scholarly journals Detecting past and ongoing natural selection among ethnically Tibetan women at high altitude in Nepal

2017 ◽  
Author(s):  
Choongwon Jeong ◽  
David B. Witonsky ◽  
Buddha Basnyat ◽  
Maniraj Neupane ◽  
Cynthia M. Beall ◽  
...  
Keyword(s):  
High Altitude ◽  
Negative Selection ◽  
Selective Sweep ◽  
Selective Pressure ◽  
Strong Association ◽  
Selective Sweeps ◽  
Genome Wide ◽  
Polygenic Adaptation ◽  
Selection For ◽  
Offspring Mortality

AbstractAdaptive evolution in humans has rarely been characterized for its whole set of components, i.e. selective pressure, adaptive phenotype, beneficial alleles and realized fitness differential. We combined approaches for detecting selective sweeps and polygenic adaptations and for mapping the genetic bases of physiological and fertility phenotypes in approximately 1000 indigenous ethnically Tibetan women from Nepal, adapted to high altitude. We performed genome-wide association analysis and tests for polygenic adaptations which showed evidence of positive selection for alleles associated with more pregnancies and live births and evidence of negative selection for those associated with higher offspring mortality. Lower hemoglobin level did not show clear evidence for polygenic adaptation, despite its strong association with an EPAS1 haplotype carrying selective sweep signals.

scholarly journals Mutations of SARS-CoV-2 nsp14 exhibit strong association with increased genome-wide mutation load

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e10181 ◽  
Author(s):  
Doğa Eskier ◽  
Aslı Suner ◽  
Yavuz Oktay ◽  
Gökhan Karakülah
Keyword(s):  
Rna Synthesis ◽  
Selective Pressure ◽  
Strong Association ◽  
Disease Spread ◽  
Replication Proteins ◽  
Mutation Load ◽  
Global Impact ◽  
Genome Wide ◽  
Genomic Variance ◽  
Viral Isolates

SARS-CoV-2 is a betacoronavirus responsible for COVID-19, a pandemic with global impact that first emerged in late 2019. Since then, the viral genome has shown considerable variance as the disease spread across the world, in part due to the zoonotic origins of the virus and the human host adaptation process. As a virus with an RNA genome that codes for its own genomic replication proteins, mutations in these proteins can significantly impact the variance rate of the genome, affecting both the survival and infection rate of the virus, and attempts at combating the disease. In this study, we analyzed the mutation densities of viral isolates carrying frequently observed mutations for four proteins in the RNA synthesis complex over time in comparison to wildtype isolates. Our observations suggest mutations in nsp14, an error-correcting exonuclease protein, have the strongest association with increased mutation load without selective pressure and across the genome, compared to nsp7, nsp8 and nsp12, which form the core polymerase complex. We propose nsp14 as a priority research target for understanding genomic variance rate in SARS-CoV-2 isolates and nsp14 mutations as potential predictors for high mutability strains.

scholarly journals A Genome-Wide Genetic Diversity Scan Reveals Multiple Signatures of Selection in a European Soybean Collection Compared to Chinese Collections of Wild and Cultivated Soybean Accessions

2021 ◽  
Vol 12 ◽  
Author(s):  
Aamir Saleem ◽  
Hilde Muylle ◽  
Jonas Aper ◽  
Tom Ruttink ◽  
Jiao Wang ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Oil Content ◽  
Selective Sweep ◽  
Germplasm Collection ◽  
Snp Markers ◽  
Selective Sweeps ◽  
Genome Wide ◽  
Population Structure Analysis ◽  
A Genome ◽  
Signatures Of Selection

Targeted and untargeted selections including domestication and breeding efforts can reduce genetic diversity in breeding germplasm and create selective sweeps in crop genomes. The genomic regions at which selective sweeps are detected can reveal important information about signatures of selection. We have analyzed the genetic diversity within a soybean germplasm collection relevant for breeding in Europe (the EUCLEG collection), and have identified selective sweeps through a genome-wide scan comparing that collection to Chinese soybean collections. This work involved genotyping of 480 EUCLEG soybean accessions, including 210 improved varieties, 216 breeding lines and 54 landraces using the 355K SoySNP microarray. SNP calling of 477 EUCLEG accessions together with 328 Chinese soybean accessions identified 224,993 high-quality SNP markers. Population structure analysis revealed a clear differentiation between the EUCLEG collection and the Chinese materials. Further, the EUCLEG collection was sub-structured into five subgroups that were differentiated by geographical origin. No clear association between subgroups and maturity group was detected. The genetic diversity was lower in the EUCLEG collection compared to the Chinese collections. Selective sweep analysis revealed 23 selective sweep regions distributed over 12 chromosomes. Co-localization of these selective sweep regions with previously reported QTLs and genes revealed that various signatures of selection in the EUCLEG collection may be related to domestication and improvement traits including seed protein and oil content, phenology, nitrogen fixation, yield components, diseases resistance and quality. No signatures of selection related to stem determinacy were detected. In addition, absence of signatures of selection for a substantial number of QTLs related to yield, protein content, oil content and phenological traits suggests the presence of substantial genetic diversity in the EUCLEG collection. Taken together, the results obtained demonstrate that the available genetic diversity in the EUCLEG collection can be further exploited for research and breeding purposes. However, incorporation of exotic material can be considered to broaden its genetic base.

scholarly journals Distinct patterns of selective sweep and polygenic adaptation

2019 ◽  
Author(s):  
Neda Barghi ◽  
Christian Schlötterer
Keyword(s):  
Allele Frequency ◽  
Computer Simulations ◽  
Selective Sweep ◽  
Empirical Work ◽  
Selective Sweeps ◽  
Adaptive Architectures ◽  
Polygenic Adaptation ◽  
Frequency Changes ◽  
Independent Effects ◽  
Distinct Features

AbstractThe central paradigm of molecular population genetics is selective sweeps, where targets of selection have independent effects on the phenotype and quickly rise to fixation. In quantitative genetics, many loci contribute epistatically to adaptation and subtle frequency changes occur at many loci. Since both paradigms could result in a sweep-like genomic signature, additional criteria are needed to distinguish them. Using the framework of experimental evolution, we performed computer simulations to study the pattern of selected alleles under both paradigms. We identify several distinct patterns of selective sweeps and polygenic adaptation in populations of different sizes. These features could provide the foundation for development of quantitative approaches to differentiate the two paradigms.Author’s summaryThe selective sweep model assumes an independent frequency increase of favorable alleles and has been the basis of many tests for selection. While, polygenic adaptation is typically modelled by small frequency shifts in many loci. Recently, some theoretical and empirical work demonstrated that polygenic adaptation, similar to sweep, could also results in pronounced allele frequency changes. These results suggest that other distinct features need to be identified. Using computer simulations, we identified distinctive features for each paradigm that can be used to differentiate the sweep model from polygenic adaptation. Features such as allele frequency trajectories, time-series fitness, distribution of selected alleles on haplotypes, and parallelism among replicates can be used for development of suitable tests to distinguish between different adaptive architectures. These features provide the basis for theoretical modeling, design of selection experiments and data analysis.

scholarly journals Genome-wide selective sweep analysis of the high-altitude adaptability of yaks by using the copy number variant

3 Biotech ◽  
2020 ◽  
Vol 10 (6) ◽  
Author(s):  
E. Guang-Xin ◽  
Bai-Gao Yang ◽  
Yan-Bin Zhu ◽  
Xing-Hai Duang ◽  
Wang-Dui Basang ◽  
...  
Keyword(s):  
High Altitude ◽  
Copy Number ◽  
Selective Sweep ◽  
Copy Number Variant ◽  
Genome Wide

scholarly journals Mutations of SARS-CoV-2 nsp14 exhibit strong association with increased genome-wide mutation load

2020 ◽  
Author(s):  
Doğa Eskier ◽  
Aslı Suner ◽  
Yavuz Oktay ◽  
Gökhan Karakülah
Keyword(s):  
Rna Synthesis ◽  
Selective Pressure ◽  
Strong Association ◽  
Disease Spread ◽  
Replication Proteins ◽  
Mutation Load ◽  
Global Impact ◽  
Genome Wide ◽  
Genomic Variance ◽  
Viral Isolates

AbstractSARS-CoV-2 is a betacoronavirus responsible for human cases of COVID-19, a pandemic with global impact that first emerged in late 2019. Since then, the viral genome has shown considerable variance as the disease spread across the world, in part due to the zoonotic origins of the virus and the human host adaptation process. As a virus with an RNA genome that codes for its own genomic replication proteins, mutations in these proteins can significantly impact the variance rate of the genome, affecting both the survival and infection rate of the virus, and attempts at combating the disease. In this study, we analyzed the mutation densities of viral isolates carrying frequently observed mutations for four proteins in the RNA synthesis complex over time in comparison to wildtype isolates. Our observations suggest mutations in nsp14, an error-correcting exonuclease protein, have the strongest association with increased mutation load in both regions without selective pressure and across the genome, compared to nsp7, 8, and 12, which form the core polymerase complex. We propose nsp14 as a priority research target for understanding genomic variance rate in SARS-CoV-2 isolates, and nsp14 mutations as potential predictors for high mutability strains.

High Altitude hypoxia

2020 ◽  
Vol 17 ◽  
Author(s):  
Asma Babar ◽  
Kifayatullah Mengal ◽  
Abdul Hanan Babar ◽  
Shixin Wu ◽  
Mujahid Ali Shah ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
High Altitude ◽  
Molecular Mechanisms ◽  
Strong Association ◽  
Haemoglobin Concentration ◽  
Metabolic Reprogramming ◽  
Molecular Networks ◽  
Whole Genome ◽  
Gene Expressions ◽  
Transcriptional Responses

: The world highest and largest altitude area is called the Qinghai-Tibetan plateau (QTB), which harbors unique animal and plant species. Mammals that inhabit the higher altitude regions have adapted well to the hypoxic conditions. One of the main stressors at high altitude is hypoxia. Metabolic responses to hypoxia play important roles in cell survival strategies and some diseases. However, the homeostatic alterations that equilibrate variations in the demand and supply of energy to maintain organismal function in a prolonged low O2 environment persist partly understood, making it problematic to differentiate adaptive from maladaptive responses in hypoxia. Tibetans and yaks are two perfect examples innate to the plateau for high altitude adaptation. By the scan of the whole-genome, EPAS1 and EGLN1 were identified as key genes associated with sustained haemoglobin concentration in high altitude mammals for adaptation. The yak is a much more ancient mammal which has existed on QTB longer than humans, it is, therefore, possible that natural selection represented a diverse group of genes/pathways in yaks. Physiological characteristics are extremely informative in revealing molecular networks associated with inherited adaptation, in addition to the whole-genome adaptive changes at the DNA sequence level. Gene-expression can be changed by a variety of signals originating from the environment, and hypoxia is the main factor amongst them. The hypoxia-inducible factors (HIF-1α and EPAS1/HIF-2α) are the main regulators of oxygen in homeostasis which play a role as maestro regulators of adaptation in hypoxic reaction of molecular mechanisms. (Vague) The basis of this review is to present recent information regarding the molecular mechanism involved in hypoxia that regulates candidate genes and proteins. Many transcriptional responses toward hypoxia are facilitated by HIFs that change the number of gene expressions and help in angiogenesis, erythropoiesis, metabolic reprogramming and metastasis. HIFs also activate several signals highlighting a strong association between hypoxia, the misfolded proteins’ accumulation in the endoplasmic reticulum in stress and activation of unfolded protein response (UPR). It was observed that at high-altitude, pregnancies yield a low birth weight ∼100 g per1000 m of the climb. (Vague) It may involve variation in the events of energy-demanding, like protein synthesis. Prolonged hypobaric hypoxia causes placental ER stress, which in turn, moderates protein synthesis and reduces proliferation. Further, Cardiac hypertrophy by cytosolic Ca2+ raises and Ca2+/calmodulin, calcineurin stimulation, NF-AT3 pathway might be caused by an imbalance in Sarcoplasmic reticulum ER Ca2, might be adaptive in beginning but severe later.

scholarly journals Natural variation in fecundity is correlated with species-wide levels of divergence in Caenorhabditis elegans

2021 ◽  
Author(s):  
Gaotian Zhang ◽  
Jake D Mostad ◽  
Erik C Andersen
Keyword(s):  
Life History ◽  
Caenorhabditis Elegans ◽  
Life History Traits ◽  
Life History Trait ◽  
Selective Sweeps ◽  
C Elegans ◽  
Genome Wide ◽  
Genetic Complexity ◽  
Genomic Regions ◽  
Global Population

Abstract Life history traits underlie the fitness of organisms and are under strong natural selection. A new mutation that positively impacts a life history trait will likely increase in frequency and become fixed in a population (e.g. a selective sweep). The identification of the beneficial alleles that underlie selective sweeps provides insights into the mechanisms that occurred during the evolution of a species. In the global population of Caenorhabditis elegans, we previously identified selective sweeps that have drastically reduced chromosomal-scale genetic diversity in the species. Here, we measured the fecundity of 121 wild C. elegans strains, including many recently isolated divergent strains from the Hawaiian islands and found that strains with larger swept genomic regions have significantly higher fecundity than strains without evidence of the recent selective sweeps. We used genome-wide association (GWA) mapping to identify three quantitative trait loci (QTL) underlying the fecundity variation. Additionally, we mapped previous fecundity data from wild C. elegans strains and C. elegans recombinant inbred advanced intercross lines that were grown in various conditions and detected eight QTL using GWA and linkage mappings. These QTL show the genetic complexity of fecundity across this species. Moreover, the haplotype structure in each GWA QTL region revealed correlations with recent selective sweeps in the C. elegans population. North American and European strains had significantly higher fecundity than most strains from Hawaii, a hypothesized origin of the C. elegans species, suggesting that beneficial alleles that caused increased fecundity could underlie the selective sweeps during the worldwide expansion of C. elegans.

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