Quantitative Genetics

Evolution of the G-matrix and Adaptive Landscapes

My interest in sexual selection possesses a natural connection to an interest in selection in general. Selection theory is as important to sexually selected traits as it is to naturally selected traits. I have thus recently become interested in some fundamental topics in quantitative genetics. So far, our studies have focused on one of these topics, the issue of stability of the genetic variance-covariance matrix.

G-matrix Stability and Evolutionary Inference

Stevan Arnold, Reinhard Bürger, and I have been using simulation-based quantitative genetic models to investigate the stability of the G-matrix in evolving populations. The G-matrix is the genetic variance-covariance matrix for a suite of traits. For a phenotype composed of multiple traits, the response to selection is determined by the intensity of selection as well as by the G-matrix. Thus, knowledge of the G-matrix is required to predict the response to selection or to reconstruct the history of selection. An unstable G-matrix would render these goals impossible over many generations, because contemporary estimates of the G-matrix would not be relevant to generations in the distant past or future. Consequently, the issue of G-matrix stability has been the subject of much debate in the quantitative genetics literature. Our results are beginning to define the conditions that favor G-matrix stability and instability.

Arnold, S. J., M. E. Pfrender, and A. G. Jones. 2001. The adaptive landscape as a conceptual bridge between micro- and macro-evolution. Genetica 112/113:9-32.

Jones, A. G., S. J. Arnold, and R. Bürger. 2003. Stability of the G-matrix in a population experiencing stabilizing selection, pleiotropic mutation, and genetic drift. Evolution 57:1747-1760.

Jones, A. G., S. J. Arnold, and R. Bürger. 2004. Evolution and stability of the G-matrix under a moving optimum.  Evolution 58:1639-1654.