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Phenotypic evolution from genetic polymorphisms in a radial network architecture.

ABSTRACT: BACKGROUND:The genetic architecture of a quantitative trait influences the phenotypic response to natural or artificial selection. One of the main objectives of genetic mapping studies is to identify the genetic factors underlying complex traits and understand how they contribute to phenotypic expression. Presently, we are good at identifying and locating individual loci with large effects, but there is a void in describing more complex genetic architectures. Although large networks of connected genes have been reported, there is an almost complete lack of information on how polymorphisms in these networks contribute to phenotypic variation and change. To date, most of our understanding comes from theoretical, model-based studies, and it remains difficult to assess how realistic their conclusions are as they lack empirical support. RESULTS:A previous study provided evidence that nearly half of the difference in eight-week body weight between two divergently selected lines of chickens was a result of four loci organized in a 'radial' network (one central locus interacting with three 'radial' loci that, in turn, only interacted with the central locus). Here, we study the relationship between phenotypic change and genetic polymorphism in this empirically detected network. We use a model-free approach to study, through individual-based simulations, the dynamic properties of this polymorphic and epistatic genetic architecture. The study provides new insights to how epistasis can modify the selection response, buffer and reveal effects of major loci leading to a progressive release of genetic variation. We also illustrate the difficulty of predicting genetic architecture from observed selection response, and discuss mechanisms that might lead to misleading conclusions on underlying genetic architectures from quantitative trait locus (QTL) experiments in selected populations. CONCLUSION:Considering both molecular (QTL) and phenotypic (selection response) data, as suggested in this work, provides additional insights into the genetic mechanisms involved in the response to selection. Such dissection of genetic architectures and in-depth studies of their ability to contribute to short- or long-term selection response represents an important step towards a better understanding of the genetic bases of complex traits and, consequently, of the evolutionary properties of populations.

SUBMITTER: Le Rouzic A

PROVIDER: S-EPMC2194667 | biostudies-literature | 2007 Nov

REPOSITORIES: biostudies-literature

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Phenotypic evolution from genetic polymorphisms in a radial network architecture.

Le Rouzic Arnaud A Siegel Paul B PB Carlborg Orjan O

BMC biology 20071114

<h4>Background</h4>The genetic architecture of a quantitative trait influences the phenotypic response to natural or artificial selection. One of the main objectives of genetic mapping studies is to identify the genetic factors underlying complex traits and understand how they contribute to phenotypic expression. Presently, we are good at identifying and locating individual loci with large effects, but there is a void in describing more complex genetic architectures. Although large networks of c ...[more]

PMID: 18001473

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Project description:Chromatin accessibility is an important functional genomics phenotype that influences transcription factor binding and gene expression. Genome-scale technologies allow chromatin accessibility to be mapped with high-resolution, facilitating detailed analyses into the genetic architecture and evolution of chromatin structure within and between species. We performed Formaldehyde-Assisted Isolation of Regulatory Elements sequencing (FAIRE-Seq) to map chromatin accessibility in two parental haploid yeast species, Saccharomyces cerevisiae and Saccharomyces paradoxus and their diploid hybrid. We show that although broad-scale characteristics of the chromatin landscape are well conserved between these species, accessibility is significantly different for 947 regions upstream of genes that are enriched for GO terms such as intracellular transport and protein localization exhibit. We also develop new statistical methods to investigate the genetic architecture of variation in chromatin accessibility between species, and find that cis effects are more common and of greater magnitude than trans effects. Interestingly, we find that cis and trans effects at individual genes are often negatively correlated, suggesting widespread compensatory evolution to stabilize levels of chromatin accessibility. Finally, we demonstrate that the relationship between chromatin accessibility and gene expression levels is complex, and a significant proportion of differences in chromatin accessibility might be functionally benign. There are 20 samples in total. These consist of 10 FAIRE-seq samples, specifically 6 haploid samples, S. cerevisiae strain UWOPS05_217_3 replicates 1 and 2, S. cerevisiae strain DBVPG1373 replicates 1 and 2, and S. paradoxus strain CBS432 replicates 1 and 2. There are also 4 diploid hybrid samples, hybrid between S. cerevisiae strain UWOPS05_217_3 and S. paradoxus strain CBS432 replicates 1 and 2, and the hybrid between S. cerevisiae strain DBVPG1373 and S. paradoxus strain CBS432 replicates 1 and 2. There are also RNA-seq samples for each of these 10 samples.

Dataset Information

Phenotypic evolution from genetic polymorphisms in a radial network architecture.

Publications

Phenotypic evolution from genetic polymorphisms in a radial network architecture.

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