The fish Fundulus heteroclitus is widely distributed in estuaries along the eastern seacoast of North America. This species is found in areas where there is considerable variation in habitat spatial heterogeneity (i.e., landscape complexity) and in a region characterized by one of the world's steepest thermal clines: approximately 1.0 degree centigrade per degree of latitude. The goals of this project are to determine how landscape complexity within a local region and along the steep thermal cline affect genome-wide patterns of gene expression. Landscape structure is hypothesized to affect population size and genetic structure, and individual growth rates, longevity, and migration. These parameters in turn alter the process of natural selection and thus affect an organism's ability to adapt to local conditions. This project will measure these ecological and population variables and explore their relationships to patterns of gene expression. Genetic crosses of field-collected populations, and laboratory acclimation of their progeny, will determine if physiological induction or heritable genetic differences are responsible for the differences in gene expression. Genome-wide patterns of mRNA expression will be quantified with F. heteroclitus microarrays. Because variation in messenger RNA must be translated into changes in protein concentration to produce a phenotypic change, microarray experiments will be complemented by high-throughput analyses of protein expression (proteomics). If variation in gene expression is one of the most important adaptive mechanisms, this project will detect significant differences in gene expression associated with differences in landscape and thermal ecology. This research will determine how ecological factors operating at diverse geographic scales affect the population biology and gene expression of F. heteroclitus.
