scholarly journals Continental-scale genomic analysis suggests shared post-admixture adaptation in Americas

2020 ◽  
Author(s):  
Linda Ongaro ◽  
Mayukh Mondal ◽  
Rodrigo Flores ◽  
Davide Marnetto ◽  
Ludovica Molinaro ◽  
...  
Keyword(s):  
Natural Selection ◽  
Native Americans ◽  
Genomic Analysis ◽  
Human Leukocyte ◽  
System Response ◽  
Continental Scale ◽  
Genome Wide ◽  
Genome Wide Data ◽  
Human Leukocyte Antigen Locus ◽  
Genomic Regions

AbstractAmerican populations are one of the most interesting examples of recently admixed groups, where ancestral components from three major continental human groups (Africans, Eurasians and Native Americans) have admixed within the last 15 generations. Recently, several genetic surveys focusing on thousands of individuals shed light on the geography, chronology and relevance of these events. However, despite the fact that gene-flow could drive adaptive evolution, it is not clear whether and how natural selection acted on the resulting genetic variation in the Americas.In this study, we analysed the patterns of local ancestry of genomic fragments in genome-wide data for ∼6,000 admixed individuals from ten American countries. In doing so, we identified regions characterized by a Divergent Ancestry Profile (DAP), in which a significant over or under ancestral representation is evident.Our results highlighted a series of genomic regions with Divergent Ancestry Profiles (DAP) associated with immune system response and relevant medical traits, with the longest DAP region encompassing the Human Leukocyte Antigen locus. Furthermore, we found that DAP regions are enriched in genes linked to cancer-related traits and autoimmune diseases. Then, analyzing the biological impact of these regions, we showed that natural selection could have acted preferentially towards variants located in coding and non-coding transcripts, and characterized by a high deleteriousness score.Taken together, our analyses suggest that shared patterns of post admixture adaptation occurred at continental scale in the Americas, affecting more often functional and impactful genomic variants.

scholarly journals Comparative Genomic Analysis Confirms Five Genetic Populations of the Select Agent, Rathayibacter toxicus

2020 ◽  
Vol 8 (3) ◽  
pp. 366
Author(s):  
Jarred Yasuhara-Bell ◽  
Mohammad Arif ◽  
Grethel Y. Busot ◽  
Rachel Mann ◽  
Brendan Rodoni ◽  
...  
Keyword(s):  
Genomic Analysis ◽  
The United States ◽  
Grass Species ◽  
Comparative Genomic ◽  
Underrepresented Populations ◽  
System A ◽  
Genome Wide ◽  
The Family ◽  
Study Support ◽  
Genomic Regions

Rathayibacter toxicus is a Gram-positive, nematode-vectored bacterium that infects several grass species in the family Poaceae. Unique in its genus, R. toxicus has the smallest genome, possesses a complete CRISPR-Cas system, a vancomycin-resistance cassette, produces tunicamycin, a corynetoxin responsible for livestock deaths in Australia, and is designated a Select Agent in the United States. In-depth, genome-wide analyses performed in this study support the previously designated five genetic populations, with a core genome comprising approximately 80% of the genome for all populations. Results varied as a function of the type of analysis and when using different bioinformatics tools for the same analysis; e.g., some programs failed to identify specific genomic regions that were actually present. The software variance highlights the need to verify bioinformatics results by additional methods; e.g., PCR, mapping genes to genomes, use of multiple algorithms). These analyses suggest the following relationships among populations: RT-IV ↔ RT-I ↔ RT-II ↔ RT-III ↔ RT-V, with RT-IV and RT-V being the most unrelated. This is the most comprehensive analysis of R. toxicus that included populations RT-I and RT-V. Future studies require underrepresented populations and more recent isolates from varied hosts and geographic locations.

scholarly journals Genomic response to natural selection within alpine cattle breeds

2018 ◽  
Vol 63 (No. 4) ◽  
pp. 136-143
Author(s):  
N. Moravčíková ◽  
M. Simčič ◽  
G. Mészáros ◽  
J. Sölkner ◽  
V. Kukučková ◽  
...  
Keyword(s):  
Natural Selection ◽  
Principal Component ◽  
Selection Response ◽  
Population Based ◽  
Nucleotide Polymorphisms ◽  
Data Quality Control ◽  
Cattle Breeds ◽  
Genome Wide ◽  
Genomic Regions ◽  
Genomic Response

The aim of this study was to analyse the genomic regions that have been target of natural selection with respect to identifying the loci responsible mainly for fitness traits across six alpine cattle breeds. The genome-wide scan for selection signatures was performed using genotyping data from totally 465 animals. After applying data quality control, overall 35 873 single nucleotide polymorphisms were useable for the subsequent analysis. The detection of genomic regions affected by natural selection was carried out using the approach of principal component analysis. The analysis was based on the assumption that markers extremely related to the population structure are also candidates for local adaptation potential of the population. Based on the expected false discovery rate equal to 10% up to 1138 loci were identified as outliers. The strongest signals of selection were found in genomic regions on BTA 1, 2, 3, 6, 9, 11, 13, and 22. Most genes located in the identified regions have been previously associated with immunity system as well as body growth and muscle formation that mainly reflect the pressure of both natural and artificial selection in respect to adaptation of analysed breeds to the local environmental conditions. The results also signalized that those regions represent a correlated selection response in way to maintain the fitness of analysed breeds.

scholarly journals Genome-wide scans provide evidence for positive selection of genes implicated in Lassa fever

2012 ◽  
Vol 367 (1590) ◽  
pp. 868-877 ◽  
Author(s):  
Kristian G. Andersen ◽  
Ilya Shylakhter ◽  
Shervin Tabrizi ◽  
Sharon R. Grossman ◽  
Christian T. Happi ◽  
...  
Keyword(s):  
Natural Selection ◽  
Positive Selection ◽  
Lassa Fever ◽  
West African ◽  
Lassa Virus ◽  
Genome Wide ◽  
African Populations ◽  
Genome Wide Data ◽  
Differential Gene ◽  
Selection Of

Rapidly evolving viruses and other pathogens can have an immense impact on human evolution as natural selection acts to increase the prevalence of genetic variants providing resistance to disease. With the emergence of large datasets of human genetic variation, we can search for signatures of natural selection in the human genome driven by such disease-causing microorganisms. Based on this approach, we have previously hypothesized that Lassa virus (LASV) may have been a driver of natural selection in West African populations where Lassa haemorrhagic fever is endemic. In this study, we provide further evidence for this notion. By applying tests for selection to genome-wide data from the International Haplotype Map Consortium and the 1000 Genomes Consortium, we demonstrate evidence for positive selection in LARGE and interleukin 21 ( IL21 ), two genes implicated in LASV infectivity and immunity. We further localized the signals of selection, using the recently developed composite of multiple signals method, to introns and putative regulatory regions of those genes. Our results suggest that natural selection may have targeted variants giving rise to alternative splicing or differential gene expression of LARGE and IL21 . Overall, our study supports the hypothesis that selective pressures imposed by LASV may have led to the emergence of particular alleles conferring resistance to Lassa fever, and opens up new avenues of research pursuit.

scholarly journals Genome-wide selection scans integrated with association mapping reveal mechanisms of physiological adaptation across a salinity gradient in killifish

2018 ◽  
Author(s):  
Reid S. Brennan ◽  
Timothy M. Healy ◽  
Heather J. Bryant ◽  
Man Van La ◽  
Patricia M. Schulte ◽  
...  
Keyword(s):  
Natural Selection ◽  
Salinity Tolerance ◽  
Hypoxia Tolerance ◽  
Physiological Traits ◽  
Adaptive Divergence ◽  
Genome Wide ◽  
Native Populations ◽  
Genomic Regions ◽  
Insight Into ◽  
Freshwater Environments

AbstractAdaptive divergence between marine and freshwater environments is important in generating phyletic diversity within fishes, but the genetic basis of adaptation to freshwater habitats remains poorly understood. Available approaches to detect adaptive loci include genome scans for selection, but these can be difficult to interpret because of incomplete knowledge of the connection between genotype and phenotype. In contrast, genome wide association studies (GWAS) are powerful tools for linking genotype to phenotype, but offer limited insight into the evolutionary forces shaping variation. Here, we combine GWAS and selection scans to identify loci important in the adaptation of complex physiological traits to freshwater environments. We focused on freshwater (FW)-native and brackish water (BW)-native populations of the Atlantic killifish (Fundulus heteroclitus) as well as a population that is a natural admixture of these two populations. We measured phenotypes for multiple physiological traits that differ between populations and that may contribute to adaptation across osmotic niches (salinity tolerance, hypoxia tolerance, metabolic rate, and body shape) and used a reduced representation approach for genome-wide genotyping. Our results show patterns of population divergence in physiological capabilities that are consistent with local adaptation. Selection scans between BW-native and FW-native populations identified genomic regions that presumably aect fitness between BW and FW environments, while GWAS revealed loci that contribute to variation for each physiological trait. There was substantial overlap in the genomic regions putatively under selection and loci associated with the measured physiological traits, suggesting that these phenotypes are important for adaptive divergence between BW and FW environments. Our analysis also implicates candidate genes likely involved in physiological capabilities, some of which validate a priori hypotheses. Together, these data provide insight into the mechanisms that enable diversification of fishes across osmotic boundaries.Author SummaryIdentifying the genes that underlie adaptation is important for understanding the evolutionary process, but this is technically challenging. We bring multiple lines of evidence to bear for identifying genes that underlie adaptive divergence. Specifically, we integrate genotype-phenotype association mapping with genome-wide scans for signatures of natural selection to reveal genes that underlie phenotypic variation and that are adaptive in populations of killifish that are diverging between marine and freshwater environments. Because adaptation is likely manifest in multiple physiological traits, we focus on hypoxia tolerance, salinity tolerance, and metabolic rate; traits that are divergent between marine and freshwater populations. We show that each of these phenotypes is evolving by natural selection between environments; genetic variants that contribute to variation in these physiological traits tend to be evolving by natural selection between marine and freshwater populations. Furthermore, one of our top candidate genes provides a mechanistic explanation for previous hypotheses that suggest the adaptive importance of cellular tight junctions. Together, these data demonstrate a powerful approach to identify genes involved in adaptation and help to reveal the mechanisms enabling transitions of fishes across osmotic boundaries.

scholarly journals Towards a new history and geography of human genes informed by ancient DNA

2014 ◽  
Author(s):  
Joseph Pickrell ◽  
David Reich
Keyword(s):  
Natural Selection ◽  
Ancient Dna ◽  
Population Replacement ◽  
Local Conditions ◽  
Geographic Locations ◽  
Technological Advances ◽  
Genome Wide ◽  
Human Genes ◽  
Genome Wide Data ◽  
History Of

Genetic information contains a record of the history of our species, and technological advances have transformed our ability to access this record. Many studies have used genome-wide data from populations today to learn about the peopling of the globe and subsequent adaptation to local conditions. Implicit in this research is the assumption that the geographic locations of people today are informative about the geographic locations of their ancestors in the distant past. However, it is now clear that long-range migration, admixture and population replacement have been the rule rather than the exception in human history. In light of this, we argue that it is time to critically re-evaluate current views of the peopling of the globe and the importance of natural selection in determining the geographic distribution of phenotypes. We specifically highlight the transformative potential of ancient DNA. By accessing the genetic make-up of populations living at archaeologically-known times and places, ancient DNA makes it possible to directly track migrations and responses to natural selection.

scholarly journals The genetic legacy of continental scale admixture in Indian Austroasiatic speakers

2018 ◽  
Author(s):  
Kai Tätte ◽  
Luca Pagani ◽  
Ajai K. Pathak ◽  
Sulev Kõks ◽  
Binh Ho Duy ◽  
...  
Keyword(s):  
South Asians ◽  
Asian Population ◽  
South Asian Population ◽  
Southeast Asians ◽  
Continental Scale ◽  
Genome Wide ◽  
Genome Wide Data ◽  
Different Populations ◽  
Source Populations ◽  
Austroasiatic Languages

AbstractSurrounded by speakers of Indo-European, Dravidian and Tibeto-Burman languages, around 11 million Munda (a branch of Austroasiatic language family) speakers live in the densely populated and genetically diverse South Asia. Their genetic makeup holds components characteristic of South Asians as well as Southeast Asians. The admixture time between these components has been previously estimated on the basis of archaeology, linguistics and uniparental markers. Using genome-wide genotype data of 102 Munda speakers and contextual data from South and Southeast Asia, we retrieved admixture dates between 2000 – 3800 years ago for different populations of Munda. The best modern proxies for the source populations for the admixture with proportions 0.78/0.22 are Lao people from Laos and Dravidian speakers from Kerala in India, while the South Asian population(s), with whom the incoming Southeast Asians intermixed, had a smaller proportion of West Eurasian component than contemporary proxies. Somewhat surprisingly Malaysian Peninsular tribes rather than the geographically closer Austroasiatic languages speakers like Vietnamese and Cambodians show highest sharing of IBD segments with the Munda. In addition, we affirmed that the grouping of the Munda speakers into North and South Munda based on linguistics is in concordance with genome-wide data.

scholarly journals Natural Selection Shapes the Mosaic Ancestry of the Drosophila Genetic Reference Panel and the D. melanogaster Reference Genome

2015 ◽  
Author(s):  
John E Pool
Keyword(s):  
Natural Selection ◽  
Reference Genome ◽  
African Ancestry ◽  
Genetic Research ◽  
Reference Panel ◽  
Genome Wide ◽  
A Genome ◽  
Source Populations ◽  
Genomic Regions ◽  
Drosophila Genetic Reference Panel

North American populations of Drosophila melanogaster are thought to derive from both European and African source populations, but despite their importance for genetic research, patterns of admixture along their genomes are essentially undocumented. Here, I infer geographic ancestry along genomes of the Drosophila Genetic Reference Panel (DGRP) and the D. melanogaster reference genome. Overall, the proportion of African ancestry was estimated to be 20% for the DGRP and 9% for the reference genome. Based on the size of admixture tracts and the approximate timing of admixture, I estimate that the DGRP population underwent roughly 13.9 generations per year. Notably, ancestry levels varied strikingly among genomic regions, with significantly less African introgression on the X chromosome, in regions of high recombination, and at genes involved in specific processes such as circadian rhythm. An important role for natural selection during the admixture process was further supported by a genome-wide signal of ancestry disequilibrium, in that many between-chromosome pairs of loci showed a deficiency of Africa-Europe allele combinations. These results support the hypothesis that admixture between partially genetically isolated Drosophila populations led to natural selection against incompatible genetic variants, and that this process is ongoing. The ancestry blocks inferred here may be relevant for the performance of reference alignment in this species, and may bolster the design and interpretation of many population genetic and association mapping studies.

scholarly journals Conservation genomic analysis reveals ancient introgression and declining levels of genetic diversity in Madagascar’s hibernating dwarf lemurs

2019 ◽  
Author(s):  
Rachel C. Williams ◽  
Marina B. Blanco ◽  
Jelmer W. Poelstra ◽  
Kelsie E. Hunnicutt ◽  
Aaron A. Comeault ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Genomic Analysis ◽  
Population Level ◽  
Comparative Genomic ◽  
Effective Population ◽  
High Coverage ◽  
Genome Wide ◽  
Conservation Concern ◽  
Genomic Regions ◽  
Dwarf Lemur

AbstractMadagascar’s biodiversity is notoriously threatened by deforestation and climate change. Many of these organisms are rare, cryptic, and severely threatened, making population-level sampling unrealistic. Such is the case with Madagascar’s dwarf lemurs (genus Cheirogaleus), the only obligate hibernating primate. We here apply comparative genomic approaches to generate the first genome-wide estimates of genetic diversity within dwarf lemurs. We generate a reference genome for the fat-tailed dwarf lemur, Cheirogaleus medius, and use this resource to facilitate analyses of high-coverage (~30x) genome sequences for wild-caught individuals representing species: C. sp. cf. medius, C. major, C. crossleyi and C. sibreei. This study represents the largest contribution to date of novel genomic resources for Madagascar’s lemurs. We find concordant phylogenetic relationships among the four lineages of Cheirogaleus across most of the genome, and yet detect a number of discordant genomic regions consistent with ancient admixture. We hypothesized that these regions could have resulted from adaptive introgression related to hibernation, indeed finding that genes associated with hibernation are present, though most significantly, that gene ontology categories relating to transcription are over-represented. We estimate levels of heterozygosity and find particularly low levels in an individual sampled from an isolated population of C. medius that we refer to as C. sp. cf. medius. Results are consistent with a recent decline in effective population size, which is evident across species. Our study highlights the power of comparative genomic analysis for identifying species and populations of conservation concern, as well as for illuminating possible mechanisms of adaptive phenotypic evolution.

scholarly journals Connecting myelin-related and synaptic dysfunction in schizophrenia with SNP-rich gene expression hubs

2016 ◽  
Author(s):  
Hedi Hegyi
Keyword(s):  
Gene Expression ◽  
Gene Networks ◽  
Human Life ◽  
Pearson Correlation ◽  
Data Sets ◽  
Genome Wide ◽  
Differentially Methylated Genes ◽  
Genome Wide Data ◽  
Schizophrenic Patients ◽  
Genomic Regions

AbstractThe recent availability of several genome-wide data sets such as genome-wide mapping of SNP-rich regions and differentially methylated genes in schizophrenic individuals and gene expression data in all brain compartments across the span of human life prompted us to integrate these datasets to gain a better insight into the underlying gene networks driving this enigmatic disease.We summed up the differentially methylated “expression neighbors” (i.e. genes with positively or negatively correlating expression values) of genes that fall into one of 108 distinct schizophrenia-associated genetic loci with high number of SNPs in schizophrenic patients derived from a large cohort of pooled sequencing experiments. Surprisingly, the number of expression neighbors (with a Pearson correlation of R>=0.8 or R<=−0.7) of the genes falling into the 108 genomic regions were about 35 times higher for the positively correlating genes and 32 times higher for the negatively correlating ones than for the rest of the ~16000 genes outside these loci. While the genes in the 108 loci have relatively little known impact in schizophrenia, using this approach we identified many more known schizophrenia-related important genes with a high degree of connectedness to other genes and high scores of differentially methylated probes for their expression neighbors (such as MBP, MOBP, GRIA1, COMT, SYNGR1, MAP2 and DGCR6), validating our approach.The analysis revealed that the most positively correlating as well as the most negatively correlating genes affect synapse-related genes the most, offering an explanation and a unified view into the root cause of schizophrenia.

scholarly journals Genomic analysis of ionome-related QTLs in Arabidopsis thaliana

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Nikwan Shariatipour ◽  
Bahram Heidari ◽  
Samathmika Ravi ◽  
Piergiorgio Stevanato
Keyword(s):  
Arabidopsis Thaliana ◽  
Genome Wide Association Study ◽  
Genomic Analysis ◽  
Cell Integrity ◽  
Genomic Context ◽  
Regulatory Pathways ◽  
Physical Maps ◽  
Genome Wide ◽  
Average Confidence ◽  
Genomic Regions

AbstractIonome contributes to maintain cell integrity and acts as cofactors for catalyzing regulatory pathways. Identifying ionome contributing genomic regions provides a practical framework to dissect the genetic architecture of ionomic traits for use in biofortification. Meta-QTL (MQTL) analysis is a robust method to discover stable genomic regions for traits regardless of the genetic background. This study used information of 483 QTLs for ionomic traits identified from 12 populations for MQTL analysis in Arabidopsis thaliana. The selected QTLs were projected onto the newly constructed genetic consensus map and 33 MQTLs distributed on A. thaliana chromosomes were identified. The average confidence interval (CI) of the drafted MQTLs was 1.30 cM, reduced eight folds from a mean CI of 10.88 cM for the original QTLs. Four MQTLs were considered as stable MQTLs over different genetic backgrounds and environments. In parallel to the gene density over the A. thaliana genome, the genomic distribution of MQTLs over the genetic and physical maps indicated the highest density at non- and sub-telomeric chromosomal regions, respectively. Several candidate genes identified in the MQTLs intervals were associated with ion transportation, tolerance, and homeostasis. The genomic context of the identified MQTLs suggested nine chromosomal regions for Zn, Mn, and Fe control. The QTLs for potassium (K) and phosphorus (P) were the most frequently co-located with Zn (78.3%), Mn (76.2%), and Fe (88.2% and 70.6%) QTLs. The current MQTL analysis demonstrates that meta-QTL analysis is cheaper than, and as informative as genome-wide association study (GWAS) in refining the known QTLs.

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