G-matrix; pleiotropy; modularity; evolution; natural selection; gene flow; genotype-phenotype map; local adaptation; quantitative character; modeling
Polster Robert and Petropoulos Christos J. and Bonhoeffer Sebastian and Guillaume Frédéric (2016), Epistasis and pleiotropy affect the modularity of the genotype-phenotype map of cross-resistance in HIV-1, in Molecular Biology and Evolution
, 33(12), 3213-3225.
Kremer A., Ronce O., Robledo-Arnuncio J.J., Guillaume F., Bohrer G., Nathan R., Bridle J.R., Gomulkiewicz R., Klein E., Ritland K., Kuparinen A., Gerber S., Schueler S. (2012), Long-distance gene flow and adaptation of forest trees to rapid climate changes, in Ecology Letters
, 15(4), 378-392.
Zhang H., Guillaume F., Engelstädter J. (2012), The dynamics of mitochondrial mutations causing male infertility in spatially structured populations, in Evolution
, 0, 0-0.
Guillaume Frédéric (2011), Migration-induced phenotypic divergence: the migration-selection balance of correlated traits, in Evolution
, 65(6), 1723-1738.
Yeaman Sam, Guillaume Frédéric (2009), Predicting adaptation under migration load: the role of genetic skew, in Evolution
, 63(11), 2926-2938.
Whitlock Michael C., Guillaume Frederic (2009), Testing for spatially divergent selection: comparing QST to FST, in Genetics
, 183(3), 1055-1063.
In this project, I am asking the question of how does the genetic architecture of complex traits affect their evolution in the context of adaptive evolution in structured populations. The genetic architecture of a trait can be understood as the amount of genetic variance available for that trait to evolve, or its heritability, and the way it co-varies with the other traits that determine the complex set of phenotypic characters upon which selection acts. The genetic variances and covariances of the traits under study in a population are generally summarized by a matrix, the genetic variance-covariance matrix or G-matrix. The multivariate response to selection of a population is given by the product of G and ß, the selection gradient (Lande 1979). Therefore, the main effect of the existence of genetic covariances between the traits is to divert the evolution of the population from its optimal path toward its phenotypic optimum, represented by ß. This project proposes to study the joint effects of the genetic architecture of quantitative traits and population structure on the evolution of the G-matrix. Both are predicted to deeply influence the evolution of the structure of the G-matrix because the variation in genetic variances and covariances of the traits has its source in allelic frequencies variations due both to the effect of population structure on evolutionary processes and to the variation in the pleiotropic effects of the genes coding for the traits. G thus summarizes both effects and helps predict their joint influence on the adaptive evolution of species.I will further seek to model the genetic architecture of phenotypic characters based on the information we have from model organisms (e.g. yeast, mouse, or stickleback) on the precise genetic basis of such traits. The genetic properties I will search for in these empirical datasets are the distribution of pleiotropic effects and the extent of modularity of the genotype-phenotype map (the g-p map). Modularity represents how the pleiotropic effects of the genes cluster together to affect only a subset of traits. Modular traits are thus thought to be able to independently respond to selection whereas integrated traits are more constrained. Higher modularity is predicted to increase the rate of adaptation under certain circumstances. I will thus test whether modularity is correlated with the rate of evolution of the genes in the datasets available. I will develop a way to characterise that modularity of the g-p map, and, by integrating this real-world information into the simulation model, I will investigate the effects of the precise structure of the g-p map on the structure of the G-matrix and on adaptive evolution in structured populations.Finally, I will ask the question of how does the genetic architecture of complex traits evolve, or how does modularity of the g-p map emerge as a result of adaptive evolution of complex phenotypic traits? Very little is known about the selective pressures acting on the pleiotropy of the genes underlying complex phenotypes. I will thus develop a model of the evolution of pleiotropy that allows me to predict the distribution of pleiotropic effects as well as understand the selective pressures acting on the evolution of pleiotropy. Such an approach is awaited as it may lead to testable predictions such as what ecological opportunities are needed to favour the evolution of a modular structure in the genetic architecture of the phenotype. This project will thus be an attempt to fill a gap in our knowledge of the evolution of the genetic architecture of quantitative traits and to show how emergent properties of complex phenotypes, such as robustness (canalization), and evolvability, may evolve. The approach chosen will be a combination of individual-based and genetically explicit computer simulations, domain where I have most experience, and statistical analyses for the development of comparative and descriptive tools for the study of the G-matrix and the modularity of the genotype-phenotype map.