41 research outputs found

    Genomic basis of ecological niche divergence among cryptic sister species of non-biting midges

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    Background: There is a lack of understanding the evolutionary forces driving niche segregation of closely related organisms. In addition, pinpointing the genes driving ecological divergence is a key goal in molecular ecology. Here, larval transcriptome sequences obtained by next-generation-sequencing are used to address these issues in a morphologically cryptic sister species pair of non-biting midges (Chironomus riparius and C. piger). Results: More than eight thousand orthologous open reading frames were screened for interspecific divergence and intraspecific polymorphisms. Despite a small mean sequence divergence of 1.53% between the sister species, 25.1% of 18,115 observed amino acid substitutions were inferred by α statistics to be driven by positive selection. Applying McDonald-Kreitman tests to 715 alignments of gene orthologues identified eleven (1.5%) genes driven by positive selection. Conclusions: Three candidate genes were identified as potentially responsible for the observed niche segregation concerning nitrite concentration, habitat temperature and water conductivity. Additionally, signs of positive selection in the hydrogen sulfide detoxification pathway were detected, providing a new plausible hypothesis for the species’ ecological differentiation. Finally, a divergently selected, nuclear encoded mitochondrial ribosomal protein may contribute to reproductive isolation due to cytonuclear coevolution

    Sci-Hub provides access to nearly all scholarly literature

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    The website Sci-Hub enables users to download PDF versions of scholarly articles, including many articles that are paywalled at their journal\u27s site. Sci-Hub has grown rapidly since its creation in 2011, but the extent of its coverage was unclear. Here we report that, as of March 2017, Sci-Hub\u27s database contains 68.9% of the 81.6 million scholarly articles registered with Crossref and 85.1% of articles published in toll access journals. We find that coverage varies by discipline and publisher, and that Sci-Hub preferentially covers popular, paywalled content. For toll access articles, we find that Sci-Hub provides greater coverage than the University of Pennsylvania, a major research university in the United States. Green open access to toll access articles via licit services, on the other hand, remains quite limited. Our interactive browser at https://greenelab.github.io/scihub allows users to explore these findings in more detail. For the first time, nearly all scholarly literature is available gratis to anyone with an Internet connection, suggesting the toll access business model may become unsustainable

    Open Humans:A platform for participant-centered research and personal data exploration

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    Background Many aspects of our lives are now digitized and connected to the internet. As a result, individuals are now creating and collecting more personal data than ever before. This offers an unprecedented chance for human-participant research ranging from the social sciences to precision medicine. With this potential wealth of data comes practical problems (e.g., how to merge data streams from various sources), as well as ethical problems (e.g., how best to balance risks and benefits when enabling personal data sharing by individuals). Results To begin to address these problems in real time, we present Open Humans, a community-based platform that enables personal data collections across data streams, giving individuals more personal data access and control of sharing authorizations, and enabling academic research as well as patient-led projects. We showcase data streams that Open Humans combines (e.g., personal genetic data, wearable activity monitors, GPS location records, and continuous glucose monitor data), along with use cases of how the data facilitate various projects. Conclusions Open Humans highlights how a community-centric ecosystem can be used to aggregate personal data from various sources, as well as how these data can be used by academic and citizen scientists through practical, iterative approaches to sharing that strive to balance considerations with participant autonomy, inclusion, and privacy.publishedVersio

    Contours of citizen science: a vignette study

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    Citizen science has expanded rapidly over the past decades. Yet, defining citizen science and its boundaries remained a challenge, and this is reflected in the literature-for example in the proliferation of typologies and definitions. There is a need for identifying areas of agreement and disagreement within the citizen science practitioners community on what should be considered as citizen science activity. This paper describes the development and results of a survey that examined this issue, through the use of vignettes-short case descriptions that describe an activity, while asking the respondents to rate the activity on a scale from 'not citizen science' (0%) to 'citizen science' (100%). The survey included 50 vignettes, of which five were developed as clear cases of not-citizen science activities, five as widely accepted citizen science activities and the others addressing 10 factors and 61 sub-factors that can lead to controversy about an activity. The survey has attracted 333 respondents, who provided over 5100 ratings. The analysis demonstrates the plurality of understanding of what citizen science is and calls for an open understanding of what activities are included in the field

    Looking into Pandora's box: the content of Sci-Hub and its usage [version 1; referees: 2 approved, 2 approved with reservations]

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    Despite the growth of Open Access, potentially illegally circumventing paywalls to access scholarly publications is becoming a more mainstream phenomenon. The web service Sci-Hub is amongst the biggest facilitators of this, offering free access to around 62 million publications. So far it is not well studied how and why its users are accessing publications through Sci-Hub. By utilizing the recently released corpus of Sci-Hub and comparing it to the data of ~28 million downloads done through the service, this study tries to address some of these questions. The comparative analysis shows that both the usage and complete corpus is largely made up of recently published articles, with users disproportionately favoring newer articles and 35% of downloaded articles being published after 2013. These results hint that embargo periods before publications become Open Access are frequently circumnavigated using Guerilla Open Access approaches like Sci-Hub. On a journal level, the downloads show a bias towards some scholarly disciplines, especially Chemistry, suggesting increased barriers to access for these. Comparing the use and corpus on a publisher level, it becomes clear that only 11% of publishers are highly requested in comparison to the baseline frequency, while 45% of all publishers are significantly less accessed than expected. Despite this, the oligopoly of publishers is even more remarkable on the level of content consumption, with 80% of all downloads being published through only 9 publishers. All of this suggests that Sci-Hub is used by different populations and for a number of different reasons, and that there is still a lack of access to the published scientific record. A further analysis of these openly available data resources will undoubtedly be valuable for the investigation of academic publishing

    Characterizing the hologenome of Lasallia pustulata and tracing genomic footprints of lichenization

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    The lichen symbiosis – consisting of fungal mycobionts and photoautotroph photobionts (green algae or cyanobacteria) – is globally successful. It covers an estimated 6% of the global surface with habitats ranging from deserts to the arctic. This success is reflected in the diversity of the mycobionts, with around 21% of all fungal species participating in lichen symbioses that can be facultative or obligate. Lichenization is furthermore evolutionary old, with fossil evidence for lichens reaching back 415 million years. For an individual fungal lineage, the Lecanoromycetes, the lichenization happened around 300 million years ago. This longstanding symbiotic relationship and the diversity of observed symbiotic dependency make them promising models to study the genomic consequences that follow the establishment of symbioses. Despite this, only little is known about the genomic effects of lichenization and extreme symbiotic dependency. To fill this gap we sequenced the hologenome of the lichen Lasallia pustulata, where the mycobiont could so far not been cultivated, suggesting that it might be more dependent on its symbionts. As the poor culturability of lichen symbionts renders their genomes inaccessible to standard sequencing practices, we evaluated the extent to which different metagenome sequencing- and de novo assembly-strategies can be used to sequence and reconstruct the genomes of the individual symbionts. We find that the abundances of individual genomes present in the L. pustulata hologenome vary substantially, with the mycobiont being most abundant. Using in silico generated data sets and real Illumina sequencing data for L. pustulata we observe that the skewed abundances prevent a contiguous assembly of the underrepresented genomes when using only short-read sequencing. We conclude that short-read sequencing can offer first insights into lichen hologenomes. The fragmentation of the reconstructions hinders downstream analyses into the genomic consequences of lichenization though, as these are focused on identifying the gain and loss of genes. We thus demonstrate a hybrid genome assembly strategy that is based on both short- and long-read sequencing. We show that this strategy is capable of creating highly contiguous genome reconstructions, not only for the L. pustulata mycobiont but also its photobiont Trebouxia sp., along with substantial amounts of the bacterial microbiome. A subsequent analysis of the microbiome of L. pustulata – performed over nine different samples collected in Germany and Italy – showed a stable taxonomic composition across the geographic range. We find that Acidobacteriaceae, which are known to thrive in nutrient poor habitats, are the dominant taxa. These would make them well adapted for the co-habitation with L. pustulata, which largely grows on rocks. Whether the Acidobacteriaceae are functionally involved in the lichen symbiosis is unclear so far. As further comparative genomic studies rely on comprehensive genome annotations, we evaluate the completeness and fidelity of the gene annotations for the mycobiont L. pustulata as well as four further Lecanoromycetes. This reveals that un- and mis-annotated genes impact all evaluated genomes, with artificially joined genes and unannotated genes having the largest impact. In addition to these factors we find that the sequence composition – especially G/C-rich inverted repeats – lead to sequencing errors that interfere with the gene prediction. We minimize the effects of these artifacts through a rigorous curation. Given the extremely sparse taxon sampling of available green alga genomes, we focus our search for the genomic footprints of lichenization on the mycobionts. We compare the genomes of the Lecanoromycetes to their closest relatives, the Eurotiomycetes and Dothideomycetes. This reveals that the last common ancestor of the Lecanoromycetes has lost around 10% of its genes after they split from the non-lichenized ancestor they share with the Eurotiomycetes. These losses are furthermore enriched, showing an excessive loss of genes involved with the degradation of polysaccharides. The loss of these genes fits a change from an ancestral saprotrophic lifestyle that depends on degrading complex plant matter, to the symbiotic lifestyle that relies on simpler nutrients provided by the photobionts. While the last common ancestor of the Lecanoromycetes additionally gained around 400 genes these could so far not be further characterized due to a lack of functionally annotated reference data. As the mycobiont L. pustulata could so far not been grown in axenic culture, we initially expected to find an extensive genomic remodeling compared to the other mycobionts that easily grow in culture. We do not find evidence for this. Analyzing both the contraction of gene families and the loss of genes, we observe that L. pustulata and Umbilicaria muehlenbergii – its close relative that is easily grown in culture – share most of these. Furthermore, L. pustulata does not show an excessive loss of evolutionary old and well-conserved genes. These effects are mirrored on the functional level, as neither gene family contractions nor gene losses show a functional enrichment. This is partially due to the lack of functional reference data, analogous to the genes gained in the Lecanoromycetes, rendering their characterization hard. Thus, further studies on the genomic consequences of lichenization and differences in symbiotic dependence will have to be conducted, including larger taxon sets. This will be even more important for the photobionts, as the Chlorophyta are even more sparsely sampled today, hindering an effective functional and evolutionary study

    De novo Assembly and Comparative Genomics on Eukaryotic Species Mixtures

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    <p>My poster for the RECOMB15 Comparative Genomics Conference.</p

    Sci-Hub download log of 2017

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    <p>The full 2017 download log of Sci-Hub. Originally published on the Sci-Hub Twitter account at https://twitter.com/Sci_Hub/status/954095639859814402</p> <p>Republished here to provide a stable mirror of the data. The gunzipped file is ~14 GB in size. MD5 sum for gzipped file is 53c8a599e6467c8f4a62a32249c7e63c</p> <p>Columns in the data file:</p> <ol> <li>Timestamp (yyyy-MM-dd HH:mm:ss)</li> <li>DOI</li> <li>IP identifier</li> <li>User identifier</li> <li>Country according to GeoIP</li> <li>City according to GeoIP</li> <li>Latitude</li> <li>Longitude</li> </ol
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