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FINE-SCALE GENETIC DIFFERENTIATION BETWEEN CONTAMINANT-TOLERANT AND CONTAMINANT SENSITIVE FISH POPULATIONS
Citation:
McMillan, A., M Bagley, D E. Nacci, AND S Christ. FINE-SCALE GENETIC DIFFERENTIATION BETWEEN CONTAMINANT-TOLERANT AND CONTAMINANT SENSITIVE FISH POPULATIONS. Presented at The Annual Meeting of the Society of Environmental Toxicology and Chemistry, Nashville, TN, November 12-16, 2000.
Description:
Studies have suggested that environmental contaminants can act as selective forces on exposed populations of wildlife species. Chronically exposed populations have shown reduced genetic diversity and/or demonstrated other genetic changes. We evaluated the genetic structure of populations of Fundulus heteroclitus, a non-migratory fish found in abundance in eastern U.S. estuaries, including a PCB-contaminated Superfund site in New Bedford Harbor (NBH), MA. Laboratory challenge experiments indicated that F. heteroclitus from NBH are adapted to high PCB levels unlike fish at nearby uncontaminated sites. These results suggest strong divergence has occurred in response to recent anthropogenic changes, and has been maintained among populations with potentially high gene flow. To test this hypothesis we used amplified fragment length polymorphism (AFLP) analysis, a multilocus DNA fingerprinting method, to characterize the genetic structure of F. heteroclitus populations residing in and around NBH. The AFLP methodology allows rapid assessment of genetic variation for hundreds of independent, neutral DNA markers and is expected to provide the resolution needed to assess genetic differentiation of F: heteroclitus populations over small geographic scales. This work will nicely complement related efforts to study diversity at protein-coding loci. Specifically, the goals of this study are (1) to determine whether genetic variability of tolerant F. heteroclitus populations in NBH is reduced relative to populations in less contaminated sites and (2) to estimate the degree of genetic differentiation between F. heteroclitus populations with different sensitivities to PCBs. Results of this research will help explain circumstances under which organisms can adapt to contaminated environments and will improve our ability to predict how anthropogenic stressors and species characteristics interact to produce evolutionary effects.