Suzuki Yuichiro, Amaya Stephanie, Gonzalez Paula, Becerril Daniela, Aquit Surisadai, Davis Maya, Hoesel Madeline, Chou Elizabeth, Khong Hesper, Zaia Kathryn, Park Heidi S, Nijhout H Frederik, Tjaden Brian
Department of Biological Sciences, Wellesley College, Wellesley, MA 02481.
Department of Infectious Diseases, Massachusetts General Hospital, Boston, MA 02114.
Proc Natl Acad Sci U S A. 2025 Mar 25;122(12):e2425004122. doi: 10.1073/pnas.2425004122. Epub 2025 Mar 19.
How organisms evolve under extreme environmental changes is a critical question in the face of global climate change. Genetic accommodation is an evolutionary process by which natural selection acts on novel phenotypes generated through repeated encounters with extreme environments. In this study, polyphenic and monophenic strains of the mutant tobacco hornworm, , were evolved via genetic accommodation of heat stress-induced phenotypes, and the molecular differences between the two strains were explored. Transcriptomic analyses showed that epigenetic and hormonal differences underlie the differences between the two strains and their distinct responses to temperature. DNA methylation had diverged between the two strains potentially mediating genetic assimilation. Juvenile hormone (JH) signaling in the polyphenic strain was temperature sensitive, whereas in the monophenic strain, JH signaling remained low at all temperatures. Although 20-hydroxyecdysone titers were elevated under heat shock conditions in both strains, the strains did not differ in the titers. Tyrosine hydroxylase was also found to differ between the two strains at different temperatures, and its expression could be modulated by topical application of a JH analog. Finally, heat shock of unselected mutants demonstrated that the expression of the JH-response gene, (), increased within the first 30 min of heat shock, suggesting that JH levels respond readily to thermal stress. Our study highlights the critical role that hormones and epigenetics play during genetic accommodation and potentially in the evolution of populations in the face of climate change.
在全球气候变化的背景下，生物体如何在极端环境变化中进化是一个关键问题。遗传顺应是一个进化过程，通过这个过程，自然选择作用于因反复遭遇极端环境而产生的新表型。在本研究中，通过对热应激诱导表型的遗传顺应，使突变型烟草天蛾的多型和单型品系得以进化，并探究了这两个品系之间的分子差异。转录组分析表明，表观遗传和激素差异是这两个品系之间差异及其对温度的不同反应的基础。两个品系之间的DNA甲基化已经发生分歧，这可能介导了遗传同化。多型品系中的保幼激素（JH）信号对温度敏感，而在单型品系中，JH信号在所有温度下都保持在低水平。虽然在热休克条件下两个品系中的20-羟基蜕皮酮滴度都升高了，但两个品系在滴度上没有差异。还发现酪氨酸羟化酶在两个品系的不同温度下存在差异，并且其表达可以通过局部应用JH类似物来调节。最后，对未选择的突变体进行热休克表明，JH反应基因（）的表达在热休克的前30分钟内增加，这表明JH水平对热应激反应迅速。我们的研究强调了激素和表观遗传学在遗传顺应过程中以及面对气候变化时种群进化中可能发挥的关键作用。
