scholarly journals Drift and directional selection are the evolutionary forces driving gene expression divergence in eye and brain tissue ofHeliconiusbutterflies

2018 ◽  
Author(s):  
Ana Catalán ◽  
Adriana Briscoe ◽  
Sebastian Höhna
Keyword(s):  
Gene Expression ◽  
Brownian Motion ◽  
Brain Tissue ◽  
Directional Selection ◽  
Stabilizing Selection ◽  
Expression Levels ◽  
Evolutionary Forces ◽  
Expression Evolution ◽  
Species Specific ◽  
Gene Expression Evolution

AbstractInvestigating gene expression evolution over micro- and macroevolutionary timescales will expand our understanding of the role of gene expression in adaptation and speciation. In this study, we characterized which evolutionary forces are acting on gene expression levels in eye and brain tissue of fiveHeliconiusbutterflies with divergence times of ~5-12 MYA. We developed and applied Brownian motion and Ornstein-Uhlenbeck models to identify genes whose expression levels are evolving through drift, stabilizing selection, or a lineage-specific shift. We find that 81% of the genes evolve under genetic drift. When testing for branch-specific shifts in gene expression, we detected 368 (16%) shift events. Genes showing a shift towards up-regulation have significantly lower gene expression variance than those genes showing a shift leading towards down-regulation. We hypothesize that directional selection is acting in shifts causing up-regulation, since transcription is costly. We further uncover through simulations that parameter estimation of Ornstein-Uhlenbeck models is biased when using small phylogenies and only becomes reliable with phylogenies having at least 50 taxa. Therefore, we developed a new statistical test based on Brownian motion to identify highly conserved genes (i.e., evolving under strong stabilizing selection), which comprised 3% of the orthoclusters. In conclusion, we found that drift is the dominant evolutionary force driving gene expression evolution in eye and brain tissue inHeliconius. Nevertheless, the higher proportion of genes evolving under directional than under stabilizing selection might reflect species-specific selective pressures on vision and brain necessary to fulfill species-specific requirements.

scholarly journals High rates of evolution preceded shifts to sex-biased gene expression in Leucadendron, the most sexually dimorphic angiosperms

2021 ◽  
Author(s):  
Mathias Scharmann ◽  
Anthony G Rebelo ◽  
John R Pannell
Keyword(s):  
Gene Expression ◽  
Sexual Dimorphism ◽  
Rapid Evolution ◽  
Sex Bias ◽  
Sexually Dimorphic ◽  
Expression Levels ◽  
Rates Of Evolution ◽  
Expression Evolution ◽  
Males And Females ◽  
Species Specific

AbstractThe males and females of many dioecious plants differ in morphological (Dawson and Geber 1999; Barrett and Hough 2013; Tonnabel et al. 2017), physiological (Juvany and Munné-Bosch 2015), life-history (Delph 1999), and defence traits (Cornelissen and Stiling 2005). Ultimately, such sexual dimorphism must largely be due to differential gene expression between the sexes (Ellegren and Parsch 2007), but little is known about how sex-biased genes are recruited and how their expression evolves over time. We measured gene expression in leaves of males and females of ten species sampled across the South African Cape genus Leucadendron, which shows repeated changes in sexual dimorphism and includes the most extreme differences between males and females in flowering plants (Midgley 2010; Barrett and Hough 2013; Tonnabel et al. 2014). Even in the most dimorphic species in our sample, fewer than 2% of genes showed sex-biased gene expression (SBGE) in vegetative tissue, with surprisingly little correspondence between SBGE and vegetative dimorphism across species. The identity of sex-biased genes in Leucadendron was highly species-specific, with a rapid turnover among species. In animals, sex-biased genes often evolve more quickly than unbiased genes in their sequences and expression levels (Ranz et al. 2003; Khaitovich et al. 2005; Ellegren and Parsch 2007; Voolstra et al. 2007; Harrison et al. 2015; Naqvi et al. 2019), consistent with hypotheses invoking rapid evolution due to sexual selection. Our phylogenetic analysis in Leucadendron, however, clearly indicates that sex-biased genes are recruited from a class of genes with ancestrally rapid rates of expression evolution, perhaps due to low evolutionary or pleiotropic constraints. Nevertheless, we also find evidence for adaptive evolution of expression levels once sex bias evolves. Thus, although the expression of sex-biased genes is ultimately responsive to selection, high rates of expression evolution might usually predate the evolution of sex bias.

scholarly journals Intra- and inter-specific variations of gene expression levels in yeast are largely neutral

2016 ◽  
Author(s):  
Jian-Rong Yang ◽  
Calum Maclean ◽  
Chungoo Park ◽  
Huabin Zhao ◽  
Jianzhi Zhang
Keyword(s):  
Gene Expression ◽  
Genome Sequence ◽  
Large Fraction ◽  
General Role ◽  
Expression Levels ◽  
Genome Wide ◽  
Sequence Variations ◽  
Expression Evolution ◽  
Molecular Phenotypes ◽  
Gene Expression Levels

ABSTRACTIt is commonly, although not universally, accepted that most intra- and inter-specific genome sequence variations are more or less neutral, whereas a large fraction of organism-level phenotypic variations are adaptive. Gene expression levels are molecular phenotypes that bridge the gap between genotypes and corresponding organism-level phenotypes. Yet, it is unknown whether natural variations in gene expression levels are mostly neutral or adaptive. Here we address this fundamental question by genome-wide profiling and comparison of gene expression levels in nine yeast strains belonging to three closely related Saccharomyces species and originating from five different ecological environments. We find that the transcriptome-based clustering of the nine strains approximates the genome sequence-based phylogeny irrespective of their ecological environments. Remarkably, only ∼0.5% of genes exhibit similar expression levels among strains from a common ecological environment, no greater than that among strains with comparable phylogenetic relationships but different environments. These and other observations strongly suggest that most intra- and inter-specific variations in yeast gene expression levels result from the accumulation of random mutations rather than environmental adaptations. This finding has profound implications for understanding the driving force of gene expression evolution, genetic basis of phenotypic adaptation, and general role of stochasticity in evolution.

scholarly journals Relating gene expression evolution with CpG content changes

BMC Genomics ◽  
2014 ◽  
Vol 15 (1) ◽  
pp. 693 ◽  
Author(s):  
Huan Yang ◽  
Dawei Li ◽  
Chao Cheng
Keyword(s):  
Gene Expression ◽  
Expression Evolution ◽  
Gene Expression Evolution

scholarly journals Evolution of H3K27me3-marked chromatin is linked to gene expression evolution and to patterns of gene duplication and diversification

2014 ◽  
Vol 24 (7) ◽  
pp. 1115-1124 ◽  
Author(s):  
R. K. Arthur ◽  
L. Ma ◽  
M. Slattery ◽  
R. F. Spokony ◽  
A. Ostapenko ◽  
...  
Keyword(s):  
Gene Expression ◽  
Gene Duplication ◽  
Expression Evolution ◽  
Gene Expression Evolution

scholarly journals On the relation between promoter divergence and gene expression evolution

2008 ◽  
Vol 4 (1) ◽  
pp. 159 ◽  
Author(s):  
Itay Tirosh ◽  
Adina Weinberger ◽  
Dana Bezalel ◽  
Mark Kaganovich ◽  
Naama Barkai
Keyword(s):  
Gene Expression ◽  
Expression Evolution ◽  
Gene Expression Evolution ◽  
Promoter Divergence

scholarly journals Modeling gene expression evolution with EvoGeneX uncovers differences in evolution of species, organs and sexes

2020 ◽  
Author(s):  
Soumitra Pal ◽  
Brian Oliver ◽  
Teresa M. Przytycka
Keyword(s):  
Gene Expression ◽  
Evolutionary Dynamics ◽  
Computational Method ◽  
Specific Gene ◽  
Species Variation ◽  
Evolutionary Divergence ◽  
Sequence Evolution ◽  
Study Gene Expression ◽  
Expression Evolution ◽  
Gene Expression Evolution

AbstractWhile DNA sequence evolution has been well studied, the expression of genes is also subject to evolution. Yet the evolution of gene expression is currently not well understood. In recent years, new tissue/organ specific gene expression datasets spanning several organisms across the tree of life, have become available providing the opportunity to study gene expression evolution in more detail. However, while a theoretical model to study evolution of continuous traits exist, in practice computational methods often cannot distinguish, with confidence, between alternative evolutionary scenarios. This lack of power has been attributed to the modest number of species with available expression data.To solve this challenge, we introduce EvoGeneX, a computationally efficient method to uncover the mode of gene expression evolution based on the Ornstein-Uhlenbeck process. Importantly, EvoGeneX in addition to modelling expression variations between species, models within species variation. To estimate the within species variation, EvoGeneX formally incorporates the data from biological replicates as a part of the mathematical model. We show that by modelling the within species diversity EvoGeneX significantly outperforms the currently available computational method. In addition, to facilitate comparative analysis of gene expression evolution, we introduce a new approach to measure the dynamics of evolutionary divergence of a group of genes.We used EvoGeneX to analyse the evolution of expression across different organs, species and sexes of the Drosophila genus. Our analysis revealed differences in the evolutionary dynamics of male and female gonads, and uncovered examples of adaptive evolution of genes expressed in the head and in the thorax.

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