scholarly journals Divergence-Based Introgression Polarization

2020 ◽  
Vol 12 (4) ◽  
pp. 463-478 ◽  
Author(s):  
Evan S Forsythe ◽  
Daniel B Sloan ◽  
Mark A Beilstein
Keyword(s):  
Genetic Material ◽  
Introgressive Hybridization ◽  
Sequence Divergence ◽  
Whole Genome ◽  
Major Area ◽  
Genome Data ◽  
Whole Genomes ◽  
Potential Sources ◽  
Introgression Event ◽  
Do So

Abstract Introgressive hybridization results in the transfer of genetic material between species, often with fitness implications for the recipient species. The development of statistical methods for detecting the signatures of historical introgression in whole-genome data has been a major area of focus. Although existing techniques are able to identify the taxa that exchanged genes during introgression using a four-taxon system, most methods do not explicitly distinguish which taxon served as donor and which as recipient during introgression (i.e., polarization of introgression directionality). Existing methods that do polarize introgression are often only able to do so when there is a fifth taxon available and that taxon is sister to one of the taxa involved in introgression. Here, we present divergence-based introgression polarization (DIP), a method for polarizing introgression using patterns of sequence divergence across whole genomes, which operates in a four-taxon context. Thus, DIP can be applied to infer the directionality of introgression when additional taxa are not available. We use simulations to show that DIP can polarize introgression and identify potential sources of bias in the assignment of directionality, and we apply DIP to a well-described hominin introgression event.

scholarly journals Divergence-based introgression polarization

2019 ◽  
Author(s):  
Evan S. Forsythe ◽  
Daniel B. Sloan ◽  
Mark A. Beilstein
Keyword(s):  
Statistical Methods ◽  
Genetic Material ◽  
Introgressive Hybridization ◽  
Sequence Divergence ◽  
Whole Genome ◽  
Major Area ◽  
Genome Data ◽  
Whole Genomes ◽  
Potential Sources ◽  
Do So

ABSTRACTIntrogressive hybridization results in the transfer of genetic material between species, often with fitness implications for the recipient species. The development of statistical methods for detecting the signatures of historical introgression (IG) in whole-genome data has been a major area of focus. While existing techniques are able to identify the taxa that exchanged genes during IG using a four-taxon system, most methods do not explicitly distinguish which taxon served as donor and which as recipient during IG (i.e. polarization of IG directionality). The existing methods that do polarize IG are only able to do so when there is a fifth taxon available and that taxon is sister to one of the taxa involved in IG. Here, we present Divergence-based Introgression Polarization (DIP), a method for polarizing IG using patterns of sequence divergence across whole genomes, which operates in a four-taxon context. Thus, DIP can be applied to infer the directionality of IG when additional taxa are not available. We use simulations to show that DIP can polarize IG and identify potential sources of bias in the assignment of directionality, and we apply DIP to a well-described hominin IG event.

scholarly journals The Role of Hybridization in the Evolution and Emergence of New Fungal Plant Pathogens

2016 ◽  
Vol 106 (2) ◽  
pp. 104-112 ◽  
Author(s):  
Eva H. Stukenbrock
Keyword(s):  
Plant Pathogens ◽  
Environmental Changes ◽  
Genetic Material ◽  
Introgressive Hybridization ◽  
Agricultural Trade ◽  
Interspecific Mating ◽  
Long Distance ◽  
Genome Data ◽  
Fungal Plant Pathogens ◽  
Allopatric Species

Hybridization in fungi has recently been recognized as a major force in the generation of new fungal plant pathogens. These include the grass pathogen Zymoseptoria pseudotritici and the powdery mildew pathogen Blumeria graminis triticale of triticale. Hybridization also plays an important role in the transfer of genetic material between species. This process is termed introgressive hybridization and involves extensive backcrossing between hybrid and the parental species. Introgressive hybridization has contributed substantially to the successful spread of plant pathogens such as Ophiostoma ulmi and O. novo-ulmi, the causal agents of Dutch elm disease, and other tree pathogens such as the rust pathogen Melampsora. Hybridization occurs more readily between species that have previously not coexisted, so-called allopatric species. Reproductive barriers between allopatric species are likely to be more permissive allowing interspecific mating to occur. The bringing together of allopatric species of plant pathogens by global agricultural trade consequently increases the potential for hybridization between pathogen species. In light of global environmental changes, agricultural development, and the facilitated long-distance spread of fungal plant pathogens, hybridization should be considered an important mechanism whereby new pathogens may emerge. Recent studies have gained insight into the genetics and biology of fungal hybrids. Here I summarize current knowledge about hybrid speciation and introgressive hybridization. I propose that future studies will benefit greatly from the availability of large genome data sets and that genome data provide a powerful resource in combination with experimental approaches for analyses of hybrid species.

scholarly journals Structural characterization and duplication modes of pseudogenes in plants

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Flavia Mascagni ◽  
Gabriele Usai ◽  
Andrea Cavallini ◽  
Andrea Porceddu
Keyword(s):  
Evolutionary Rate ◽  
Populus Trichocarpa ◽  
Sequence Divergence ◽  
Strand Break ◽  
Whole Genome ◽  
Flanking Sequence ◽  
Plant Genomes ◽  
High Sequence Divergence ◽  
Flanking Regions

AbstractWe identified and characterized the pseudogene complements of five plant species: four dicots (Arabidopsis thaliana, Vitis vinifera, Populus trichocarpa and Phaseolus vulgaris) and one monocot (Oryza sativa). Retroposition was considered of modest importance for pseudogene formation in all investigated species except V. vinifera, which showed an unusually high number of retro-pseudogenes in non coding genic regions. By using a pipeline for the classification of sequence duplicates in plant genomes, we compared the relative importance of whole genome, tandem, proximal, transposed and dispersed duplication modes in the pseudo and functional gene complements. Pseudogenes showed higher tendencies than functional genes to genomic dispersion. Dispersed pseudogenes were prevalently fragmented and showed high sequence divergence at flanking regions. On the contrary, those deriving from whole genome duplication were proportionally less than expected based on observations on functional loci and showed higher levels of flanking sequence conservation than dispersed pseudogenes. Pseudogenes deriving from tandem and proximal duplications were in excess compared to functional loci, probably reflecting the high evolutionary rate associated with these duplication modes in plant genomes. These data are compatible with high rates of sequence turnover at neutral sites and double strand break repairs mediated duplication mechanisms.

scholarly journals Fast genetic mapping using insertion-deletion polymorphisms in Caenorhabditis elegans

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ho-Yon Hwang ◽  
Jiou Wang
Keyword(s):  
Caenorhabditis Elegans ◽  
Genetic Mapping ◽  
Whole Genome Sequencing ◽  
Genome Sequencing ◽  
Genetic Material ◽  
Mapping Method ◽  
Forward Genetics ◽  
Whole Genome ◽  
Nucleotide Polymorphisms ◽  
Large Populations

AbstractGenetic mapping is used in forward genetics to narrow the list of candidate mutations and genes corresponding to the mutant phenotype of interest. Even with modern advances in biology such as efficient identification of candidate mutations by whole-genome sequencing, mapping remains critical in pinpointing the responsible mutation. Here we describe a simple, fast, and affordable mapping toolkit that is particularly suitable for mapping in Caenorhabditis elegans. This mapping method uses insertion-deletion polymorphisms or indels that could be easily detected instead of single nucleotide polymorphisms in commonly used Hawaiian CB4856 mapping strain. The materials and methods were optimized so that mapping could be performed using tiny amount of genetic material without growing many large populations of mutants for DNA purification. We performed mapping of previously known and unknown mutations to show strengths and weaknesses of this method and to present examples of completed mapping. For situations where Hawaiian CB4856 is unsuitable, we provide an annotated list of indels as a basis for fast and easy mapping using other wild isolates. Finally, we provide rationale for using this mapping method over other alternatives as a part of a comprehensive strategy also involving whole-genome sequencing and other methods.

Extracting a needle from a haystack: reanalysis of whole genome data reveals a readily translatable finding

2009 ◽  
Vol 39 (8) ◽  
pp. 1231-1235 ◽  
Author(s):  
R. Keers ◽  
A. E. Farmer ◽  
K. J. Aitchison
Keyword(s):  
Bipolar Disorder ◽  
Calcium Channel ◽  
Unmet Need ◽  
Whole Genome ◽  
Nucleotide Polymorphisms ◽  
Gene Encoding ◽  
Genome Data ◽  
Early Results ◽  
Genome Association ◽  
Genome Study

There is significant unmet need for more effective treatments for bipolar disorder. The drug discovery process is becoming prohibitively expensive. Hence, biomarker clues to assist or shortcut this process are now widely sought. Using the publicly available data from the whole genome association study conducted by the Wellcome Trust Case Control Consortium, we sought to identify groups of genetic markers (single nucleotide polymorphisms) in which each marker was independently associated with bipolar disorder, with a less stringent threshold than that set by the original investigators (p⩽1×10−4). We identified a group of markers occurring within the CACNA1C gene (encoding the alpha subunit of the calcium channel Cav1.2). We then ascertained that this locus had been previously associated with the disorder in both a smaller and a whole genome study, and that a number of drugs blocking this channel (including verapamil and diltiazem) had been trialled in the treatment of bipolar disorder. The dihydropyridine-based blockers such as nimodipine that bind specifically to Cav1.2 and are more penetrant to the central nervous system have shown some promising early results; however, further trials are indicated. In addition, migraine is commonly seen in affective disorder, and calcium channel antagonists are successfully used in the treatment of migraine. One such agent, flunarizine, is structurally related to other first-generation derivatives of antihistamines such as antipsychotics. This implies that flunarizine could be useful in the treatment of bipolar disorder, and, furthermore, that other currently licensed drugs should be investigated for antagonism of Cav1.2.

scholarly journals DNA Extraction and Host Depletion Methods Significantly Impact and Potentially Bias Bacterial Detection in a Biological Fluid

mSystems ◽  
2021 ◽  
Author(s):  
Erika Ganda ◽  
Kristen L. Beck ◽  
Niina Haiminen ◽  
Justin D. Silverman ◽  
Ban Kawas ◽  
...  
Keyword(s):  
Food Safety ◽  
Dna Extraction ◽  
Bacterial Communities ◽  
Biological Fluid ◽  
Genetic Material ◽  
Next Generation ◽  
Microbial Composition ◽  
Chemical Methods ◽  
Bacterial Detection ◽  
Do So

Tracking the bacterial communities present in our food has the potential to inform food safety and product origin. To do so, the entire genetic material present in a sample is extracted using chemical methods or commercially available kits and sequenced using next-generation platforms to provide a snapshot of the microbial composition.

scholarly journals Population Genomic- and Phylogenomic-Enabled Advances to Increase Insight Into Pathogen Biology and Epidemiology

2021 ◽  
Vol 111 (1) ◽  
pp. 8-11
Author(s):  
Remco Stam ◽  
Pierre Gladieux ◽  
Boris A. Vinatzer ◽  
Erica M. Goss ◽  
Neha Potnis ◽  
...  
Keyword(s):  
Population Genetics ◽  
Population Genomics ◽  
Cost Effective ◽  
Whole Genome ◽  
Genome Data ◽  
Sequencing Technologies ◽  
Population Genomic ◽  
High Throughput Dna Sequencing ◽  
Opening Up ◽  
Insight Into

Population genetics has been a key discipline in phytopathology for many years. The recent rise in cost-effective, high-throughput DNA sequencing technologies, allows sequencing of dozens, if not hundreds of specimens, turning population genetics into population genomics and opening up new, exciting opportunities as described in this Focus Issue . Without the limitations of genetic markers and the availability of whole or near whole-genome data, population genomics can give new insights into the biology, evolution and adaptation, and dissemination patterns of plant-associated microbes.

scholarly journals Urine as a high-quality source of host genomic DNA from wild populations

2020 ◽  
Author(s):  
Andrew T. Ozga ◽  
Timothy H. Webster ◽  
Ian C. Gilby ◽  
Melissa A. Wilson ◽  
Rebecca S. Nockerts ◽  
...  
Keyword(s):  
Genetic Material ◽  
Population History ◽  
Whole Genome ◽  
Dental Calculus ◽  
Wild Populations ◽  
Multiple Sources ◽  
Allelic Dropout ◽  
Natural Habitats ◽  
High Quality ◽  
Animal Populations

AbstractThe ability to generate genomic data from wild animal populations has the potential to give unprecedented insight into the population history and dynamics of species in their natural habitats. However, in the case of many species, it is impossible legally, ethically, or logistically to obtain tissues samples of high-quality necessary for genomic analyses. In this study we evaluate the success of multiple sources of genetic material (feces, urine, dentin, and dental calculus) and several capture methods (shotgun, whole-genome, exome) in generating genome-scale data in wild eastern chimpanzees (Pan troglodytes schweinfurthii) from Gombe National Park, Tanzania. We found that urine harbors significantly more host DNA than other sources, leading to broader and deeper coverage across the genome. Urine also exhibited a lower rate of allelic dropout. We found exome sequencing to be far more successful than both shotgun sequencing and whole-genome capture at generating usable data from low-quality samples such as feces and dental calculus. These results highlight urine as a promising and untapped source of DNA that can be noninvasively collected from wild populations of many species.

scholarly journals High Resolution Ancestry Deconvolution for Next Generation Genomic Data

2021 ◽  
Author(s):  
Helgi Hilmarsson ◽  
Arvind S. Kumar ◽  
Richa Rastogi ◽  
Carlos D. Bustamante ◽  
Daniel Mas Montserrat ◽  
...  
Keyword(s):  
High Resolution ◽  
Prediction Models ◽  
Association Studies ◽  
Training Data ◽  
Genome Wide Association Studies ◽  
Whole Genome ◽  
Next Generation ◽  
Genome Data ◽  
Computational Performance ◽  
Genetic Risk Prediction

ABSTRACTAs genome-wide association studies and genetic risk prediction models are extended to globally diverse and admixed cohorts, ancestry deconvolution has become an increasingly important tool. Also known as local ancestry inference (LAI), this technique identifies the ancestry of each region of an individual’s genome, thus permitting downstream analyses to account for genetic effects that vary between ancestries. Since existing LAI methods were developed before the rise of massive, whole genome biobanks, they are computationally burdened by these large next generation datasets. Current LAI algorithms also fail to harness the potential of whole genome sequences, falling well short of the accuracy that such high variant densities can enable. Here we introduce Gnomix, a set of algorithms that address each of these points, achieving higher accuracy and swifter computational performance than any existing LAI method, while also enabling portable models that are particularly useful when training data are not shareable due to privacy or other restrictions. We demonstrate Gnomix (and its swift phase correction counterpart Gnofix) on worldwide whole-genome data from both humans and canids and utilize its high resolution accuracy to identify the location of ancient New World haplotypes in the Xoloitzcuintle, dating back over 100 generations. Code is available at https://github.com/AI-sandbox/gnomix.

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