Difference in the Proportions of Deleterious Variations Within and Between Populations Influences the Estimation of FST

2021 ◽  
Author(s):  
Sankar Subramanian
Keyword(s):  
Evolutionary Biology ◽  
Purifying Selection ◽  
Population Diversity ◽  
Fixation Index ◽  
Population Divergence ◽  
Whole Genome ◽  
Genome Data ◽  
Important Measure ◽  
Spanish Populations ◽  
Over Time

Abstract Estimating the extent of genetic differentiation between populations is an important measure in population genetics, ecology and evolutionary biology. Fixation index or FST is an important measure, which is routinely used to quantify this. Previous studies have shown that FST estimated for selectively constrained regions was significantly lower than that estimated for neutral regions. By deriving the theoretical relationship between FST at neutral and constrained sites we show that an excess in the fraction of deleterious variations segregating within populations compared to that segregates between populations is the cause for the reduction in FST estimated at constrained sites. Using whole genome data, our results revealed that the magnitude of reduction in FST estimates obtained for selectively constrained regions was much higher for distantly related populations compared to those estimated for closely related pairs. For example, the reduction was 47% for comparison between Europeans-Africans, 30% for European-Asian comparison, 16% for the Northern-Southern European pair and only 4% for the comparison involving two Southern European (Italian and Spanish) populations. Since deleterious variants are purged over time due to purifying selection, their contribution to the among-population diversity at constrained sites decreases with the increase in the divergence between populations. However, within-population diversity remains the same for all pairs compared and therefore FST estimated at constrained sites for distantly related populations are much smaller than those estimated for closely related populations. Our results suggest that the level of population divergence should be considered when comparing constrained site FST estimates from different pairs of populations.

scholarly journals Temporal distribution of deleterious variations influences the estimation of FST

2019 ◽  
Author(s):  
Sankar Subramanian
Keyword(s):  
Evolutionary Biology ◽  
Temporal Distribution ◽  
Purifying Selection ◽  
Population Diversity ◽  
Fixation Index ◽  
Population Divergence ◽  
Genome Data ◽  
Important Measure ◽  
African Populations ◽  
Spanish Populations

AbstractEstimating the extent of genetic differentiation between populations is an important measure in population genetics, ecology and evolutionary biology. Fixation index or FST is an important measure, which is routinely used to quantify this. Previous studies have shown that FST estimated for selectively constrained regions was significantly lower than that estimated for neutral regions. By deriving the theoretical relationship between FST at neutral and constrained sites we show that an excess in the fraction of deleterious variations segregating within populations compared to that segregates between populations is the cause for the reduction in FST estimated at constrained sites. Using whole genome data, our results revealed that the magnitude of reduction in FST estimates obtained for selectively constrained regions was much higher for distantly related populations compared to those estimated for closely related pairs. For example, the reduction was 49% for comparison between European-African populations, 31% for European-Asian comparison, 16% for the Northern-Southern European pair and only 4% for the comparison involving two Southern European (Italian and Spanish) populations. Since deleterious variants are purged over time due to purifying selection, their contribution to the among population diversity at constrained sites decreases with the increase in the divergence between populations. However, within population diversity remain the same for all pairs compared above and therefore FST estimated at constrained sites for distantly related populations are much smaller than those estimated for closely related populations. Our results suggest that the level of population divergence should be considered when comparing constrained site FST estimates obtained for different pairs of populations.

scholarly journals Vulnerability to Fishing and Life History Traits Correlate with the Load of Deleterious Mutations in Teleosts

2020 ◽  
Vol 37 (8) ◽  
pp. 2192-2196 ◽  
Author(s):  
Jonathan Rolland ◽  
Dolph Schluter ◽  
Jonathan Romiguier
Keyword(s):  
Life History ◽  
Evolutionary Biology ◽  
Life History Traits ◽  
Deleterious Mutation ◽  
Purifying Selection ◽  
Synonymous Substitution ◽  
Deleterious Mutations ◽  
Data Set ◽  
Terrestrial Vertebrates ◽  
Genome Data

Abstract Understanding why some species accumulate more deleterious substitutions than others is an important question relevant in evolutionary biology and conservation sciences. Previous studies conducted in terrestrial taxa suggest that life history traits correlate with the efficiency of purifying selection and accumulation of deleterious mutations. Using a large genome data set of 76 species of teleostean fishes, we show that species with life history traits associated with vulnerability to fishing have an increased rate of deleterious mutation accumulation (measured via dN/dS, i.e., nonsynonymous over synonymous substitution rate). Our results, focusing on a large clade of aquatic species, generalize previous patterns found so far in few clades of terrestrial vertebrates. These results also show that vulnerable species to fishing inherently accumulate more deleterious substitutions than nonthreatened ones, which illustrates the potential links among population genetics, ecology, and fishing policies to prevent species extinction.

The Evolutionary Biology of Species

2019 ◽  
Author(s):  
Timothy G. Barraclough
Keyword(s):  
Evolutionary Biology ◽  
Biological Diversity ◽  
Distinct Species ◽  
Species Boundaries ◽  
Central Thesis ◽  
Species Accumulation ◽  
Multicellular Organisms ◽  
Broad Approach ◽  
Over Time

‘Species’ are central to understanding the origin and dynamics of biological diversity; explaining why lineages split into multiple distinct species is one of the main goals of evolutionary biology. However, the existence of species is often taken for granted, and precisely what is meant by species and whether they really exist as a pattern of nature has rarely been modelled or critically tested. This novel book presents a synthetic overview of the evolutionary biology of species, describing what species are, how they form, the consequences of species boundaries and diversity for evolution, and patterns of species accumulation over time. The central thesis is that species represent more than just a unit of taxonomy; they are a model of how diversity is structured as well as how groups of related organisms evolve. The author adopts an intentionally broad approach to consider what species constitute, both theoretically and empirically, and how we detect them, drawing on a wealth of examples from microbes to multicellular organisms.

scholarly journals Transcriptome Expression of Biomineralization Genes in Littoraria flava Gastropod in Brazilian Rocky Shore Reveals Evidence of Local Adaptation

2021 ◽  
Vol 13 (4) ◽  
Author(s):  
Camilla A Santos ◽  
Gabriel G Sonoda ◽  
Thainá Cortez ◽  
Luiz L Coutinho ◽  
Sónia C S Andrade
Keyword(s):  
Local Adaptation ◽  
Differentially Expressed Genes ◽  
Evolutionary Biology ◽  
Rocky Shore ◽  
Expression Patterns ◽  
Purifying Selection ◽  
Marine Species ◽  
Differentially Expressed ◽  
Planktonic Larva ◽  
Structure Changes

Abstract Understanding how selection shapes population differentiation and local adaptation in marine species remains one of the greatest challenges in the field of evolutionary biology. The selection of genes in response to environment-specific factors and microenvironmental variation often results in chaotic genetic patchiness, which is commonly observed in rocky shore organisms. To identify these genes, the expression profile of the marine gastropod Littoraria flava collected from four Southeast Brazilian locations in ten rocky shore sites was analyzed. In this first L. flava transcriptome, 250,641 unigenes were generated, and 24% returned hits after functional annotation. Independent paired comparisons between 1) transects, 2) sites within transects, and 3) sites from different transects were performed for differential expression, detecting 8,622 unique differentially expressed genes. Araçá (AR) and São João (SJ) transect comparisons showed the most divergent gene products. For local adaptation, fitness-related differentially expressed genes were chosen for selection tests. Nine and 24 genes under adaptative and purifying selection, respectively, were most related to biomineralization in AR and chaperones in SJ. The biomineralization-genes perlucin and gigasin-6 were positively selected exclusively in the site toward the open ocean in AR, with sequence variants leading to pronounced protein structure changes. Despite an intense gene flow among L. flava populations due to its planktonic larva, gene expression patterns within transects may be the result of selective pressures. Our findings represent the first step in understanding how microenvironmental genetic variation is maintained in rocky shore populations and the mechanisms underlying local adaptation in marine species.

scholarly journals Rapid Spread of the SARS-CoV-2 Variant of Concern 202012/01 in Southern Italy (December 2020–March 2021)

2021 ◽  
Vol 18 (9) ◽  
pp. 4766
Author(s):  
Daniela Loconsole ◽  
Francesca Centrone ◽  
Caterina Morcavallo ◽  
Silvia Campanella ◽  
Anna Sallustio ◽  
...  
Keyword(s):  
Clinical Characteristics ◽  
Large Scale ◽  
Southern Italy ◽  
Whole Genome ◽  
Third Wave ◽  
Gene Target ◽  
The Third ◽  
Rapid Spread ◽  
Pharmaceutical Interventions ◽  
Over Time

Epidemiological and virological studies have revealed that SARS-CoV-2 variants of concern (VOCs) are emerging globally, including in Europe. The aim of this study was to evaluate the spread of B.1.1.7-lineage SARS-CoV-2 in southern Italy from December 2020–March 2021 through the detection of the S gene target failure (SGTF), which could be considered a robust proxy of VOC B.1.1.7. SGTF was assessed on 3075 samples from week 52/2020 to week 10/2021. A subset of positive samples identified in the Apulia region during the study period was subjected to whole-genome sequencing (WGS). A descriptive and statistical analysis of the demographic and clinical characteristics of cases according to SGTF status was performed. Overall, 20.2% of samples showed SGTF; 155 strains were confirmed as VOC 202012/01 by WGS. The proportion of SGTF-positive samples rapidly increased over time, reaching 69.2% in week 10/2021. SGTF-positive cases were more likely to be symptomatic and to result in hospitalization (p < 0.0001). Despite the implementation of large-scale non-pharmaceutical interventions (NPIs), such as the closure of schools and local lockdowns, a rapid spread of VOC 202012/01 was observed in southern Italy. Strengthened NPIs and rapid vaccine deployment, first among priority groups and then among the general population, are crucial both to contain the spread of VOC 202012/01 and to flatten the curve of the third wave.

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.

46 Footprints of Selection in Angus and Hanwoo Beef Cattle Using Imputed Whole Genome Sequence Data

2021 ◽  
Vol 99 (Supplement_3) ◽  
pp. 25-25
Author(s):  
Muhammad Yasir Nawaz ◽  
Rodrigo Pelicioni Savegnago ◽  
Cedric Gondro
Keyword(s):  
Beef Cattle ◽  
Genome Sequence ◽  
Sequence Data ◽  
Whole Genome Sequence ◽  
Fixation Index ◽  
Whole Genome ◽  
Extended Haplotype Homozygosity ◽  
Extended Haplotype ◽  
Genome Sequence Data ◽  
Genomic Regions

Abstract In this study, we detected genome wide footprints of selection in Hanwoo and Angus beef cattle using different allele frequency and haplotype-based methods based on imputed whole genome sequence data. Our dataset included 13,202 Angus and 10,437 Hanwoo animals with 10,057,633 and 13,241,550 imputed SNPs, respectively. A subset of data with 6,873,624 common SNPs between the two populations was used to estimate signatures of selection parameters, both within (runs of homozygosity and extended haplotype homozygosity) and between (allele fixation index, extended haplotype homozygosity) the breeds in order to infer evidence of selection. We observed that correlations between various measures of selection ranged between 0.01 to 0.42. Assuming these parameters were complementary to each other, we combined them into a composite selection signal to identify regions under selection in both beef breeds. The composite signal was based on the average of fractional ranks of individual selection measures for every SNP. We identified some selection signatures that were common between the breeds while others were independent. We also observed that more genomic regions were selected in Angus as compared to Hanwoo. Candidate genes within significant genomic regions may help explain mechanisms of adaptation, domestication history and loci for important traits in Angus and Hanwoo cattle. In the future, we will use the top SNPs under selection for genomic prediction of carcass traits in both breeds.

148 Multiple Dysregulated Novel Pathways and Genes in Aleutian Mink Disease Revealed by Selection Signatures and Gene Network Analyses Using Whole-genome Sequence Data

2021 ◽  
Vol 99 (Supplement_3) ◽  
pp. 76-76
Author(s):  
Seyed Milad Vahedi ◽  
Karim Karimi ◽  
Siavash Salek Ardestani ◽  
Younes Miar
Keyword(s):  
Sequence Data ◽  
American Mink ◽  
Enrichment Analysis ◽  
Whole Genome Sequence ◽  
Fixation Index ◽  
Pathway Enrichment Analysis ◽  
Whole Genome ◽  
Nucleotide Polymorphisms ◽  
Network Analyses ◽  
Genome Level

Abstract Aleutian disease (AD) is a chronic persistent infection in domestic mink caused by Aleutian mink disease virus (AMDV). Female mink’s fertility and pelt quality depression are the main reasons for the AD’s negative economic impacts on the mink industry. A total number of 79 American mink from the Canadian Center for Fur Animal Research at Dalhousie University (Truro, NS, Canada) were classified based on the results of counter immunoelectrophoresis (CIEP) tests into two groups of positive (n = 48) and negative (n = 31). Whole-genome sequences comprising 4,176 scaffolds and 8,039,737 single nucleotide polymorphisms (SNPs) were used to trace the selection footprints for response to AMDV infection at the genome level. Window-based fixation index (Fst) and nucleotide diversity (θπ) statistics were estimated to compare positive and negative animals’ genomes. The overlapped top 1% genomic windows between two statistics were considered as potential regions underlying selection pressures. A total of 98 genomic regions harboring 33 candidate genes were detected as selective signals. Most of the identified genes were involved in the development and functions of immune system (PPP3CA, SMAP2, TNFRSF21, SKIL, and AKIRIN2), musculoskeletal system (COL9A2, PPP1R9A, ANK2, AKAP9, and STRIT1), nervous system (ASCL1, ZFP69B, SLC25A27, MCF2, and SLC7A14), reproductive system (CAMK2D, GJB7, SSMEM1, C6orf163), liver (PAH and DPYD), and lung (SLC35A1). Gene-expression network analysis showed the interactions among 27 identified genes. Moreover, pathway enrichment analysis of the constructed genes network revealed significant oxytocin (KEGG: hsa04921) and GnRH signaling (KEGG: hsa04912) pathways, which are likely to be impaired by AMDV leading to dams’ fecundity reduction. These results provided a perspective to the genetic architecture of response to AD in American mink and novel insight into the pathogenesis of AMDV.

scholarly journals Matching loci surveyed to questions asked in phylogeography

2016 ◽  
Vol 283 (1826) ◽  
pp. 20152340 ◽  
Author(s):  
Chih-Ming Hung ◽  
Sergei V. Drovetski ◽  
Robert M. Zink
Keyword(s):  
Population Diversity ◽  
Single Locus ◽  
Population Divergence ◽  
Summary Statistics ◽  
Recent Past ◽  
Size Change ◽  
The Caucasus ◽  
Nuclear Loci ◽  
The Difference ◽  
Coalescent Time

Although mitochondrial DNA (mtDNA) has long been used for assessing genetic variation within and between populations, its workhorse role in phylogeography has been criticized owing to its single-locus nature. The only choice for testing mtDNA results is to survey nuclear loci, which brings into contrast the difference in locus effective size and coalescence times. Thus, it remains unclear how erroneous mtDNA-based estimates of species history might be, especially for evolutionary events in the recent past. To test the robustness of mtDNA and nuclear sequences in phylogeography, we provide one of the largest paired comparisons of summary statistics and demographic parameters estimated from mitochondrial, five Z-linked and 10 autosomal genes of 30 avian species co-distributed in the Caucasus and Europe. The results suggest that mtDNA is robust in estimating inter-population divergence but not in intra-population diversity, which is sensitive to population size change. Here, we provide empirical evidence showing that mtDNA was more likely to detect population divergence than any other single locus owing to its smaller N e and thus faster coalescent time. Therefore, at least in birds, numerous studies that have based their inferences of phylogeographic patterns solely on mtDNA should not be readily dismissed.

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