scholarly journals Evolutionary analysis of vision genes identifies potential drivers of visual differences between giraffe and okapi

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e3145 ◽  
Author(s):  
Edson Ishengoma ◽  
Morris Agaba ◽  
Douglas R. Cavener
Keyword(s):  
Positive Selection ◽  
Visual Signal ◽  
Evolutionary Analysis ◽  
Long Distance ◽  
Phenotypic Differences ◽  
Multiple Strategies ◽  
Branch Site ◽  
Signature Of Selection ◽  
Evolutionary Success ◽  
Signatures Of Selection

BackgroundThe capacity of visually oriented species to perceive and respond to visual signal is integral to their evolutionary success. Giraffes are closely related to okapi, but the two species have broad range of phenotypic differences including their visual capacities. Vision studies rank giraffe’s visual acuity higher than all other artiodactyls despite sharing similar vision ecological determinants with many of them. The extent to which the giraffe’s unique visual capacity and its difference with okapi is reflected by changes in their vision genes is not understood.MethodsThe recent availability of giraffe and okapi genomes provided opportunity to identify giraffe and okapi vision genes. Multiple strategies were employed to identify thirty-six candidate mammalian vision genes in giraffe and okapi genomes. Quantification of selection pressure was performed by a combination of branch-site tests of positive selection and clade models of selection divergence through comparing giraffe and okapi vision genes and orthologous sequences from other mammals.ResultsSignatures of selection were identified in key genes that could potentially underlie giraffe and okapi visual adaptations. Importantly, some genes that contribute to optical transparency of the eye and those that are critical in light signaling pathway were found to show signatures of adaptive evolution or selection divergence. Comparison between giraffe and other ruminants identifies significant selection divergence inCRYAAandOPN1LW. Significant selection divergence was identified inSAGwhile positive selection was detected inLUMwhen okapi is compared with ruminants and other mammals. Sequence analysis ofOPN1LWshowed that at least one of the sites known to affect spectral sensitivity of the red pigment is uniquely divergent between giraffe and other ruminants.DiscussionBy taking a systemic approach to gene function in vision, the results provide the first molecular clues associated with giraffe and okapi vision adaptations. At least some of the genes that exhibit signature of selection may reflect adaptive response to differences in giraffe and okapi habitat. We hypothesize that requirement for long distance vision associated with predation and communication with conspecifics likely played an important role in the adaptive pressure on giraffe vision genes.

scholarly journals Evolutionary analysis of vision genes identifies potential drivers of visual differences between giraffe and okapi

2016 ◽  
Author(s):  
Edson Ishengoma ◽  
Morris Agaba ◽  
Douglas R Cavener
Keyword(s):  
Positive Selection ◽  
Visual Signal ◽  
Evolutionary Analysis ◽  
Long Distance ◽  
Phenotypic Differences ◽  
Multiple Strategies ◽  
Branch Site ◽  
Signature Of Selection ◽  
Evolutionary Success ◽  
Site Test

Background. The capacity of species to respond and perceive visual signal is integral to their evolutionary success. Giraffe is closely related to okapi, but the two species have broad range of phenotypic differences including their visual capacities. Vision studies rank giraffe’s visual acuity higher than all other artiodactyls despite sharing similar vision ecological determinants with most of them. To what extent giraffe unique visual capacity and its difference with okapi is reflected by changes in their vision genes is not understood. Methods. The recent availability of giraffe and okapi genome provided opportunity to identify giraffe and okapi vision genes. Multiple strategies were employed to identify thirty-six candidate mammalian vision genes in giraffe and okapi genomes. Quantification of selection pressure was performed by a combination of branch-site test of positive selection and clade models of selection divergence through comparing giraffe and okapi vision genes and their corresponding orthologous sequences from other mammals obtained from public gene banks. Results. Signatures of selection was identified in key genes that could potentially underlie giraffe and okapi visual adaptations. Importantly, some genes that contribute to optical transparency of the eye and those that are critical in light signaling pathway were found to show signatures of adaptive evolution or selection divergence. Comparison between giraffe and other ruminants identifies significant selection divergence in CRYAA and OPN1LW in giraffe. Significant selection divergence was identified in SAG while positive selection was detected in LUM when okapi is compared with ruminants and other mammals. Sequence analysis of OPN1LW showed that at least one of the sites known to affect spectral sensitivity of the red pigment is uniquely divergent between giraffe and other ruminants. Discussion. By taking a systemic approach to gene function in vision, the results provide the first molecular clues associated with giraffe and okapi vision adaptation. At least some of the genes that exhibit signature of selection may reflect adaptive response to differences in giraffe and okapi habitat. Moreover, requirement for long distance vision associated with predation likely played an important role in the adaptive pressure on giraffe vision genes.

scholarly journals Evolutionary analysis of vision genes identifies potential drivers of visual differences between giraffe and okapi

2016 ◽  
Author(s):  
Edson Ishengoma ◽  
Morris Agaba ◽  
Douglas R Cavener
Keyword(s):  
Positive Selection ◽  
Visual Signal ◽  
Evolutionary Analysis ◽  
Long Distance ◽  
Phenotypic Differences ◽  
Multiple Strategies ◽  
Branch Site ◽  
Signature Of Selection ◽  
Evolutionary Success ◽  
Site Test

Background. The capacity of species to respond and perceive visual signal is integral to their evolutionary success. Giraffe is closely related to okapi, but the two species have broad range of phenotypic differences including their visual capacities. Vision studies rank giraffe’s visual acuity higher than all other artiodactyls despite sharing similar vision ecological determinants with most of them. To what extent giraffe unique visual capacity and its difference with okapi is reflected by changes in their vision genes is not understood. Methods. The recent availability of giraffe and okapi genome provided opportunity to identify giraffe and okapi vision genes. Multiple strategies were employed to identify thirty-six candidate mammalian vision genes in giraffe and okapi genomes. Quantification of selection pressure was performed by a combination of branch-site test of positive selection and clade models of selection divergence through comparing giraffe and okapi vision genes and their corresponding orthologous sequences from other mammals obtained from public gene banks. Results. Signatures of selection was identified in key genes that could potentially underlie giraffe and okapi visual adaptations. Importantly, some genes that contribute to optical transparency of the eye and those that are critical in light signaling pathway were found to show signatures of adaptive evolution or selection divergence. Comparison between giraffe and other ruminants identifies significant selection divergence in CRYAA and OPN1LW in giraffe. Significant selection divergence was identified in SAG while positive selection was detected in LUM when okapi is compared with ruminants and other mammals. Sequence analysis of OPN1LW showed that at least one of the sites known to affect spectral sensitivity of the red pigment is uniquely divergent between giraffe and other ruminants. Discussion. By taking a systemic approach to gene function in vision, the results provide the first molecular clues associated with giraffe and okapi vision adaptation. At least some of the genes that exhibit signature of selection may reflect adaptive response to differences in giraffe and okapi habitat. Moreover, requirement for long distance vision associated with predation likely played an important role in the adaptive pressure on giraffe vision genes.

scholarly journals SARS-CoV-2 sequence typing, evolution and signatures of selection using CoVa, a Python-based command-line utility

2020 ◽  
Author(s):  
Farhan Ali ◽  
Mohak Sharda ◽  
Aswin Sai Narain Seshasayee
Keyword(s):  
Positive Selection ◽  
Evolutionary Analysis ◽  
Community Needs ◽  
Geographical Patterns ◽  
Global Pandemic ◽  
Signatures Of Selection ◽  
Genome Analyses ◽  
User Friendly ◽  
Near Future

AbstractThe current global pandemic COVID-19, caused by SARS-CoV-2, has resulted in millions of infections worldwide in a few months. Global efforts to tackle this situation have produced a tremendous body of genomic data, which can be used for tracing transmission routes, characterization of isolates, and monitoring variants with potential for unusual virulence. Several groups have analyzed these genomes using different approaches. However, as new data become available, the research community needs a pipeline to perform a set of routine analyses, that can quickly incorporate new genome sequences and update the analysis reports. We developed a programmatic tool, CoVa, with this objective. It is a fast, accurate and user-friendly utility to perform a variety of genome analyses on hundreds of SARS-CoV-2 sequences. Using CoVa, we define a modified sequence typing nomenclature and identify sites under positive selection. Further analysis identified some peptides and sites showing geographical patterns of selection. Specifically, we show differences in sequence type distribution between sequences from India and those from the rest of the world. We also show that several sites show signatures of positive selection uniquely in sequences from India. Preliminary evolutionary analysis, using features that will be incorporated into CoVa in the near future, show a mutation rate of 7.4 × 10−4 substitutions/site/year, confirm a temporal signal with a November 2019 origin of SARS-CoV-2, and a heterogeneity in the geographical distribution of Indian samples.

A Phenotype–Genotype Codon Model for Detecting Adaptive Evolution

2019 ◽  
Vol 69 (4) ◽  
pp. 722-738 ◽  
Author(s):  
Christopher T Jones ◽  
Noor Youssef ◽  
Edward Susko ◽  
Joseph P Bielawski
Keyword(s):  
Positive Selection ◽  
Adaptive Evolution ◽  
Evolutionary History ◽  
Life History Trait ◽  
Molecular Adaptation ◽  
Simulation Studies ◽  
Site Model ◽  
Branch Site ◽  
A Site ◽  
Post Hoc

Abstract A central objective in biology is to link adaptive evolution in a gene to structural and/or functional phenotypic novelties. Yet most analytic methods make inferences mainly from either phenotypic data or genetic data alone. A small number of models have been developed to infer correlations between the rate of molecular evolution and changes in a discrete or continuous life history trait. But such correlations are not necessarily evidence of adaptation. Here, we present a novel approach called the phenotype–genotype branch-site model (PG-BSM) designed to detect evidence of adaptive codon evolution associated with discrete-state phenotype evolution. An episode of adaptation is inferred under standard codon substitution models when there is evidence of positive selection in the form of an elevation in the nonsynonymous-to-synonymous rate ratio $\omega$ to a value $\omega > 1$. As it is becoming increasingly clear that $\omega > 1$ can occur without adaptation, the PG-BSM was formulated to infer an instance of adaptive evolution without appealing to evidence of positive selection. The null model makes use of a covarion-like component to account for general heterotachy (i.e., random changes in the evolutionary rate at a site over time). The alternative model employs samples of the phenotypic evolutionary history to test for phenomenological patterns of heterotachy consistent with specific mechanisms of molecular adaptation. These include 1) a persistent increase/decrease in $\omega$ at a site following a change in phenotype (the pattern) consistent with an increase/decrease in the functional importance of the site (the mechanism); and 2) a transient increase in $\omega$ at a site along a branch over which the phenotype changed (the pattern) consistent with a change in the site’s optimal amino acid (the mechanism). Rejection of the null is followed by post hoc analyses to identify sites with strongest evidence for adaptation in association with changes in the phenotype as well as the most likely evolutionary history of the phenotype. Simulation studies based on a novel method for generating mechanistically realistic signatures of molecular adaptation show that the PG-BSM has good statistical properties. Analyses of real alignments show that site patterns identified post hoc are consistent with the specific mechanisms of adaptation included in the alternate model. Further simulation studies show that the covarion-like component of the PG-BSM plays a crucial role in mitigating recently discovered statistical pathologies associated with confounding by accounting for heterotachy-by-any-cause. [Adaptive evolution; branch-site model; confounding; mutation-selection; phenotype–genotype.]

scholarly journals Genome-Wide Runs of Homozygosity, Effective Population Size, and Detection of Positive Selection Signatures in Six Chinese Goat Breeds

Genes ◽  
2019 ◽  
Vol 10 (11) ◽  
pp. 938 ◽  
Author(s):  
Islam ◽  
Li ◽  
Liu ◽  
Berihulay ◽  
Abied ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Genetic Differentiation ◽  
Positive Selection ◽  
Candidate Genes ◽  
Runs Of Homozygosity ◽  
Selection Signatures ◽  
Effective Population ◽  
Signature Of Selection ◽  
Genomic Regions ◽  
Insight Into

: Detection of selection footprints provides insight into the evolution process and the underlying mechanisms controlling the phenotypic diversity of traits that have been exposed to selection. Selection focused on certain characters, mapping certain genomic regions often shows a loss of genetic diversity with an increased level of homozygosity. Therefore, the runs of homozygosity (ROHs), homozygosity by descent (HBD), and effective population size (Ne) are effective tools for exploring the genetic diversity, understanding the demographic history, foretelling the signature of directional selection, and improving the breeding strategies to use and conserve genetic resources. We characterized the ROH, HBD, Ne, and signature of selection of six Chinese goat populations using single nucleotide polymorphism (SNP) 50K Illumina beadchips. Our results show an inverse relationship between the length and frequency of ROH. A long ROH length, higher level of inbreeding, long HBD segment, and smaller Ne in Guangfeng (GF) goats suggested intensive selection pressure and recent inbreeding in this breed. We identified six reproduction-related genes within the genomic regions with a high ROH frequency, of which two genes overlapped with a putative selection signature. The estimated pair-wise genetic differentiation (FST) among the populations is 9.60% and the inter- and intra-population molecular variations are 9.68% and 89.6%, respectively, indicating low to moderate genetic differentiation. Our selection signatures analysis revealed 54 loci harboring 86 putative candidate genes, with a strong signature of selection. Further analysis showed that several candidate genes, including MARF1, SYCP2, TMEM200C, SF1, ADCY1, and BMP5, are involved in goat fecundity. We identified 11 candidate genes by using cross-population extended haplotype homozygosity (XP-EHH) estimates, of which MARF1 and SF1 are under strong positive selection, as they are differentiated in high and low reproduction groups according to the three approaches used. Gene ontology enrichment analysis revealed that different biological pathways could be involved in the variation of fecundity in female goats. This study provides a new insight into the ROHs patterns for maintenance of within breed diversity and suggests a role of positive selection for genetic variation influencing fecundity in Chinese goat.

scholarly journals Integrated structural and evolutionary analysis reveals common mechanisms underlying adaptive evolution in mammals

2020 ◽  
Vol 117 (11) ◽  
pp. 5977-5986 ◽  
Author(s):  
Greg Slodkowicz ◽  
Nick Goldman
Keyword(s):  
Positive Selection ◽  
Adaptive Evolution ◽  
Evolutionary Biology ◽  
Molecular Mechanisms ◽  
Structural Information ◽  
Protein Structures ◽  
Unexpected Finding ◽  
Evolutionary Analysis ◽  
Genomic Scale ◽  
Evolution Of Mammals

Understanding the molecular basis of adaptation to the environment is a central question in evolutionary biology, yet linking detected signatures of positive selection to molecular mechanisms remains challenging. Here we demonstrate that combining sequence-based phylogenetic methods with structural information assists in making such mechanistic interpretations on a genomic scale. Our integrative analysis shows that positively selected sites tend to colocalize on protein structures and that positively selected clusters are found in functionally important regions of proteins, indicating that positive selection can contravene the well-known principle of evolutionary conservation of functionally important regions. This unexpected finding, along with our discovery that positive selection acts on structural clusters, opens previously unexplored strategies for the development of better models of protein evolution. Remarkably, proteins where we detect the strongest evidence of clustering belong to just two functional groups: Components of immune response and metabolic enzymes. This gives a coherent picture of pathogens and xenobiotics as important drivers of adaptive evolution of mammals.

scholarly journals Network and Evolutionary Analysis of Human Epigenetic Regulators to Unravel Disease Associations

Genes ◽  
2020 ◽  
Vol 11 (12) ◽  
pp. 1457
Author(s):  
Shinji Ohsawa ◽  
Toshiaki Umemura ◽  
Tomoyoshi Terada ◽  
Yoshinori Muto
Keyword(s):  
Positive Selection ◽  
Developmental Stages ◽  
Age Distribution ◽  
System Level ◽  
Disease Genes ◽  
Evolutionary Analysis ◽  
Distribution Analysis ◽  
Cancer Disease ◽  
High Tendency ◽  
Epigenetic Regulators

We carried out a system-level analysis of epigenetic regulators (ERs) and detailed the protein–protein interaction (PPI) network characteristics of disease-associated ERs. We found that most diseases associated with ERs can be clustered into two large groups, cancer diseases and developmental diseases. ER genes formed a highly interconnected PPI subnetwork, indicating a high tendency to interact and agglomerate with one another. We used the disease module detection (DIAMOnD) algorithm to expand the PPI subnetworks into a comprehensive cancer disease ER network (CDEN) and developmental disease ER network (DDEN). Using the transcriptome from early mouse developmental stages, we identified the gene co-expression modules significantly enriched for the CDEN and DDEN gene sets, which indicated the stage-dependent roles of ER-related disease genes during early embryonic development. The evolutionary rate and phylogenetic age distribution analysis indicated that the evolution of CDEN and DDEN genes was mostly constrained, and these genes exhibited older evolutionary age. Our analysis of human polymorphism data revealed that genes belonging to DDEN and Seed-DDEN were more likely to show signs of recent positive selection in human history. This finding suggests a potential association between positive selection of ERs and risk of developmental diseases through the mechanism of antagonistic pleiotropy.

scholarly journals GenomegaMap: Within-Species Genome-Wide dN/dS Estimation from over 10,000 Genomes

2020 ◽  
Vol 37 (8) ◽  
pp. 2450-2460 ◽  
Author(s):  
Daniel J Wilson ◽  
Derrick W Crook ◽  
Timothy E A Peto ◽  
A Sarah Walker ◽  
Sarah J Hoosdally ◽  
...  
Keyword(s):  
Protein A ◽  
Large Data ◽  
Large Data Sets ◽  
Data Sets ◽  
Protein Coding ◽  
Dead Box ◽  
Coalescent Simulations ◽  
Genome Wide ◽  
Signature Of Selection ◽  
Signatures Of Selection

Abstract The dN/dS ratio provides evidence of adaptation or functional constraint in protein-coding genes by quantifying the relative excess or deficit of amino acid-replacing versus silent nucleotide variation. Inexpensive sequencing promises a better understanding of parameters, such as dN/dS, but analyzing very large data sets poses a major statistical challenge. Here, I introduce genomegaMap for estimating within-species genome-wide variation in dN/dS, and I apply it to 3,979 genes across 10,209 tuberculosis genomes to characterize the selection pressures shaping this global pathogen. GenomegaMap is a phylogeny-free method that addresses two major problems with existing approaches: 1) It is fast no matter how large the sample size and 2) it is robust to recombination, which causes phylogenetic methods to report artefactual signals of adaptation. GenomegaMap uses population genetics theory to approximate the distribution of allele frequencies under general, parent-dependent mutation models. Coalescent simulations show that substitution parameters are well estimated even when genomegaMap’s simplifying assumption of independence among sites is violated. I demonstrate the ability of genomegaMap to detect genuine signatures of selection at antimicrobial resistance-conferring substitutions in Mycobacterium tuberculosis and describe a novel signature of selection in the cold-shock DEAD-box protein A gene deaD/csdA. The genomegaMap approach helps accelerate the exploitation of big data for gaining new insights into evolution within species.

scholarly journals Characterizing the Diverse Mutational Pathways Associated with R5-Tropic Maraviroc Resistance: HIV-1 That Uses the Drug-Bound CCR5 Coreceptor

2015 ◽  
Vol 89 (22) ◽  
pp. 11457-11472 ◽  
Author(s):  
Xiaowei Jiang ◽  
Felix Feyertag ◽  
Conor J. Meehan ◽  
Grace P. McCormack ◽  
Simon A. Travers ◽  
...  
Keyword(s):  
Clinical Trials ◽  
Treatment Failure ◽  
Positive Selection ◽  
Antiretroviral Drugs ◽  
Viral Population ◽  
Cell Protein ◽  
V3 Loop ◽  
Evolutionary Analysis ◽  
Resistance Pathway ◽  
Hiv 1

ABSTRACTEntry inhibitors represent a potent class of antiretroviral drugs that target a host cell protein, CCR5, an HIV-1 entry coreceptor, and not viral protein. Lack of sensitivity can occur due to preexisting virus that uses the CXCR4 coreceptor, while true resistance occurs through viral adaptation to use a drug-bound CCR5 coreceptor. To understand this R5 resistance pathway, we analyzed >500 envelope protein sequences and phenotypes from viruses of 20 patients from the clinical trials MOTIVATE 1 and 2, in which treatment-experienced patients received maraviroc plus optimized background therapy. The resistant viral population was phylogenetically distinct and associated with a genetic bottleneck in each patient, consistent withde novoemergence of resistance. Recombination analysis showed that the C2-V3-C3 region tends to genotypically correspond to the recombinant's phenotype, indicating its primary importance in conferring resistance. Between patients, there was a notable lack of commonality in the specific sites conferring resistance, confirming the unusual nature of R5-tropic resistance. We used coevolutionary and positive-selection analyses to characterize the genotypic determinants of resistance and found that (i) there are complicated covariation networks, indicating frequent coevolutionary/compensatory changes in the context of protein structure; (ii) covarying sites under positive selection are enriched in resistant viruses; (iii) CD4 binding sites form part of a unique covariation network independent of the V3 loop; and (iv) the covariation network formed between the V3 loop and other regions of gp120 and gp41 intersects sites involved in glycosylation and protein secretion. These results demonstrate that while envelope sequence mutations are the key to conferring maraviroc resistance, the specific changes involved are context dependent and thus inherently unpredictable.IMPORTANCEThe entry inhibitor drug maraviroc makes the cell coreceptor CCR5 unavailable for use by HIV-1 and is now used in combination antiretroviral therapy. Treatment failure with drug-resistant virus is particularly interesting because it tends to be rare, with lack of sensitivity usually associated with the presence of CXCR4-using virus (CXCR4 is the main alternative coreceptor HIV-1 uses, in addition to CD4). We analyzed envelope sequences from HIV-1, obtained from 20 patients who enrolled in maraviroc clinical trials and experienced treatment failure, without detection of CXCR4-using virus. Evolutionary analysis was employed to identify molecular changes that confer maraviroc resistance. We found that in these individuals, resistant viruses form a distinct population that evolved once and was successful as a result of drug pressure. Further evolutionary analysis placed the complex network of interdependent mutational changes into functional groups that help explain the impediments to the emergence of maraviroc-associated R5 drug resistance.

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