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The Genetic Basis for Evolved Tolerance to Dioxin-Like Compounds in Wild Atlantic Killifish: More Than the Aryl Hydrocarbon Receptor
Citation:
Nacci, D., E. Waits, D. Proestou, D. Champlin, J. Martinson, B. Rinner, AND S. Morris. The Genetic Basis for Evolved Tolerance to Dioxin-Like Compounds in Wild Atlantic Killifish: More Than the Aryl Hydrocarbon Receptor. Society of Environmental Toxicology and Chemistry (SETAC) North America 35th Annual Meeting, Vancouver, BC, CANADA, November 09 - 13, 2014.
Impact/Purpose:
This presentation describes research that contributes 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.
Description:
Populations of Atlantic killifish (Fundulus heteroclitus) resident to some US urban estuaries have independently evolved extreme and inherited tolerance to toxic dioxin-like compounds (DLCs). To further understand the genetic basis for this trait, we densely genotyped families of F2 recombinant embryos derived from tolerant killifish resident to the New Bedford (NB) PCB Superfund site (MA, USA). Quantitative Trait Locus (QTL) analysis identified main, interacting and epistatic genetic markers of NB tolerance that together provide an unusually comprehensive accounting of this complex trait: ≥ 68% phenotypic variance explained, LOD (Logarithm of Odds ) 23.68; p = 8.33e-15. An integrated genetic linkage map for the species was constructed to characterize physical relationships among QTLs across the killifish genome. This map and recently identified killifish gene models (Fundulus genome consortium) provided invaluable tools to explore syntenic and orthologous comparisons across fish and other species, and infer potential causal relationships among loci identified through QTL associations. Consistent with mechanistic knowledge of DLC toxicity in fish and other vertebrates, the aryl hydrocarbon receptor (AHR2) accounts for 16.77% of phenotypic variation; however, QTLs on an independent linkage group have even greater explanatory power (43.74%). The species-wide relevance of some of these NB QTLs was suggested through genetic screening of three other DLC-tolerant populations, resident to highly contaminated urban estuaries. These results advance our understanding of intra- and inter-specific variation in DLC toxicity, and permit insight into rapid evolutionary mechanisms.