show Abstracthide AbstractEmbryos from 8 populations of killifish, four with evolved tolerances, were exposed to PCB-126. Approximately 5 replicate embryos per treatment/control were sequenced. Desensitization of aryl hydrocarbon receptor signaling to PCB-126 is found in all four populations with evolved pollution tolerance, and represents the strongest transcriptional difference between tolerant and sensitive populations. Overall design: 4 populations with evolved tolerance (Bridgeport, Elizabeth River, New Bedford Harbor, and Newark) paired with a nearby sensitive population. One PCB-126 dose and 1 DMSO control, 5 replicates per treatment. Embryos were exposed from 1 day post fertilization to 10 days post fertilization (developmental stage 35).