Environmental contaminants pose a significant selection pressure across taxa, potentiating evolved resistance to chemicals. However, rapid evolution may alter molecular and physiological homeostasis leading to trade-offs. To elucidate molecular underpinnings of evolved chemical resistance, we compared liver gene expression and methylation profiles in polycyclic aromatic hydrocarbon (PAH)-adapted Atlantic killifish (Fundulus heteroclitus) in the Republic site (RP), Elizabeth River, Virginia with PAH-sensitive Kings Creek (KC) fish. We found 1607 differentially expressed and 2252 alternatively spliced genes between RP and KC, with highly enriched genes involving lipid and amino acid metabolism, respectively. While 308 genes had differentially methylated regions, only 13 of these genes were differentially expressed. The aryl hydrocarbon receptor 2b gene (ahr2b) was differentially methylated and expressed, as well as alternatively spliced signifying its critical role in mediating PAH tolerance. Notably, the intrapopulation coefficient of variation (CoV) was lower in 82% of 17,566 expressed genes in RP fish compared to KC fish. Among other pathways, these genes with low CoV were highly enriched in bioenergetic processes inferring reduced metabolic physiological variation as a population in RP fish. Altered metabolic gene expression and overall reduced gene expression variance in RP fish warrant further studies on fitness trade-offs including altered susceptibility to other stressors associated with rapid adaptation to anthropogenic pressures.

中文翻译：

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转录组学和甲基组学分析显示，PAH 适应的大西洋基利鱼的生物合成过程发生了显着变化，种群内基因表达方差减少


环境污染物对整个分类群构成了巨大的选择压力，增强了对化学品的进化耐药性。然而，快速进化可能会改变分子和生理稳态，从而导致权衡。为了阐明进化化学耐药性的分子基础，我们比较了弗吉尼亚州伊丽莎白河共和遗址 （RP） 中多环芳烃 （PAH） 适应的大西洋基利鱼 （Fundulus heteroclitus） 的肝脏基因表达和甲基化谱与 PAH 敏感的国王溪 （KC） 鱼。我们在 RP 和 KC 之间发现了 1607 个差异表达基因和 2252 个选择性剪接基因，其中高度富集的基因分别涉及脂质和氨基酸代谢。虽然 308 个基因具有差异甲基化区域，但其中只有 13 个基因是差异表达的。芳烃受体 2b 基因 （ahr2b） 被差异甲基化和表达，以及选择性剪接，表明它在介导 PAH 耐受性中的关键作用。值得注意的是，与 KC 鱼相比，RP 鱼中 82 个表达基因中有 17,566% 的种群内变异系数 （CoV） 较低。在其他途径中，这些低 CoV 基因在生物能量过程中高度富集，推断 RP 鱼种群的代谢生理变异减少。RP 鱼代谢基因表达的改变和基因表达变异的总体降低需要进一步研究适应性权衡，包括对与快速适应人为压力相关的其他压力源的易感性改变。