Browsing by Subject "phylogenomics"

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  • Guo, Baocheng; Fang, Bohao; Shikano, Takahito; Momigliano, Paolo; Wang, Cui; Kravchenko, Alexandra; Merilä, Juha (2019)
    Hybridization and convergent evolution are phenomena of broad interest in evolutionary biology, but their occurrence poses challenges for reconstructing evolutionary affinities among affected taxa. Sticklebacks in the genus Pungitius are a case in point: evolutionary relationships and taxonomic validity of different species and populations in this circumpolarly distributed species complex remain contentious due to convergent evolution of traits regarded as diagnostic in their taxonomy, and possibly also due to frequent hybridization among taxa. To clarify the evolutionary relationships among different Pungitius species and populations globally, as well as to study the prevalence and extent of introgression among recognized species, genomic data sets of both reference genome-anchored single nucleotide polymorphisms and de novo assembled RAD-tag loci were constructed with RAD-seq data. Both data sets yielded topologically identical and well-supported species trees. Incongruence between nuclear and mitochondrial DNA-based trees was found and suggested possibly frequent hybridization and mitogenome capture during the evolution of Pungitius sticklebacks. Further analyses revealed evidence for frequent nuclear genetic introgression among Pungitius species, although the estimated proportions of autosomal introgression were low. Apart from providing evidence for frequent hybridization, the results challenge earlier mitochondrial and morphology-based hypotheses regarding the number of species and their affinities in this genus: at least seven extant species can be recognized on the basis of genetic data. The results also shed new light on the biogeographical history of the Pungitius-complex, including suggestion of several trans-Arctic invasions of Europe from the Northern Pacific. The well-resolved phylogeny should facilitate the utility of this genus as a model system for future comparative evolutionary studies.
  • Barylski, Jacub; Enault, François; Dutilh, Bas E.; Schuller, Margo B.P.; Edwards, Robert A.; Gillis, Annika; Klumpp, Jochen; Knezevic, Petar; Krupovic, Mart; Kuhn, Jens H.; Lavigne, Rob; Oksanen, Hanna M; Sullivan, Matthew B.; Jang, Ho Bin; Simmonds, Peter; Aiewsakun, Pakorn; Wittmann, Johannes; Tolstoy, Igor; Brister, J. Rodney; Kropinki, Andrew; Adriaenssens, Evelien M. (2020)
    Tailed bacteriophages are the most abundant and diverse viruses in the world, with genome sizes ranging from 10 kbp to over 500 kbp. Yet, due to historical reasons, all this diversity is confined to a single virus order-Caudovirales, composed of just four families: Myoviridae, Siphoviridae, Podoviridae, and the newly created Ackermannviridae family. In recent years, this morphology-based classification scheme has started to crumble under the constant flood of phage sequences, revealing that tailed phages are even more genetically diverse than once thought. This prompted us, the Bacterial and Archaeal Viruses Subcommittee of the International Committee on Taxonomy of Viruses (ICTV), to consider overall reorganization of phage taxonomy. In this study, we used a wide range of complementary methods-including comparative genomics, core genome analysis, and marker gene phylogenetics-to show that the group of Bacillus phage SPO1-related viruses previously classified into the Spounavirinae subfamily, is clearly distinct from other members of the family Myoviridae and its diversity deserves the rank of an autonomous family. Thus, we removed this group from the Myoviridae family and created the family Herelleviridae-a new taxon of the same rank. In the process of the taxon evaluation, we explored the feasibility of different demarcation criteria and critically evaluated the usefulness of our methods for phage classification. The convergence of results, drawing a consistent and comprehensive picture of a new family with associated subfamilies, regardless of method, demonstrates that the tools applied here are particularly useful in phage taxonomy. We are convinced that creation of this novel family is a crucial milestone toward much-needed reclassification in the Caudovirales order.
  • Mehmood, Furrukh; Abdullah,; Ubaid, Zartasha; Bao, Yiming; Poczai, Péter; Mirza, Bushra (2020)
    Within the family Solanaceae, Withania is a small genus belonging to the Solanoideae subfamily. Here, we report the de novo assembled chloroplast genome sequences of W. coagulans, W. adpressa, and W. riebeckii. The length of these genomes ranged from 154,162 to 154,364 base pairs (bp). These genomes contained a pair of inverted repeats (IRa and IRb) ranging from 25,029 to 25,071 bp that were separated by a large single-copy (LSC) region of 85,635-85,765 bp and a small single-copy (SSC) region of 18,457-18,469 bp. We analyzed the structural organization, gene content and order, guanine-cytosine content, codon usage, RNA-editing sites, microsatellites, oligonucleotide and tandem repeats, and substitutions of Withania plastomes, which revealed high similarities among the species. Comparative analysis among the Withania species also highlighted 10 divergent hotspots that could potentially be used for molecular marker development, phylogenetic analysis, and species identification. Furthermore, our analyses showed that even three mutational hotspots (rps4-trnT, trnM-atpE, and rps15) were sufficient to discriminate the Withania species included in current study.
  • Poczai, Péter; Amiryousefi, Ali; Hyvönen, Jaakko (2017)
    In this study, we announce the complete chloroplast genome sequence of Nicotiana attenuata. The genome sequence of 155,941 bp consists of two inverted repeat (IRa and IRb) regions of 25,438 bp each, a large single-copy (LSC) region of 86,513 bp and a small single-copy (SSC) region of 18,524 bp. The overall GC content is 37.9% and the GC contents of LSC, IRs, and SSC are 36%, 43.2%, and 32.1%, respectively. The plastome with 129 annotated unique genes includes 84 protein-coding genes, 37 tRNA genes, and 8 rRNA genes. Using the whole chloroplast genome sequences alignment of 16 Solanaceae species a phylogenetic hypothesis is presented validating the position of N. attenuata within Nicotianeae.
  • Fang, Bohao; Merilä, Juha; Matschiner, Michael; Momigliano, Paolo (2020)
    Incomplete lineage sorting (ILS) can lead to biased divergence time estimates. To explore if and how ILS has influenced the results of a recent study of worldwide phylogeny of three-spined sticklebacks (Gasterosteus aculeatus), we estimated divergence times among major clades by applying both a concatenation approach and the multispecies coalescent (MSC) model to single-nucleotide polymorphisms. To further test the influence of different calibration strategies, we applied different calibrations to the root and to younger nodes in addition to the ones used in the previous study. Both the updated calibrations and the application of the MSC model influenced divergence time estimates, sometimes significantly. The new divergence time estimates were more ancient than in the previous study for older nodes, whereas the estimates of younger nodes were not strongly affected by the re-analyses. However, given the applied MSC method employs a simple substitution model and cannot account for changes in population size, we suggest that different analytical approaches and calibration strategies should be used in order to explore uncertainty in divergence time estimates. This study provides a valuable reference timeline for the ages of worldwide three-spined stickleback populations and emphasizes the need to embrace, rather than obscure, uncertainties around divergence time estimates.
  • Castro, H.; Jaakkonen, A.; Hakakorpi, A.; Hakkinen, M.; Isidro, J.; Korkeala, H.; Lindström, M.; Hallanvuo, S. (2019)
    Frontiers in Microbiology Vol. 14, No. 10, p. 1049.
    Packaged raw milk contaminated with Yersinia pseudotuberculosis mediated a large yersiniosis outbreak in southern Finland in 2014. The outbreak was traced back to a single dairy farm in southern Finland. Here we explore risk factors leading to the outbreak through epidemiologic investigation of the outbreak farm and through genomic and phenotypic characterization of the farm’s outbreak and non-outbreak associated Y. pseudotuberculosis strains. We show that the outbreak strain persisted on the farm throughout the 7-month study, whereas the non-outbreak strains occurred sporadically. Phylogenomic analysis illustrated that the outbreak strain was related to previously published genomes of wild animal isolates from Finland, implying that wild animals were a potential source of the outbreak strain to the farm. We observed allelic differences between the farm’s outbreak and non-outbreak strains in several genes associated with virulence, stress response and biofilm formation, and found that the outbreak strain formed biofilm in vitro and maintained better growth fitness during cold stress than the non-outbreak strains. Finally, we demonstrate the rapid growth of the outbreak strain in packaged raw milk during refrigerated storage. This study provides insight of the risk factors leading to the Y. pseudotuberculosis outbreak, highlights the importance of pest control to avoid the spread of pathogens from wild to domestic animals, and demonstrates that the cold chain is insufficient as the sole risk management strategy to control Y. pseudotuberculosis risk associated with raw drinking milk.
  • Castro, Hanna; Jaakkonen, Anniina; Hakakorpi, Anna; Hakkinen, Marjaana; Isidro, Joana; Korkeala, Hannu; Lindström, Miia; Hallanvuo, Saija (2019)
    Packaged raw milk contaminated with Yersinia pseudotuberculosis mediated a large yersiniosis outbreak in southern Finland in 2014. The outbreak was traced back to a single dairy farm in southern Finland. Here we explore risk factors leading to the outbreak through epidemiologic investigation of the outbreak farm and through genomic and phenotypic characterization of the farm's outbreak and non-outbreak associated Y. pseudotuberculosis strains. We show that the outbreak strain persisted on the farm throughout the 7-month study, whereas the non-outbreak strains occurred sporadically. Phylogenomic analysis illustrated that the outbreak strain was related to previously published genomes of wild animal isolates from Finland, implying that wild animals were a potential source of the outbreak strain to the farm. We observed allelic differences between the farm's outbreak and non-outbreak strains in several genes associated with virulence, stress response and biofilm formation, and found that the outbreak strain formed biofilm in vitro and maintained better growth fitness during cold stress than the non-outbreak strains. Finally, we demonstrate the rapid growth of the outbreak strain in packaged raw milk during refrigerated storage. This study provides insight of the risk factors leading to the Y. pseudotuberculosis outbreak, highlights the importance of pest control to avoid the spread of pathogens from wild to domestic animals, and demonstrates that the cold chain is insufficient as the sole risk management strategy to control Y. pseudotuberculosis risk associated with raw drinking milk.
  • Osterholm, Julia; Popin, Rafael V.; Fewer, David P.; Sivonen, Kaarina (2020)
    Cyanobacteria produce an array of toxins that pose serious health risks to humans and animals. The closely related diazotrophic genera, Anabaena, Dolichospermum and Aphanizomenon, frequently form poisonous blooms in lakes and brackish waters around the world. These genera form a complex now termed the Anabaena, Dolichospermum and Aphanizomenon (ADA) clade and produce a greater array of toxins than any other cyanobacteria group. However, taxonomic confusion masks the distribution of toxin biosynthetic pathways in cyanobacteria. Here we obtained 11 new draft genomes to improve the understanding of toxin production in these genera. Comparison of secondary metabolite pathways in all available 31 genomes for these three genera suggests that the ability to produce microcystin, anatoxin-a, and saxitoxin is associated with specific subgroups. Each toxin gene cluster was concentrated or even limited to a certain subgroup within the ADA clade. Our results indicate that members of the ADA clade encode a variety of secondary metabolites following the phylogenetic clustering of constituent species. The newly sequenced members of the ADA clade show that phylogenetic separation of planktonic Dolichospermum and benthic Anabaena is not complete. This underscores the importance of taxonomic revision of Anabaena, Dolichospermum and Aphanizomenon genera to reflect current phylogenomic understanding.
  • Jike, Wuhe; Li, Mingai; Zadra, Nicola; Barbaro, Enrico; Sablok, Gaurav; Bertorelle, Giorgio; Rota-Stabelli, Omar; Varotto, Claudio (2020)
    Polyploidization is a frequent phenomenon in plants, which entails the increase from one generation to the next by multiples of the haploid number of chromosomes. While tetraploidization is arguably the most common and stable outcome of polyploidization, over evolutionary time triploids often constitute only a transient phase, or a "triploid bridge", between diploid and tetraploid levels. In this study, we reconstructed in a robust phylogenomic and statistical framework the evolutionary history of polyploidization inArundo, a small genus from the Poaceae family with promising biomass, bioenergy and phytoremediation species. Through the obtainment of 10 novel leaf transcriptomes forArundoand outgroup species, our results prove that recurrent demiduplication has likely been a major driver of evolution in this species-poor genus. Molecular dating further demonstrates that the species originating by demiduplication stalled in the "triploid bridge" for evolutionary times in the order of millions of years without undergoing tetratploidization. Nevertheless, we found signatures of molecular evolution highlighting some of the processes that accompanied the genus radiation. Our results clarify the complex nature ofArundoevolution and are valuable for future gene functional validation as well as reverse and comparative genomics efforts in theArundogenus and other Arundinoideae.
  • de Been, Mark; van Schaik, Willem; Cheng, Lu; Corander, Jukka; Willems, Rob J. (2013)
  • Aubriot, Xavier; Knapp, Sandra; Syfert, Mindy; Poczai, Péter; Buerki, Sven (2018)
    • While brinjal eggplant (Solanum melongena L.) is the second most important solanaceaous vegetable crop, we lack firm knowledge of its evolutionary relationships. This in turn limits efficient use of crop wild relatives in eggplant improvement. Here, we examine the hypothesis of linear step-wise expansion of the eggplant group from Africa to Asia. • We use museum collections to generate nuclear and full-plastome data for all species of the eggplant clade. We combine a phylogenomic approach with distribution data to infer a biogeographic scenario for the clade. • The eggplant clade has Pleistocene origins in northern Africa. Dispersions to tropical Asia gave rise to Solanum insanum, the wild progenitor of the eggplant, and to Africa distinct lineages of widespread and southern-African species. Results suggest that spread of species to southern Africa is recent and was likely facilitated by large mammal herbivores feeding on Solanum fruits (African elephant, impala). • Rather than a linear ‘Out Of Africa’ sequence, our results are more consistent with an initial event into Asia, and subsequent wide dispersion and differentiation across Africa driven by large mammalian herbivores. Our evolutionary results will impact future work on eggplant domestication and use of wild relatives in breeding of this increasingly important solanaceous crop.
  • Amiryousefi, Ali; Hyvönen, Jaakko; Poczai, Péter (2017)
  • Amiryousefi, Ali; Hyvönen, Jaakko; Poczai, Péter (2017)