivity of anadromous populations could redistribute adaptive variation across populations and lead to evolutionary rescue.
Data from: Environmental variables associated with Nothophaeocryptopus gaeumannii population structure and Swiss needle cast severity in Western Oregon and Washington
The environment has a strong influence on the abundance and distribution of plant pathogenic organisms, and plays a major role in the causation of plant disease. Climatological factors may also alter the dynamics of the interactions between plant pathogens and their hosts. Nothophaeocryptopus (=Phaeocryptopus) gaeumannii, the causal agent of Swiss needle cast (SNC) of Douglas-fir, is endemic to western North America where it exists as two sympatric, reproductively isolated lineages. The abundance of this fungus and the severity of SNC are strongly influenced by climate. We used statistical and population genetic analyses to examine relationships between environment, pathogen population structure, and SNC severity. Although N. gaeumannii Lineage 2 in western Oregon and Washington was most abundant where SNC symptoms were most severe, we did not detect a significant relationship between Lineage 2 and disease severity. Warmer winter temperatures were inversely correlated with foliage retention (AFR) and positively correlated with the relative abundance of Lineage 2 (PL2). However when distance inland, which was strongly correlated with both AFR and PL2, was included in the model, there was no significant relationship between Lineage 2 and AFR. Spring/early summer dew point temperatures also were positively associated with total N. gaeumannii abundance (colonization index (CI)), and inversely correlated with AFR. Warmer summer mean temperatures were associated with lower CI and higher AFR. Our results suggest that the two lineages have overlapping environmental optima, but slightly different tolerance ranges. Lineage 2 was absent from more inland sites where winters are colder and summers are warm and dry, while Lineage 1 occurred at most sites across an environmental gradient suggesting broader environmental tolerance. These relationships suggest that climate influences the abundance and distribution of this ecologically important plant pathogen, and may have played a role in the evolutionary divergence of these two cryptic fungal lineages.
Data from: Genotyping-in-Thousands by sequencing reveals marked population structure in Western Rattlesnakes to inform conservation status
<p>Delineation of units below the species level is critical for prioritizing conservation actions for species at-risk. Genetic studies play an important role in characterizing patterns of population connectivity and diversity to inform the designation of conservation units, especially for populations that are geographically isolated. The northernmost range margin of Western Rattlesnakes (<em>Crotalus oreganus</em>) occurs in British Columbia, Canada, where it is federally classified as threatened and restricted to five geographic regions. In these areas, Western Rattlesnakes hibernate (den) communally, raising questions about connectivity within and between den complexes. At present, Western Rattlesnake conservation efforts are hindered by a complete lack of information on genetic structure and degree of isolation at multiple scales, from the den to the regional level. To fill this knowledge gap, we used Genotyping-in-Thousands by sequencing (GT-seq) to genotype an optimized panel of 362 single nucleotide polymorphisms (SNPs) from individual samples (n = 461) collected across the snake's distribution in western Canada and neighboring Washington (USA). Hierarchical STRUCTURE analyses found evidence for population structure within and among the five geographic regions in BC, as well as in Washington. Within these regions, 11 genetically distinct complexes of dens were identified, with some regions having multiple complexes. No significant pattern of isolation-by-distance and generally low levels of migration were detected among den complexes across regions. Additionally, snakes within dens generally were more related than those among den complexes within a region, indicating limited movement. Overall, our results suggest that the single, recognized designatable unit for Western Rattlesnakes in Canada should be re-assessed to proactively focus conservation efforts on preserving total genetic variation detected range wide. More broadly, our study demonstrates a novel application of GT-seq for investigating patterns of diversity in wild populations at multiple scales to better inform conservation management.</p>
Genetic connectivity and population structure of African savanna elephants (Loxodonta africana) in Tanzania
<p>Increasing human population growth, exurban development, and associated habitat fragmentation is accelerating the isolation of many natural areas and wildlife populations across the planet. In Tanzania, rapid and ongoing habitat conversion to agriculture has severed many of the country's former wildlife corridors between protected areas. To identify historically-linked protected areas, we investigated the genetic structure and gene flow of African savanna elephants in Tanzania using microsatellite and mitochondrial DNA markers in 688 individuals. Our results indicate distinct population genetic structure within and between ecosystems across Tanzania, and reveal important priority areas for connectivity conservation. Elephants sampled from the Tarangire-Manyara ecosystem appear marginally, yet significantly isolated from elephants sampled from the greater Serengeti ecosystem (mean FST = 0.03), where two distinct subpopulations were identified.Unexpectedly, elephants in the Lake Manyara region appear to be more closely related to those across the East African Rift wall in the Ngorongoro Conservation Area than they are to the neighboring Tarangire subpopulations. We concluded that the Rift wall has had a negligible influence on genetic differentiation up to this point, but differentiation may accelerate in the future because of ongoing loss of corridors in the area. Interestingly, relatively high genetic similarity was found between elephants in Tarangire and Ruaha although they are separated by >400 km. In southern Tanzania, there was little evidence of female-mediated gene flow between Ruaha and Selous, probably due to the presence of the Udzungwa Mountains between them. Despite observing evidence of significant isolation, the populations of elephants we examined generally exhibited robust levels of allelic richness (mean AR = 9.96), heterozygosity (mean µHE = 0.73), and effective population sizes (mean Ne = 148). Our results may inform efforts to restore wildlife corridors between protected areas in Tanzania in order to facilitate gene flow for long-term survival of elephants and other species.</p>
Data from: Population genetic structures of two ecologically distinct species Betula platyphylla and B. ermanii inferred based on nuclear and chloroplast DNA markers
Climatic oscillations during the last glacial maximum (LGM) significantly affected the distribution patterns and genetic structure of extant plants. Northeast China (NEC) is a major biodiversity center in East Asia, and the influence of historical climate change on NEC populations is critical for understanding species responses to future climate change. However, only a few phylogeographic studies of cool-temperate deciduous tree species have been conducted in the area, and results are inconsistent for species with different niches or distribution areas. We employed multiple chloroplast and nuclear markers to investigate the genetic structure of two ecologically contrasting species, Betula platyphylla and B. ermanii, in NEC. Rare haplotypes were identified in the chloroplast genome of these species, and both exhibited high levels of nucleotide diversity based on a fragment of the nuclear gene G3PDH and microsatellites. Moreover, significant phylogeographic structure was detected for B. platyphylla, suggesting that these populations had recolonized from independent glacial refuges, whereas no genetic structure was found for B. ermanii.
High site fidelity does not equate to population structure for common goldeneye and Barrow's goldeneye in North America.
<p>Delineation of population structure provides valuable information for conservation and management of species, as levels of demographic and genetic connectivity not only affect population dynamics but also have important implications for adaptability and resiliency of populations and species. Here, we measure population genetic structure and connectivity across the respective ranges of two sister species of Goldeneye, Barrow's Goldeneye (<i>Bucephala islandica</i>) and Common Goldeneye (<i>B. clangula</i>). We use two different marker types: 7 nuclear microsatellite loci assayed across 229 samples and 3,678 double digest Restriction-site Associated DNA Sequencing (ddRAD-seq) loci assayed across 61 samples. First, both datasets failed to uncover genetic structure within Common or Barrow's Goldeneye, including between North American and European samples of Common Goldeneye. These results are in contrast with previous mitochondrial DNA, band recovery, and telemetry data which suggests that goldeneyes are structured across their range. We posit that the discordance between autosomal genetic markers and other data types suggests that males, possibly subadult males, may be maintaining genetic connectivity across each species' respective ranges. Next, although inter-specific brood parasitism was expected to cause some level of gene flow, we only identified a single F1 hybrid with no further evidence of contemporary or historical gene flow. Despite ddRAD-seq demographic analyses which recovered an optimum evolutionary model of split with migration (i.e., secondary contact), estimates of gene flow were <<1 migrant per generation in both directions. Together, we conclude that either strong ecological barriers or assortative mating are likely playing a role in preventing further backcrossing. Finally, demographic analyses estimated a relatively deep divergence time between Barrow's Goldeneye and Common Goldeneye of ~1.6 million years before present and that the genomes of both species have been under similar evolutionary constraints.</p>
Major inconsistencies of inferred population genetic structure estimated in a large set of domestic horse breeds using microsatellites
<p>STRUCTURE remains the most applied tool aimed at recovering the true, but unknown, population structure from observed microsatellite data or other genetic markers. About 30% of <span class="Program"><span>STRUCTURE</span></span>-based studies could not be reproduced (Gilbert et al., 2012). Here we use a large set of data from 2323 horses from 93 domestic breeds plus the Przewalski horse, typed at 15 microsatellite markers, to evaluate how program settings, in particular the so far insufficiently evaluated number of replicates, impact the estimation of the optimal number of population clusters <i>K</i><sub>opt</sub> that best describe the observed data. Domestic horses are suited as a test case as there is extensive knowledge of the history of many breeds, extensive phylogenetic analyses. Different methods based on different genetic assumptions and statistical procedures (<span class="Program"><span>DAPC</span></span>, <span class="Program"><span>FLOCK</span></span>, PCoA and <span class="Program"><span>STRUCTURE</span></span> with different run scenarios) all revealed the general, broad-scale relationships among the breeds that largely reflect known breed histories but diverged largely how they characterized small-scale patterns. <span class="Program"><span>STRUCTURE</span></span> failed to consistently identify <i>K</i><sub>opt</sub> using the most widespread approach, the ΔK method, despite very large numbers of MCMCs (3,000,000) and replicates (100). The interpretation of breed structure over increasing numbers of<i> K</i>, without assuming a <i>K</i><sub>opt</sub>, was consistent with known breed histories. The over-reliance on <i>K</i><sub>opt</sub> should be replaced by a qualitative description of clustering over increasing <i>K</i>, which is scientifically more honest and has the advantage of being much faster and less computer intensive as lower numbers of MCMC iterations and repetitions suffice for stable results. Very large data sets are highly challenging for cluster analyses, especially when populations with complex genetic histories are investigated.</p>
Extended Data: Population structure of Salmonella serotype Mbandaka
<p>This project contains supplementary figures associated with the project.</p>
Predator population size structure alters consumption of prey from epigeic and grazing food webs
<p>Numerous studies have found that predators can suppress prey densities and thereby impact important ecosystem processes such as plant productivity and decomposition. However, prey suppression by spiders can be highly variable. Unlike predators that feed on prey within a single energy channel, spiders often consume prey from asynchronous energy channels, such as grazing (live plant) and epigeic (soil surface) channels. Spiders undergo few life cycle changes and thus appear to be ideally suited to link energy channels, but ontogenetic diet shifts in spiders have received little attention. For example, spider use of different food channels may be highly specialized in different life stages and thus a species may be a multichannel omnivore only when we consider all life stages. Using stable isotopes, we investigated whether wolf spider (Pardosa littoralis, henceforth Pardosa) prey consumption is driven by changes in spider size. Small spiders obtained > 80% of their prey from the epigeic channel, whereas larger spiders used grazing and epigeic prey almost equally. Changes in prey consumption were not driven by changes in prey density, but by changes in prey use by different spider size classes. Thus, because the population size structure of Pardosa changes dramatically over the growing season, changes in spider size may have important implications for the strength of trophic cascades. Our research demonstrates that life history can be an important component of predator diet, which may in turn affect community- and ecosystem-level processes.</p>
Identity-by-descent detection across 487,409 British samples reveals fine scale population structure and ultra-rare variant associations: data related to publication
<p>Data related to the following publication:</p> <p>"Identity-by-descent detection across 487,409 British samples reveals fine scale population structure and ultra-rare variant associations"</p>
Data from: Contrasting patterns of population structure at large and fine scales in an avian disturbance specialist of braided river ecosystems
Aim: To understand the population structure and its potential drivers at different spatial scales in a migratory bird, the black-fronted tern (Chlidonias albostriatus); a specialist of the spatially and temporally dynamic environments of braided rivers. Location: New Zealand Methods: We used a three-pronged approach based on 17 microsatellites, two mitochondrial loci (cytochrome b / control region), and phenotypic data (head-bill length, bill depth, wing length, weight). We determined large-scale genetic structure throughout the whole breeding range (approx. 150,000 km2), calculated genetic divergence of breeding populations, and tested for isolation-by-distance between populations. We investigated the level of fine-scale genetic structure based on spatial autocorrelation analyses and assessed the presence of a body size cline based on phenotypic data. Lastly, we compared phenotypic divergence (PST) and the level of divergence by genetic drift (FST) among breeding populations to test for underlying mechanisms of population differentiation. Results: Nuclear and mitochondrial DNA showed that across their range black-fronted terns were effectively panmictic, with low genetic divergence between breeding colonies overall and no isolation-by-distance. However, at fine geographical scales black-fronted terns accrued significant genetic structure for distances up to 75 km, primarily driven by males, indicating more frequent female dispersal. Furthermore, a phenotypic cline in accordance with Bergmann's rule was evident. PST exceeded FST in three traits, suggestive of local adaptation. Main conclusions: Significant fine-scale structure can be present in highly mobile, specialist species while not affecting spatial structures at larger scales. Hence, methodologies applied to both whole landscapes and local scales are important to appropriately estimate connectivity in dynamic metapopulations and investigate the processes behind connectivity. Conservation management will need to include protecting currently uninhabited patches to facilitate natural colonisation of suitable habitat. For black-fronted terns, managing whole catchments throughout the entire breeding range would be preferable to managing single patches.
Data from: Allometric scaling of eDNA production in stream-dwelling brook trout (Salvelinus fontinalis) inferred from population size structure
<p>Environmental DNA (eDNA) concentration exhibits a positive correlation with organism abundance in nature, but modelling this relationship could be substantially improved by incorporating the biology of eDNA production. A recent model (Yates et al. 2020) extended models of physiological allometric scaling to eDNA production, hypothesizing that brook trout eDNA production scales non-linearly with mass as a power-function with scaling coefficients < 1 in lakes. To validate this hypothesis, we re-analysed data from Wilcox et al. (2016) that examined the correlation between eDNA concentration and brook trout abundance in streams. We found that allometrically scaled mass (ASM) (e.g. ∑(individual mass<sup>0.36</sup>) best described patterns of eDNA concentration across streams (r<sup>2</sup> = 0.43). ASM<sup> </sup>exhibited substantially improved model fit relative to biomass (r<sup>2</sup> = 0.31, ∆AIC = 5.19), indicating that eDNA production did not scale linearly with biomass. However, the explanatory power of ASM was comparable to density (r<sup>2</sup> = 0.40, ∆AIC = 1.25). Additionally, the optimal scaling coefficient estimated from the data (0.36) was substantially lower than that found in Yates et al. (2020) (0.72). Discrepancies between datasets could be attributable to ecological differences between study habitats (streams vs lakes) or due to the exclusion of juveniles (i.e. individuals < 75 mm) that can be abundant in stream environments. Nevertheless, this study adds to the growing body of literature demonstrating that individual eDNA production does not scale linearly with biomass.</p>
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Allen Brain Atlas
Allen Brain Atlas is an Allen Institute collection of brain map atlases, datasets, APIs, and analysis tools covering mouse, human, and non-human primate brain resources.
Annotated Behaviour and Observability Dataset (ABODe)
ABODe is a University of Edinburgh DataShare dataset for behavior classification in group-housed mice using home-cage video, identities, bounding boxes, ground-plate positions, and annotator labels.
DANDI Archive for NWB datasets
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.