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19,342 results for “sequence”
Data from: Genome sequence of dwarf birch (Betula nana) and cross-species RAD markers
New sequencing technologies allow development of genome-wide markers for any genus of ecological interest, including plant genera such as Betula (birch) that have previously proved difficult to study due to widespread polyploidy and hybridisation. We present a de novo reference genome sequence assembly, from 67X short read coverage, of Betula nana (dwarf birch) – a diploid that is the keystone woody species of sub-arctic scrub communities but of conservation concern in Britain. We also present 100bp PstI RAD markers for B. nana and closely related Betula tree species. Assembly of RAD markers in 15 individuals by alignment to the reference B. nana genome yielded 44k-86k RAD loci per individual, whereas de novo RAD assembly yielded 64k-121k loci per individual. Of the loci assembled by the de novo method, 3k homologous loci were found in all 15 individuals studied, and 35k in 10 or more individuals. Matching of RAD loci to RAD locus catalogs from the B. nana individual used for the reference genome, showed similar numbers of matches from both methods of RAD locus assembly but indicated that the de novo RAD assembly method may over-assemble some paralogous loci. In 12 individuals hetero-specific to B. nana 37k-47k RAD loci matched a catalog of RAD loci from the B. nana individual used for the reference genome, whereas 44k-60k RAD loci aligned to the B. nana reference genome itself. We present a preliminary study of allele sharing among species, demonstrating the utility of the data for introgression studies and for the identification of species-specific alleles.
Data from: Two new species of Limbodessus diving beetles from New Guinea - short verbal descriptions flanked by online content (digital photography, μCT scans, drawings and DNA sequence data)
Background: To date only one species of Limbodessus diving beetles has been reported from the Island of New Guinea, L. compactus (Clark, 1862), which is widerspread in the Australian region. New information: We describe two new species of microendemic New Guinea Limbodessus and use a compact descriptive format flanked by enriched online content in wiki powered species pages. Limbodessus baliem sp.n. is described from ca. 1,600 m altitude in the Baliem Valley of Papua and Limbodessus alexanderi sp.n. from >3,000 m altitude north of Sugapa, Papua. Based on our analysis, we also transfer three species from other genera to Limbodessus Guignot, 1939, with the following changes: Limbodessus deflectus (Ordish, 1966), new combination; Limbodessus leveri (J. Balfour-Browne, 1944), new combination; and Limbodessus plicatus (Sharp, 1882), new combination.
Data from: Genotyping-by-sequencing for Populus population genomics: an assessment of genome sampling patterns and filtering approaches
Continuing advances in nucleotide sequencing technology are inspiring a suite of genomic approaches in studies of natural populations. Researchers are faced with data management and analytical scales that are increasing by orders of magnitude. With such dramatic advances comes a need to understand biases and error rates, which can be propagated and magnified in large-scale data acquisition and processing. Here we assess genomic sampling biases and the effects of various population-level data filtering strategies in a genotyping-by-sequencing (GBS) protocol. We focus on data from two species of Populus, because this genus has a relatively small genome and is emerging as a target for population genomic studies. We estimate the proportions and patterns of genomic sampling by examining the Populus trichocarpa genome (Nisqually-1), and demonstrate a pronounced bias towards coding regions when using the methylation-sensitive ApeKI restriction enzyme in this species. Using population-level data from a closely related species (P. tremuloides), we also investigate various approaches for filtering GBS data to retain high-depth, informative SNPs that can be used for population genetic analyses. We find a data filter that includes the designation of ambiguous alleles resulted in metrics of population structure and Hardy-Weinberg equilibrium that were most consistent with previous studies of the same populations based on other genetic markers. Analyses of the filtered data (27,910 SNPs) also resulted in patterns of heterozygosity and population structure similar to a previous study using microsatellites. Our application demonstrates that technically and analytically simple approaches can readily be developed for population genomics of natural populations.
Data from: A high-density exome capture genotype-by-sequencing panel for forestry breeding in Pinus radiata
Development of genome-wide resources for application in genomic selection or genome-wide association studies, in the absences of full reference genomes, present a challenge to the forestry industry, where longer breeding cycles could benefit from the accelerated selection possible through marker-based breeding value predictions. In particular, large conifer megagenomes require a strategy to reduce complexity, whilst ensuring genome-wide coverage is achieved. Using a transcriptome-based reference template, we have successfully developed a high density exome capture genotype-by-sequencing panel for radiata pine (Pinus radiata D.Don), capable of capturing in excess of 80,000 single nucleotide polymorphism (SNP) markers with a minor allele frequency above 0.03 in the population tested. This represents approximately 29,000 gene models from a core set of 48,914 probes. A set of 704 SMP markers capable of pedigree reconstruction and differentiating individual genotypes were tested within two full-sib mapping populations. While as few as 70 markers could reconstruct parentage in almost all cases, the impact of missing genotypes was noticeable in several offspring. Therefore, sets of 60 sets of 110 randomly selected SNP markers were compared for both parentage reconstruction and clone differentiation. The performance in parentage reconstruction showed little variation over 60 iterations. However, there was notable variation in discriminatory power between closely related individuals, indicating a higher density SNP marker panel may be required to elucidate hidden relationships in complex pedigrees.
Data from: Finding the right coverage: The impact of coverage and sequence quality on SNP genotyping error rates
Restriction-enzyme-based sequencing methods enable the genotyping of thousands of single nucleotide polymorphism (SNP) loci in non-model organisms. However, in contrast to traditional genetic markers, genotyping error rates in SNPs derived from restriction-enzyme-based methods remain largely unknown. Here, we estimated genotyping error rates in SNPs genotyped with double digest RAD sequencing from Mendelian incompatibilities in known mother-offspring dyads of Hoffman's two-toed sloth (Choloepus hoffmanni) across a range of coverage and sequence quality criteria, for both reference-aligned and de novo-assembled datasets. Genotyping error rates were more sensitive to coverage than sequence quality and low coverage yielded high error rates, particularly in de novo-assembled datasets. For example, coverage ≥5 yielded median genotyping error rates of ≥0.03 and ≥0.11 in reference-aligned- and de novo-assembled datasets, respectively. Genotyping error rates declined to ≤0.01 in reference-aligned datasets with a coverage >30, but remained >0.04 in the de novo-assembled datasets. We observed approximately 10- and 13-fold declines in the number of loci sampled in the reference-aligned and de novo-assembled datasets when coverage was increased from >5 to >30 at quality score ≥30, respectively. Finally, we assessed the effects of genotyping coverage on a common population genetic application, parentage assignments, and showed that the proportion of incorrectly assigned maternities was relatively high at low coverage. Overall, our results suggest that the tradeoff between sample size and genotyping error rates be considered prior to building sequencing libraries, reporting genotyping error rates become standard practice, and that effects of genotyping errors on inference be evaluated in restriction-enzyme-based SNP studies.
Data from: Targeted next-generation sequencing panels in the diagnosis of Charcot Marie Tooth disease
Objective: To investigate the effectiveness of targeted NGS panels in achieving a molecular diagnosis in CMT and related disorders in a clinical setting Methods: We prospectively enrolled 220 patients from two tertiary referral centres, one in London, UK (n=120) and one in Iowa, US (n=100) in whom a targeted CMT NGS panel had been requested as a diagnostic test. PMP22 duplication/deletion was previously excluded in demyelinating cases. We reviewed the genetic and clinical data upon completion of the diagnostic process. Results: After targeted NGS sequencing a definite molecular diagnosis, defined as a pathogenic or likely pathogenic variant, was reached in 30% of cases (n=67). The diagnostic rate was similar in London (32%) and Iowa (29%). Variants of unknown significance were found in an additional 33% of cases. Mutations in GJB1, MFN2, MPZ accounted for 39% of cases who received genetic confirmation, while the remainder of positive cases had mutations in diverse genes, including SH3TC2, GDAP1, IGHMBP2, LRSAM1, FDG4, GARS and another 12 less common genes. Copy number changes in PMP22, MPZ, MFN2, SH3TC2 and FDG4 were also accurately detected. A definite genetic diagnosis was more likely in cases with an early onset, a positive family history of neuropathy or consanguinity and a demyelinating neuropathy. Conclusions: NGS panels are effective tools in the diagnosis of CMT leading to the genetic confirmation in one third cases negative for PMP22 duplication/deletion, thus highlighting how rarer and previously undiagnosed subtypes represent today a relevant part of the genetic landscape of CMT.
Data from: Phylogenetic systematics of subtribe Spiranthinae (Orchidaceae: Orchidoideae: Cranichideae) based on nuclear and plastid DNA sequences of a nearly complete generic sample
Subtribe Spiranthinae is the most species-rich lineage of terrestrial Neotropical orchids, encompassing > 500 species and 40 genera. We conducted maximum parsimony and maximum likelihood phylogenetic analyses of DNA sequence data of plastid matK-trnK and trnL-trnF and nuclear ribosomal ITS sequences for 36 genera and 182 species of Spiranthinae plus appropriate outgroups. The results strongly support monophyly of Spiranthinae (minus Discyphus, Discyphinae and Galeottiella, Galeottiellinae) and five major lineages, namely monospecific Cotylolabium (sister to the remaining Spiranthinae) and the Eurystyles, Pelexia, Spiranthes and Stenorrhynchos clades. Eighteen of the 27 genera of Spiranthinae for which more than one species was included in our analyses are monophyletic. Paraphyly of large genera, such as Cyclopogon and Sarcoglottis, resulted from segregation of particular species or groups of species exhibiting minor modifications of structures directly involved in pollination (e.g. nectary, rostellum and viscidium). Conversely, polyphyly has resulted from convergent evolution of floral attributes in distantly related species (e.g. Mesadenus). Some of the morphological characters used traditionally for generic delimitation and in non-molecular cladistic analyses of Spiranthinae are discussed against the evolutionary framework set by our molecular trees, emphasizing putative synapomorphies and problems derived from inappropriate character coding or incorrect homology assessments. Our ancestral area analysis indicates that Spiranthinae originated in eastern South America, with subsequent migrations and secondary radiations in Mesoamerica and North America, plus a derived migration from the latter region to the Old World (Spiranthes).
Data from: Identification and characterization of sex-associated loci in sockeye salmon using genotyping-by-sequencing and comparison with a sex-determining assay based on the sdY gene
Loci that can be used to screen for sex in salmon can provide important information for study of both wild and cultured populations. Here, we tested for associations between sex and genotypes at thousands of loci available from a genotyping-by-sequencing (GBS) dataset to discover sex-associated loci in sockeye salmon (Oncorhynchus nerka). We discovered seven sex-associated loci, developed high-throughput assays for two loci, and tested the utility of these two assays in eight collections of sockeye salmon sampled throughout North America. We also screened an existing assay based on the master sex-determining gene in salmon (sdY) in these collections. The ability of GBS-derived loci to assign fish to their phenotypic sex varied substantially among collections suggesting that recombination between the loci that we discovered and the sex-determining gene has occurred. Assignment accuracy to phenotypic sex was much higher with the sdY assay but was still less than 100%. Alignment of sequences from GBS-derived loci to draft genomes for two salmonids provided strong evidence that many of these loci are found on the chromosome orthologous to the known sex chromosome in sockeye salmon. Our study is the first to describe the approximate location of the sex-determining region in sockeye salmon and indicates that sdY is also the master sex-determining gene in this species. However, discordances between sdY genotypes and phenotypic sex and the variable performance of GBS-derived loci warrant more research.
Data from: Phylogenomics of horned lizards (genus: Phrynosoma) using targeted sequence capture data
New genome sequencing techniques are enabling phylogenetic studies to scale-up from using a handful of loci to hundreds or thousands of loci from throughout the genome. In this study, we use targeted sequence capture (TSC) data from 540 ultraconserved elements and 44 protein-coding genes to estimate the phylogenetic relationships among all 17 species of horned lizards in the genus Phrynosoma. Previous molecular phylogenetic analyses of Phrynosoma based on a few nuclear genes, restriction site associated DNA (RAD) sequencing, or mitochondrial DNA (mtDNA) have produced conflicting relationships. Some of these conflicts are likely the result of rapid speciation at the start of Phrynosoma diversification, whereas other examples of gene tree discordance appear to be caused by active and residual traces of hybridization. Concatenation and coalescent-based species tree phylogenetic analyses of these new TSC data support the same topology, and a divergence dating analysis suggests that the Phrynosoma crown group is up to 30 million years old. The new phylogenomic tree supports the recognition of four main clades within Phrynosoma, including Anota (P. mcallii, P. solare, and the P. coronatum complex), Doliosaurus (P. modestum, P. goodei, and P. platyrhinos), Tapaja (P. ditmarsi, P. douglasii, P. hernandesi, and P. orbiculare), and Brevicauda (P. braconnieri, P. sherbrookei, and P. taurus). The phylogeny provides strong support for the relationships among all species of Phrynosoma and provides a robust new framework for conducting comparative analyses.
Data from: High-throughput sequencing of nematode communities from total soil DNA extractions
Background: Nematodes are extremely diverse and numbers of species are predicted to be more than a million. Studies on nematode diversity are difficult and laborious using standard methods such as identification based on morphology and therefore high-throughput sequencing is an attractive alternative. Generally, primers that have been used for generating amplicons for sequencing are not nematode specific and also amplify other groups such as fungi and plantae. Thus a nematode enrichment step must be included that may introduce biases. Results: An amplification strategy, including a new primer, which selectively amplifies nematodes and other metazoans was developed. When this strategy was tested on DNA templates from a set of 22 agricultural soils, we obtained 64.4 % sequences of nematode origin in total, whereas the remaining sequences were almost entirely metazoan. The nematode sequences were derived from a broad taxonomic range and most sequences were from nematode taxa that have previously been found to be abundant in soil such as Tylenchida, Rhabditida, Dorylaimida, Triplonchida and Araeolaimida. Conclusions: This amplification and sequencing strategy for assessing nematode diversity was demonstrated to be able to collect a broad taxonomy of nematodes without prior enrichment and thus the method will be highly valuable in ecological studies of nematodes. Keywords: nematode, community, next-generation sequencing, SSU, diversity, 18S, rDNA
Data from: Transatlantic secondary contact in Atlantic salmon, comparing microsatellites, a SNP array, and Restriction Associated DNA sequencing for the resolution of complex spatial structure
Identification of discrete and unique assemblages of individuals or populations is central to the management of exploited species. Advances in population genomics provide new opportunities for re-evaluating existing conservation units but comparisons among approaches remain rare. We compare the utility of RAD-seq, a single nucleotide polymorphism (SNP) array and a microsatellite panel to resolve spatial structuring under a scenario of possible trans-Atlantic secondary contact in a threatened Atlantic Salmon, Salmo salar, population in southern Newfoundland. Bayesian clustering indentified two large groups subdividing the existing conservation unit and multivariate analyses indicated significant similarity in spatial structuring among the three data sets. mtDNA alleles diagnostic for European ancestry displayed increased frequency in southeastern Newfoundland and were correlated with spatial structure in all marker types. Evidence consistent with introgression among these two groups was present in both SNP data sets but not the microsatellite data. Asymmetry in the degree of introgression was also apparent in SNP data sets with evidence of gene flow towards the east or European type. This work highlights the utility of RAD-seq based approaches for the resolution of complex spatial patterns, resolves a region of trans-Atlantic secondary contact in Atlantic Salmon in Newfoundland and demonstrates the utility of multiple marker comparisons in identifying dynamics of introgression.
Data from: "Diagnostic SNPs for inferring population structure in American mink (Neovison vison) identified through RAD sequencing" in Genomic Resources Notes accepted 1 October 2014 to 30 November 2014
The article documents the public availability of RAD sequencing data and generated SNPs for the American mink (Neovison vison). 224,095 polymorphic loci were identified from 14 mink from which primers were designed for a subset of 380 SNPs. The panel was tested on 211 mink. Fisher's F-statistics (Fis, FIT and FST) as well as observed (HO), expected (HE) and unbiased expected (uHE) heterozygosity was calculated for the SNPs and 194 SNPs was validated as being useful for population genetic studies.
Data from: Genome sequence and population declines in the critically endangered greater bamboo lemur (Prolemur simus) and implications for conservation
Background: The greater bamboo lemur (Prolemur simus) is a member of the Family Lemuridae that is unique in their dependency on bamboo as a primary food source. This Critically Endangered species lives in small forest patches in eastern Madagascar, occupying a fraction of its historical range. Here we sequence the genome of the greater bamboo lemur for the first time, and provide genome resources for future studies of this species that can be applied across its distribution. Results: Following whole genome sequencing of five individuals we identified over 152,000 polymorphic single nucleotide variants (SNVs), and evaluated geographic structuring across nearly 19k SNVs. We characterized a stronger signal associated with a north-south divide than across elevations for our limited samples. We also evaluated the demographic history of this species, and infer a dramatic population crash. This species had the largest effective population size (estimated between ~900,000 to one million individuals) between approximately 60,000-90,000 years before present (ybp), during a time in which global climate change affected terrestrial mammals worldwide. We also note the single sample from the northern portion of the extant range had the largest effective population size around 35,000 ybp. Conclusions: From our whole genome sequencing we recovered an average genomic heterozygosity of 0.0037%, comparable to other lemurs. Our demographic history reconstructions recovered a probable climate-related decline (60-90,000 ybp), followed by a second population decrease following human colonization, which has reduced the species to a census size of approximately 1,000 individuals. The historical distribution was likely a vast portion of Madagascar, minimally estimated at 44,259 km2, while the contemporary distribution is only ~1,700 km2. The decline in effective population size of 89-99.9% corresponded to a vast range retraction. Conservation management of this species is crucial to retain genetic diversity across the remaining isolated populations.
Data from: A NGS approach to the encrusting Mediterranean sponge Crella elegans (Porifera, Demospongiae, Poecilosclerida): transcriptome sequencing, characterization and overview of the gene expression along three life cycle stages
Sponges can be dominant organisms in many marine and freshwater habitats where they play essential ecological roles. They also represent a key group to address important questions in early metazoan evolution. Recent approaches for improving knowledge on sponge biological and ecological functions as well as on animal evolution have focused on the genetic toolkits involved in ecological responses to environmental changes (biotic and abiotic), development and reproduction. These approaches are possible thanks to newly available, massive sequencing technologies–such as the Illumina platform, which facilitate genome and transcriptome sequencing in a cost-effective manner. Here we present the first NGS (next-generation sequencing) approach to understanding the life cycle of an encrusting marine sponge. For this we sequenced libraries of three different life cycle stages of the Mediterranean sponge Crella elegans and generated de novo transcriptome assemblies. Three assemblies were based on sponge tissue of a particular life cycle stage, including non-reproductive tissue, tissue with sperm cysts and tissue with larvae. The fourth assembly pooled the data from all three stages. By aggregating data from all the different life cycle stages we obtained a higher total number of contigs, contigs with blast hit and annotated contigs than from one stage-based assemblies. In that multi-stage assembly we obtained a larger number of the developmental regulatory genes known for metazoans than in any other assembly. We also advance the differential expression of selected genes in the three life cycle stages to explore the potential of RNA-seq for improving knowledge on functional processes along the sponge life cycle.
Data from: Characterization of the transcriptome, nucleotide sequence polymorphism, and natural selection in the desert adapted mouse Peromyscus eremicus
As a direct result of intense heat and aridity, deserts are thought to be among the most harsh of environments, particularly for their mammalian inhabitants. Given that osmoregulation can be challenging for these animals, with failure resulting in death, strong selection should be observed on genes related to the maintenance of water and solute balance. One such animal, Peromyscus eremicus, is native to the desert regions of the southwest United States and may live its entire life without oral fluid intake. As a first step toward understanding the genetics that underlie this phenotype, we present a characterization of the P. eremicus transcriptome. We assay four tissues (kidney, liver, brain, testes) from a single individual and supplement this with population level renal transcriptome sequencing from 15 additional animals. We identified a set of transcripts undergoing both purifying and balancing selection based on estimates of Tajima's D. In addition, we used the branch-site test to identify a transcript—Slc2a9, likely related to desert osmoregulation—undergoing enhanced selection in P. eremicus relative to a set of related non-desert rodents.
Data from: 16S rRNA amplicon sequencing for epidemiological surveys of bacteria in wildlife
The human impact on natural habitats is increasing the complexity of human-wildlife interactions and leading to the emergence of infectious diseases worldwide. Highly successful synanthropic wildlife species, such as rodents, will undoubtedly play an increasingly important role in transmitting zoonotic diseases. We investigated the potential for recent developments in 16S rRNA amplicon sequencing to facilitate the multiplexing of the large numbers of samples needed to improve our understanding of the risk of zoonotic disease transmission posed by urban rodents in West Africa. In addition to listing pathogenic bacteria in wild populations, as in other high-throughput sequencing (HTS) studies, our approach can estimate essential parameters for studies of zoonotic risk, such as prevalence and patterns of coinfection within individual hosts. However, the estimation of these parameters requires cleaning of the raw data to mitigate the biases generated by HTS methods. We present here an extensive review of these biases and of their consequences, and we propose a comprehensive trimming strategy for managing these biases. We demonstrated the application of this strategy using 711 commensal rodents, including 208 Mus musculus domesticus, 189 Rattus rattus, 93 Mastomys natalensis, and 221 Mastomys erythroleucus, collected from 24 villages in Senegal. Seven major genera of pathogenic bacteria were detected in their spleens: Borrelia, Bartonella, Mycoplasma, Ehrlichia, Rickettsia, Streptobacillus, and Orientia. Mycoplasma, Ehrlichia, Rickettsia, Streptobacillus, and Orientia have never before been detected in West African rodents. Bacterial prevalence ranged from 0% to 90% of individuals per site, depending on the bacterial taxon, rodent species, and site considered, and 26% of rodents displayed coinfection. The 16S rRNA amplicon sequencing strategy presented here has the advantage over other molecular surveillance tools of dealing with a large spectrum of bacterial pathogens without requiring assumptions about their presence in the samples. This approach is therefore particularly suitable to continuous pathogen surveillance in the context of disease-monitoring programs.
Data from: Genotyping by sequencing reveals contrasting patterns of population structure, ecologically mediated divergence and long-distance dispersal in North American palms
Comparative studies can provide powerful insights into processes that affect population divergence and thereby help to elucidate the mechanisms by which contemporary populations may respond to environmental change. Furthermore, approaches such as genotyping by sequencing (GBS) provide unprecedented power for resolving genetic differences among species and populations. We therefore used GBS to provide a genome-wide perspective on the comparative population structure of two palm genera, Washingtonia and Brahea, on the Baja California peninsula, a region of high landscape and ecological complexity. First, we used phylogenetic analysis to address taxonomic uncertainties among five currently recognised species. We resolved three main clades, the first corresponding to W. robusta and W. filifera, the second to B. brandegeei and B. armata, and the third to B. edulis from Guadalupe Island. Focusing on the first two clades, we then delved deeper by investigating the underlying population structure. Striking differences were found, with GBS uncovering four distinct Washingtonia populations and identifying a suite of loci associated with temperature, consistent with ecologically mediated divergence. By contrast, individual mountain ranges could be resolved in Brahea and few loci were associated with environmental variables, implying a more prominent role of neutral divergence. Finally, evidence was found for long-distance dispersal events in Washingtonia but not Brahea, in line with knowledge of the dispersal mechanisms of these palms including the possibility of human-mediated dispersal. Overall, our study demonstrates the power of GBS together with a comparative approach to elucidate markedly different patterns of genome-wide divergence mediated by multiple effectors.
Data from: Extent and variability of interstitial telomeric sequences and their effects on estimates of telomere length
Telomeres often shorten with time, although this varies between tissues, individuals and species, and their length and/or rate of change may reflect fitness and rate of senescence. Measurement of telomeres is increasingly important to ecologists, yet the relative merits of different methods for estimating telomere length are not clear. In particular the extent to which interstitial telomere sequences (ITSs), telomere repeats located away from chromosomes ends, confound estimates of telomere length is unknown. Here we present a method to estimate the extent of ITS within a species and variation among individuals. We estimated the extent of ITS by comparing the amount of label hybridized to in-gel telomere restriction fragments (TRF) before and after the TRFs were denatured. This protocol produced robust and repeatable estimates of the extent of ITS in birds. In five species, the amount of ITS was substantial, ranging from 15% to 40% of total telomeric sequence DNA. In addition, the amount of ITS can vary significantly among individuals within a species. Including ITSs in telomere length calculations always underestimated telomere length because most ITSs are shorter than most telomeres. The magnitude of that error varies with telomere length and is larger for longer telomeres. Estimating telomere length using methods that incorporate ITSs, such as Southern blot TRF and quantitative PCR analyses reduces an investigator's power to detect difference in telomere dynamics between individuals or over time within an individual.
Data from: Contrasting patterns of divergence at the regulatory and sequence level in European Daphnia galeata natural populations
Understanding the genetic basis of local adaptation has long been the focus of evolutionary biology. Recently there has been increased interest in deciphering the evolutionary role of Daphnia's plasticity and the molecular mechanisms of local adaptation. Using transcriptome data, we assessed the differences in gene expression profiles and sequences within and between four European Daphnia galeata populations. To distinguish neutral from adaptive differentiation, we corrected for phylogenetic differentiation of Daphnia populations. We also applied a "transcriptome scan" approach to investigate the role of natural selection in shaping divergent expression profiles among populations. Furthermore, a SNP analysis allowed inferring population structure and the distribution of genetic variation. Using sequence information, the transcripts were annotated using a comparative genomics approach. In total, ~33% of 32903 transcripts were differentially expressed between populations. Among 10280 differentially expressed transcripts, 5209 transcripts deviated from neutral expectations and were likely involved in local adaptation. The population divergence at the sequence level was higher than at the gene expression level by several orders of magnitude and revealed very distinct clusters according to population origin. Our analysis revealed the respective roles of genetic drift and selection in the four Daphnia populations. This study is a first attempt to understand the genetic background of adaptation to environmental changes in a key species of aquatic ecosystems in absence of any laboratory induced stressor.
Data from: Dissecting molecular evolution in the highly diverse plant clade Caryophyllales using transcriptome sequencing
Many phylogenomic studies based on transcriptomes have been limited to "single-copy" genes due to methodological challenges in homology and orthology inferences. Only a relatively small number of studies have explored analyses beyond reconstructing species relationships. We sampled 69 transcriptomes in the hyperdiverse plant clade Caryophyllales and 27 outgroups from annotated genomes across eudicots. Using a combined similarity- and phylogenetic tree-based approach, we recovered 10,960 homolog groups, where each was represented by at least eight ingroup taxa. By decomposing these homolog trees, and taking gene duplications into account, we obtained 17,273 ortholog groups, where each was represented by at least ten ingroup taxa. We reconstructed the species phylogeny using a 1,122-gene data set with a gene occupancy of 92.1%. From the homolog trees, we found that both synonymous and nonsynonymous substitution rates in herbaceous lineages are up to three times as fast as in their woody relatives. This is the first time such a pattern has been shown across thousands of nuclear genes with dense taxon sampling. We also pinpointed regions of the Caryophyllales tree that were characterized by relatively high frequencies of gene duplication, including three previously unrecognized whole-genome duplications. By further combining information from homolog tree topology and synonymous distance between paralog pairs, phylogenetic locations for 13 putative genome duplication events were identified. Genes that experienced the greatest gene family expansion were concentrated among those involved in signal transduction and oxidoreduction, including a cytochrome P450 gene that encodes a key enzyme in the betalain synthesis pathway. Our approach demonstrates a new approach for functional phylogenomic analysis in nonmodel species that is based on homolog groups in addition to inferred ortholog groups.
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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.