This research intends to determine the importance of genetic variation in the two separate genomes that occur in all animal cells: the nuclear and mitochondrial genomes. These genomes work together to form the enzymes in one metabolic pathway, the Oxidative Phosphorylation metabolic pathway. The Oxidative Phosphorylation pathway makes the vast majority of ATP energy produced in animals breathing oxygen. To investigate the importance of genetic variation in this pathway, the research goals include 1) determining the sequencing variation among all the genes in the oxidative phosphorylation pathway, (2) quantifying the differences in RNA expression for these genes, and (3) determining the functional and biochemical consequences of both protein polymorphisms and gene expression. To understand the naturally occurring genetic differences, this research uses evolutionary analyses of the two genomes among populations of the salt marsh minnow, F. heteroclitus, that are distributed along a steep thermal cline where southern populations are >12°C warmer than northern populations. This clinal variation in temperature is associated with adaptive changes in enzyme kinetics and enzyme expression. This approach integrates the physiological effects of temperature on protein variants, nucleotide polymorphisms and quantitative variation in RNA expression, and defines biologically important differences by defining changes that have evolved by natural selection (i.e., are evolutionary adaptations). Combining the discovery of nucleotide variation, quantitative variation in RNA expression, and the functional consequences of this variation will enhance our understanding of the evolution of two genomes and how constraints and conflict within and between genomes affect evolutionary processes. By analyzing a complete metabolic pathway, we will gain a broad understanding of how adaptive evolution affects changes among many interacting genes to achieve adaptive physiological changes. Thus, these data provide a unique perspective of how global warming may affect the physiology and evolution of animals.
Broader Impacts: This research will enhance undergraduate and graduate student training and education in scientific research using DNA sequencing, biochemistry and physiology. To enhance the participation of under-represented groups, minority undergraduates will be recruited through our interactions with science programs that are geared for minorities at the University of Miami. Additionally, society and the science community will benefit from the empirical data on the relationship between changing thermal environments and nucleotide variation across many whole mitochondrial genomes. These data, which will be publically available, will provide a rich database for the Fundulus research community, physiologists working on mitochondrial function, and researchers modeling haploid genome evolution.
