Molecular Ecology Lab, Flinders University, Bedford Park, SA 5042, Australia.
Konrad Lorenz Institute of Ethology, University of Veterinary Medicine, 1160 Vienna, Austria.
Proc Natl Acad Sci U S A. 2020 Jul 21;117(29):17112-17121. doi: 10.1073/pnas.1921124117. Epub 2020 Jul 9.
Resilience to environmental stressors due to climate warming is influenced by local adaptations, including plastic responses. The recent literature has focused on genomic signatures of climatic adaptation, but little is known about how plastic capacity may be influenced by biogeographic and evolutionary processes. We investigate phenotypic plasticity as a target of climatic selection, hypothesizing that lineages that evolved in warmer climates will exhibit greater plastic adaptive resilience to upper thermal stress. This was experimentally tested by comparing transcriptomic responses within and among temperate, subtropical, and desert ecotypes of Australian rainbowfish subjected to contemporary and projected summer temperatures. Critical thermal maxima were estimated, and ecological niches delineated using bioclimatic modeling. A comparative phylogenetic expression variance and evolution model was used to assess plastic and evolved changes in gene expression. Although 82% of all expressed genes were found in the three ecotypes, they shared expression patterns in only 5 out of 236 genes that responded to the climate change experiment. A total of 532 genes showed signals of adaptive (i.e., genetic-based) plasticity due to ecotype-specific directional selection, and 23 of those responded to projected summer temperatures. Network analyses demonstrated centrality of these genes in thermal response pathways. The greatest adaptive resilience to upper thermal stress was shown by the subtropical ecotype, followed by the desert and temperate ecotypes. Our findings indicate that vulnerability to climate change will be highly influenced by biogeographic factors, emphasizing the value of integrative assessments of climatic adaptive traits for accurate estimation of population and ecosystem responses.
由于气候变暖，对环境胁迫的适应能力受到了局部适应的影响，包括可塑性反应。最近的文献主要集中在气候适应的基因组特征上，但对于可塑性能力如何受到生物地理和进化过程的影响知之甚少。我们将表型可塑性作为气候选择的目标进行研究，假设在温暖气候中进化的谱系将表现出对较高热应激更大的可塑性适应恢复力。这通过比较澳大利亚彩虹鱼的温带、亚热带和沙漠生态型在当代和预测的夏季温度下的转录组反应来进行实验测试。通过生物气候建模估计了临界热最大值，并划定了生态位。比较系统发育表达方差和进化模型用于评估基因表达的可塑性和进化变化。尽管所有表达的基因中有 82%存在于三个生态型中，但它们在响应气候变化实验的 236 个基因中仅有 5 个具有相同的表达模式。共有 532 个基因表现出由于生态型特异性定向选择而导致的适应性（即遗传基础）可塑性的信号，其中 23 个基因对预测的夏季温度有反应。网络分析表明，这些基因在热响应途径中处于中心地位。对较高热应激的适应恢复力最大的是亚热带生态型，其次是沙漠和温带生态型。我们的研究结果表明，对气候变化的脆弱性将受到生物地理因素的高度影响，这强调了对气候适应特征进行综合评估对于准确估计种群和生态系统反应的价值。
