The genetics of killifish adaptation to pollution
NIEHS grantees have identified the complex genetics involved in the Atlantic killifish’s resilience to industrial contamination. The new findings are one step closer to better understanding which genes are linked with tolerance to specific chemicals and how genetic differences may affect an organism’s sensitivity to environmental contaminants.
Killifish living in four polluted East Coast estuaries have adapted to survive high levels of toxic industrial pollutants, including polychlorinated biphenyls, dioxins, and hydrocarbons. They can tolerate concentrations up to 8,000 times higher than similar killifish that are sensitive to the pollution. To better understand the genetic basis for this adaptation, the researchers sequenced the genomes of 384 individual killifish from four nonpolluted sites and compared those with killifish from polluted sites in New Bedford Harbor, Massachusetts; Newark Bay, New Jersey; Connecticut’s Bridgeport area; and Virginia’s Elizabeth River.
The genetic analysis identified hundreds of genome regions that appeared to have undergone natural selection in the pollution-resistant killifish. Several of the regions appeared in all four resistant populations and included genes involved in the previously identified aryl hydrocarbon receptor signaling pathway. These findings showed that there are likely a limited number of evolutionary paths for adaptation to pollution. Results from the new study also suggested that the genetic diversity of killifish made them unusually well-positioned to quickly adapt and survive high levels of pollution.
Citation: Reid NM, Proestou DA, Clark BW, Warren WC, Colbourne JK, Shaw JR, Karchner SI, Hahn ME, Nacci D, Oleksiak MF, Crawford DL, Whitehead A. 2016. The genomic landscape of rapid repeated evolutionary adaptation to toxic pollution in wild fish. Science 354(6317):1305–1308.