Mutational variance of the transcriptome and the origins of phenotypic plasticity

University Of South Carolina At Columbia, Columbia SC

Investigators

Abstract

This research seeks to determine how often genetic mutations occur, whether they produce a change in how gene activity levels respond to the environment, and whether those altered responses have effects on observable traits. This study will provide insight into how genetic differences among organisms arise, the basis for all evolutionary change and the diversity of life. Differences among organisms are driven, in part, by differences in their genes and differences in the rate at which genetic information is used for the building of proteins and other cell structures, the activity of those genes. Genetic differences arise due to errors made when copying DNA, the molecule in which genetic information is stored. If these errors happen during cell divisions that lead to an individual's offspring, the differences will be inherited by all future generations. A parallel educational activity will develop a computer-based application that simulates copying errors in the context of music. When students learn genetics, they often begin with several misconceptions about mutations. However, realistic experiments illustrating properties of mutations are difficult to execute in class settings. Therefore, the project includes development of "Mutational Music", an application for mobile devices that uses computer-based music to simulate spontaneous mutations, along with an educational program appropriate for use in introductory genetics laboratories. Spontaneous mutations are the ultimate source of genetic variation; understanding their characteristics is therefore a fundamental goal of biologists. Existing work has quantified the rate and effects of spontaneous mutations, usually focusing on the molecular spectrum of mutations or on fitness effects. These foci are widely separated, and the processes that link molecular mutations to fitness effects have received less attention. This project is aimed at bridging the gap between fitness and the molecular spectrum of mutations, focusing on mutational changes in the transcriptome and in phenotypic plasticity of key life history traits. The research involves a mutation accumulation experiment in the model crustacean Daphnia pulex, coupled with analyses of gene expression and life history traits made in distinct resource environments. The work will generate estimates of the mutational variance and heritability of expression for each gene, including the ability to identify allele-specificity and splice variant-specificity. In addition, the work will quantify the distribution of effects spontaneous mutations have on life history traits and their plasticity. The components will be joined to investigate the potential that expression mutations contribute to the origin of phenotypic plasticity.