9419631 CLARK This is an experimental and theoretical study of variation in biochemical traits that are related through metabolic pathways. The experimental system focuses on the maintenance of lipid and glycogen stores in Drosophila melanogaster. The investigator, Dr. Andrew Clark will quantify lipid and glycogen storage, along with the activities of 12 enzymes in associated biosynthetic and degradative pathways, to perform large-scale quantitative genetic studies of these traits. There is much theory dealing with enzymes in biochemical pathways. An objective is to develop the evolutionary genetic aspects of this theory and to test the fit of the theory to the model system of energy storage in Drosophila. The idea that observed levels of phenotypic variation in populations arise from a balance between mutation inflating the variance and stabilizing selection restricting it has considerable appeal. But attempts to estimate the necessary parameters have revealed discrepancies. Theoreticians have shifted their focus toward pleiotropic effects of mutations as a possible explanation for heritable variation, and this experimental system is well-suited to test these ideas.
