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Targeted Approach to Identify Genetic Loci Associated with Evolved Dioxin Tolerance in Atlantic Killifish (Fundulus heteroclitus)
Proestou, D., P. Flight, D. Champlin, AND D. Nacci. Targeted Approach to Identify Genetic Loci Associated with Evolved Dioxin Tolerance in Atlantic Killifish (Fundulus heteroclitus). BMC Evolutionary Biology. BioMed Central Ltd, London, Uk, 14(7):1-31, (2014).
Extreme tolerance to highly toxic dioxin-like contaminants (DLCs) has evolved independently and contemporaneously in (at least) four populations of Atlantic killifish (Fundulus heteroclitus). Surprisingly, the magnitude and phenotype of DLC tolerance is similar among these killifish populations that have adapted to varied, but highly contaminated urban/industrialized estuaries of the US Atlantic coast. We hypothesized that comparisons among tolerant populations and in contrast to their sensitive neighboring killifish might reveal genetic loci associated with DLC tolerance. Since the aryl hydrocarbon receptor (AHR) pathway partly or fully mediates DLC toxicity in vertebrates, we identified single nucleotide polymorphisms (SNPs) from 43 genes associated with the AHR to serve as targeted markers. Wild fish from the four highly tolerant killifish populations and four nearby sensitive populations were genotyped using 59 SNP markers. Consistent with other killifish population genetic analyses, our results revealed strong genetic differentiation among populations, consistent with isolation by distance models. Pairwise comparisons of nearby tolerant and sensitive populations revealed differentiation among these loci: AHR 1 and 2, cathepsin Z, the cytochrome P450s (CYP) 1A and 3A30, and the NADH ubiquinone oxidoreductase MLRQ subunit. By grouping tolerant versus sensitive populations, we also identified cytochrome P450 1A and the AHR2 loci as under selection, lending support to the argument that the CYP1A and/or AHR2 loci may have evolved in populations adapted to extreme DLC contamination.
This manuscript describes studies that contribute to our understanding of the ecological risks associated with chronic contaminant exposures to wildlife populations. Here, we assessed ecologically-important genes for important classes of environmental pollutants and population genetics of an estuarine fish species resident to estuaries along the Atlantic U.S. coast. Results of these studies are used to characterize the adaptive nature, mechanisms, benefits, and costs of compensatory responses as demonstrated by multiple independently evolving populations. General impacts from this contribution include improved understanding by managers and scientists of links between human activities, natural dynamics, ecological stressors and ecosystem condition.
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Record Details:Record Type: DOCUMENT (JOURNAL/PEER REVIEWED JOURNAL)
Organization:U.S. ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF RESEARCH AND DEVELOPMENT
NATIONAL HEALTH AND ENVIRONMENTAL EFFECTS RESEARCH LAB
ATLANTIC ECOLOGY DIVISION
POPULATION ECOLOGY BRANCH