Project description:This set of arrays contains all microarray experiments done involving comparisons among C. elegans natural isolates and mutation-accumulation lines. Abstract: The evolutionary importance of gene-expression divergence is unclear: some studies suggest that it is an important mechanism for evolution by natural selection, whereas others claim that most between-species regulatory changes are neutral or nearly neutral. We examined global transcriptional divergence patterns in a set of Caenorhabditis elegans mutation-accumulation lines and natural isolate lines to provide insights into the evolutionary importance of transcriptional variation and to discriminate between the forces of mutation and natural selection in shaping the evolution of gene expression. We detected the effects of selection on transcriptional divergence patterns and characterized them with respect to coexpressed gene sets, chromosomal clustering of expression changes and functional gene categories. We directly compared observed transcriptional variation patterns in the mutation-accumulation and natural isolate lines to a neutral model of transcriptome evolution to show that strong stabilizing selection dominates the evolution of transcriptional change for thousands of C. elegans expressed sequences. An all pairs experiment design type is where all labeled extracts are compared to every other labeled extract. Computed
Project description:This set of arrays contains all microarray experiments done involving comparisons among C. elegans natural isolates and mutation-accumulation lines. Abstract: The evolutionary importance of gene-expression divergence is unclear: some studies suggest that it is an important mechanism for evolution by natural selection, whereas others claim that most between-species regulatory changes are neutral or nearly neutral. We examined global transcriptional divergence patterns in a set of Caenorhabditis elegans mutation-accumulation lines and natural isolate lines to provide insights into the evolutionary importance of transcriptional variation and to discriminate between the forces of mutation and natural selection in shaping the evolution of gene expression. We detected the effects of selection on transcriptional divergence patterns and characterized them with respect to coexpressed gene sets, chromosomal clustering of expression changes and functional gene categories. We directly compared observed transcriptional variation patterns in the mutation-accumulation and natural isolate lines to a neutral model of transcriptome evolution to show that strong stabilizing selection dominates the evolution of transcriptional change for thousands of C. elegans expressed sequences. An all pairs experiment design type is where all labeled extracts are compared to every other labeled extract. Keywords: all_pairs
Project description:Transcript abundance was measured in whole-body virgin male Drosophila serrata from 41 inbred lines that had diverged through 27 generations of mutation accumulation. Pleiotropic mutations are the ultimate source of genetic variation in complex traits, including many human diseases. However, the nature and extent of mutational pleiotropy remain largely unknown. Here, we investigate the variation in 11,604 gene expression traits among 41 mutation accumulation lines of Drosophila serrata, which had diverged for 27 generations. We detected significant mutational variance in 4.6% of ESTs, but 70% of ESTs were invariant among lines, allowing us to reject a null hypothesis of phenome-wide universal pleiotropy. Mutational covariance among ESTs was detected at a frequency of only 1 in 193 random pairs of variable EST, bu t was detected among random combinations of five ESTs in 1 in 5 cases, revealing that mutational covariance among multiple ESTs was common. The observed frequency of significant multivariate covariance among random ESTs implied that a substantial number of ESTs (>70) must be pleiotropically affected by at least some mutations. We measured gene expression of male Drosophila serrata from 41 mutation accumulation lines (whole-body). Data from two replicates for each line are presented.
Project description:Mutation generates the heritable variation that genetic drift and natural selection shape. In classical quantitative genetic models, drift is a function of the effective population size and acts uniformly across traits, while mutation and selection act trait-specifically. We identified thousands of quantitative trait loci (QTL) influencing transcript abundance traits in a cross of two C. elegans strains; although trait-specific mutation and selection explained some of the observed pattern of QTL distribution, the pattern was better explained by trait-independent variation in the intensity of selection on linked sites. Our results suggest that traits in C. elegans exhibit different levels of variation less because of their own attributes than because of differences in the effective population sizes of the genomic regions harboring their underlying loci.
Project description:Transcript abundance was measured in whole-body virgin male Drosophila serrata from 41 inbred lines that had diverged through 27 generations of mutation accumulation. Pleiotropic mutations are the ultimate source of genetic variation in complex traits, including many human diseases. However, the nature and extent of mutational pleiotropy remain largely unknown. Here, we investigate the variation in 11,604 gene expression traits among 41 mutation accumulation lines of Drosophila serrata, which had diverged for 27 generations. We detected significant mutational variance in 4.6% of ESTs, but 70% of ESTs were invariant among lines, allowing us to reject a null hypothesis of phenome-wide universal pleiotropy. Mutational covariance among ESTs was detected at a frequency of only 1 in 193 random pairs of variable EST, bu t was detected among random combinations of five ESTs in 1 in 5 cases, revealing that mutational covariance among multiple ESTs was common. The observed frequency of significant multivariate covariance among random ESTs implied that a substantial number of ESTs (>70) must be pleiotropically affected by at least some mutations.
Project description:Transcript abundance was measured in whole-body virgin male Drosophila serrata from 41 inbred lines that had diverged through 27 generations of mutation accumulation that were sexually selected Sexual selection is predicted to have widespread effects on the genetic variation generated by new mutations as a consequence of the genic capture of condition by male sexual traits. We manipulated the opportunity for sexual selection on males during 27 generations of mutation accumulation in inbred lines of Drosophila serrata, and used a microarray platform to investigate the effect of sexual selection on the expression of 2685 genes, representing a broad coverage of biological function. Sexual selection had little effect on mean gene expression levels, with only 4 genes diverging significantly at a false discovery rate of 5% . In contrast, sexual selection impacted on both the magnitude and nature of mutational variance accumulating in these genes. The magnitude of mutational variance increased under sexual selection by an average of 29%. Mutational variance was less commonly generated by extreme phenotypes less commonly under sexual selection. Furthermore, analysis of random sets of five genes revealed that the mutational variance that accumulated under sexual selection was less pleiotropic in nature than that found in the absence of sexual selection. The generation of greater mutational variance without a general concomitant change in mean expression under sexual selection suggested that gene expression traits were be under apparent rather than direct sexual selection. We discuss two main explanations for the broad-based increase in mutational variance under sexual selection that both require extensive pleiotropy between traits affecting male mating success, standard metric traits represented here by gene expression traits, and general fitness. We measured gene expression of male Drosophila serrata from 41 mutation accumulation lines (whole-body) that were sexually selected. Data from two replicates for each line are presented.