Title

The development and use of microsatellite DNA markers from Fundulus heteroclitus as a method of measuring genetic diversity and ecological impact in polluted areas of Long Island Sound

Date of Completion

January 2005

Keywords

Biology, Ecology|Biology, Genetics|Biology, Microbiology|Engineering, Environmental

Degree

Ph.D.

Abstract

The fish Fundulus heteroclitus has been established as a sentinel species for study of anthropogenic impact on coastal and estuarine aquatic systems. Fish collected from subpopulations resident in polluted aquatic systems are known to display altered survivability and gene induction when compared to fish from less impacted areas. It has been indicated that the alterations in survival and gene expression in impacted subpopulations are due to genetically based heritable traits, maintained in the populations by strong selective pressure. In this study F. heteroclitus from eight sites along the Connecticut shoreline of Long Island Sound (LIS) were examined at seven novel microsatellite loci in order to determine the population structure and genetic diversity. The study sites used in this work represent a broad range of anthropogenic impacts on the ecosystems, including moderate to high levels of PCBs, PAHs, and other known xenobiotics. It was hypothesized that subpopulations resident to more polluted areas would be reproductively isolated and genetically distinct from nearby populations under less selective pressure. It was observed that the population structure in LIS consists of highly fragmented and reproductively isolated subpopulations. It was further observed that many of the subpopulations were fragmented in discrete mating groups. The subpopulation structure is indicative of genetic isolation between nearby subpopulations. Pair-wise genetic distances and F ST estimates examined relative to geographic sampling position reveal significant genetic differences that cannot be explained by the geographic cline. It is concluded that several of the populations are under strong selective pressure from other environmental factors. It is currently believed that the most likely factors involved in Long Island Sound are anthropogenic in nature due to the heavy industrialization of the watershed and the significant soil and water contamination. ^