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Transposable elements (TEs) play powerful and varied evolutionary and functional roles, and are widespread in most eukaryotic genomes. Research into their unique biology has driven the creation of a large collection of databases, software, classification systems, and annotation guidelines. The diversity of available TE-related methods and resources raises compatibility concerns and can be overwhelming to researchers and communicators seeking straightforward guidance or materials. To address these challenges, we have initiated a new resource, TE Hub, that provides a space where members of the TE community can collaborate to document and create resources and methods. The space consists of (1) a website organized with an open wiki framework, https://tehub.org, (2) a conversation framework via a Twitter account and a Slack channel, and (3) bi-monthly Hub Update video chats on the platform’s development. In addition to serving as a centralized repository and communication platform, TE Hub lays the foundation for improved integration, standardization, and effectiveness of diverse tools and protocols. We invite the TE community, both novices and experts in TE identification and analysis, to join us in expanding our community-oriented resource.

While several studies in a diverse set of species have shed light on the genes underlying adaptation, our knowledge on the selective pressures that explain the observed patterns lags behind. Drosophila melanogaster is a valuable organism to study environmental adaptation because this species originated in Southern Africa and has recently expanded worldwide, and also because it has a functionally well-annotated genome. In this study, we aimed to decipher which environmental variables are relevant for adaptation of D. melanogaster natural populations in Europe and North America. We analysed 36 whole-genome pool-seq samples of D. melanogaster natural populations collected in 20 European and 11 North American locations. We used the BayPass software to identify single nucleotide polymorphisms (SNPs) and transposable elements (TEs) showing signature of adaptive differentiation across populations, as well as significant associations with 59 environmental variables related to temperature, rainfall, evaporation, solar radiation, wind, daylight hours, and soil type. We found that in addition to temperature and rainfall, wind related variables are also relevant for D. melanogaster environmental adaptation. Interestingly, 23%–51% of the genes that showed significant associations with environmental variables were not found overly differentiated across populations. In addition to SNPs, we also identified 10 reference transposable element insertions associated with environmental variables. Our results showed that genome-environment association analysis can identify adaptive genetic variants that are undetected by population differentiation analysis while also allowing the identification of candidate environmental drivers of adaptation., We acknowledge the support from the European Drosophila Population Genomics Consortium (DrosEU), which is funded by a Special Topics Network (STN) grant from the European Society of Evolutionary Biology (ESEB). We also thank Thomas Flatt for comments on the manuscript. This project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (H2020-ERC-2014-CoG-647900).

Drosophila melanogaster is an important model for antiviral immunity in arthropods, but very few DNA viruses have been described from the family Drosophilidae. This deficiency limits our opportunity to use natural host-pathogen combinations in experimental studies, and may bias our understanding of the Drosophila virome. Here, we report fourteen DNA viruses detected in a metagenomic analysis of 6668 pool-sequenced Drosophila, sampled from forty-seven European locations between 2014 and 2016. These include three new nudiviruses, a new and divergent entomopoxvirus, a virus related to Leptopilina boulardi filamentous virus, and a virus related to Musca domestica salivary gland hypertrophy virus. We also find an endogenous genomic copy of galbut virus, a double-stranded RNA partitivirus, segregating at very low frequency. Remarkably, we find that Drosophila Vesanto virus, a small DNA virus previously described as a bidnavirus, may be composed of up to twelve segments and thus represent a new lineage of segmented DNA viruses. Two of the DNA viruses, Drosophila Kallithea nudivirus and Drosophila Vesanto virus are relatively common, found in 2 per cent or more of wild flies. The others are rare, with many likely to be represented by a single infected fly. We find that virus prevalence in Europe reflects the prevalence seen in publicly available datasets, with Drosophila Kallithea nudivirus and Drosophila Vesanto virus the only ones commonly detectable in public data from wild-caught flies and large population cages, and the other viruses being rare or absent. These analyses suggest that DNA viruses are at lower prevalence than RNA viruses in D.melanogaster, and may be less likely to persist in laboratory cultures. Our findings go some way to redressing an earlier bias toward RNA virus studies in Drosophila, and lay the foundation needed to harness the power of Drosophila as a model system for the study of DNA viruses., M.W. was supported by the UK Natural Environmental Research Council through the E3 doctoral training programme (NE/L002558/1), and S.R. was supported by Wellcome Trust PhD programme (108905/Z/15/Z). A.B. received funding from BBSRC (grant number BB/P00685X/1). T.F. received funding from Swiss National Science Foundation (grant numbers 31003A-182262, PP00P3_165836, and PP00P3_133641/1). C.G. received funding from Agence Nationale de la Recherche (grant number ANR-15-CE32-0011-01). J.G. received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (H2020-ERC-2014-CoG-647900) and from the Fundación Española para la Ciencia y la Tecnologia-Ministerio de Economía y Competitividad (FCT-15-10187). S.G. received funding from Deutsche Forschungsgemeinschaft (grant number GR 4495/2). M.K. received funding from Academy of Finland projects (268214 and 322980). M.K. received funding from Austrian Science Fund (FWF; grant number P32275). V.L. received funding from Danish Research council for natural Sciences (FNU; grant number 4002-00113B). B.S.O. received funding from the Scientific and Technological Research Council of Turkey (TUBITAK; grant number 214Z238). J.P. received funding from Deutsche Forschungsgemeinschaft (grant number PA 903/8). M.S.-R., M.S.V., and M.J. received funding from the Ministry of Education, Science and Technological Development of the Republic of Serbia (grant number 451-03-68/2020-14/200178). F.S. received funding from Deutsche Forschungsgemeinschaft (grant number STA1154/4-1; Projektnummer 408908608). M.T., A.P., and K.E. received funding from the Ministry of Education, Science and Technological Development of the Republic of Serbia (grant number 451-03-68/2020-14/200007). The DrosEU consortium has been funded by a Special Topics Network (STN) grant by the European Society of Evolutionary Biology (ESEB).

Most of the current knowledge on the genetic basis of adaptive evolution is based on the analysis of single nucleotide polymorphisms (SNPs). Despite increasing evidence for their causal role, the contribution of structural variants to adaptive evolution remains largely unexplored. In this work, we analyzed the population frequencies of 1,615 Transposable Element (TE) insertions annotated in the reference genome of Drosophila melanogaster, in 91 samples from 60 worldwide natural populations. We identified a set of 300 polymorphic TEs that are present at high population frequencies, and located in genomic regions with high recombination rate, where the efficiency of natural selection is high. The age and the length of these 300 TEs are consistent with relatively young and long insertions reaching high frequencies due to the action of positive selection. Besides, we identified a set of 21 fixed TEs also likely to be adaptive. Indeed, we, and others, found evidence of selection for 84 of these reference TE insertions. The analysis of the genes located nearby these 84 candidate adaptive insertions suggested that the functional response to selection is related with the GO categories of response to stimulus, behavior, and development. We further showed that a subset of the candidate adaptive TEs affects expression of nearby genes, and five of them have already been linked to an ecologically relevant phenotypic effect. Our results provide a more complete understanding of the genetic variation and the fitness-related traits relevant for adaptive evolution. Similar studies should help uncover the importance of TE-induced adaptive mutations in other species as well., Author summary Transposable elements are fragments of genomic DNA that have the ability to move around the genome by creating new copies of themselves. Although there is evidence suggesting that transposable elements play important roles in genome function and genome evolution, our current understanding is based on the analysis of a subset of all transposable element insertions present in the genome, in only a few natural populations. Advances in genome sequencing and bioinformatics tools allow us now to investigate all transposable element insertions in genomes across continents. In this work, we analyzed the age, size, and frequency of 1,615 transposable elements in 91 samples from 60 worldwide natural populations of the model species Drosophila melanogaster. The genomic regions surrounding 84 transposable elements indicate that they could have an adaptive effect for the flies that carry them. These insertions are located nearby genes involved in stress response, behavior and development suggesting that these biological processes are affected by transposable element insertions.