Rêgo Alexandre, Baur Julian, Girard-Tercieux Camille, de la Paz Celorio-Mancera Maria, Stelkens Rike, Berger David
Department of Ecology and Genetics, Uppsala University, Uppsala, Sweden.
Department of Zoology, Stockholm University, Stockholm, Sweden.
Nat Ecol Evol. 2025 May 16. doi: 10.1038/s41559-025-02716-5.
Climate warming is threatening biodiversity by increasing temperatures beyond the optima of many ectotherms. Owing to the inherent non-linear relationship between temperature and the rate of cellular processes, such shifts towards hot temperature are predicted to impose stronger selection compared with corresponding shifts towards cold temperature. This suggests that when adaptation to warming occurs, it should be relatively rapid and predictable. Here we tested this hypothesis from the level of single-nucleotide polymorphisms to life-history traits in the beetle Callosobruchus maculatus. We conducted an evolve-and-resequence experiment on three genetic backgrounds of the beetle reared at hot or cold temperature. Indeed, we find that phenotypic evolution was faster and more repeatable at hot temperature. However, at the genomic level, adaptation to heat was less repeatable when compared across genetic backgrounds. As a result, genomic predictions of phenotypic adaptation in populations exposed to hot temperature were accurate within, but not between, backgrounds. These results seem best explained by genetic redundancy and an increased importance of epistasis during adaptation to heat, and imply that the same mechanisms that exert strong selection and increase repeatability of phenotypic evolution at hot temperature reduce repeatability at the genomic level. Thus, predictions of adaptation in key phenotypes from genomic data may become increasingly difficult as climates warm.
气候变暖正通过将温度升高到许多变温动物的最适温度之上，威胁着生物多样性。由于温度与细胞过程速率之间存在固有的非线性关系，预计与向低温的相应转变相比，向高温的这种转变会施加更强的选择压力。这表明，当发生对变暖的适应时，应该相对迅速且可预测。在这里，我们从单核苷酸多态性水平到黄斑豆象的生活史特征对这一假设进行了检验。我们在高温或低温下饲养的该甲虫的三种遗传背景上进行了进化与重测序实验。确实，我们发现高温下的表型进化更快且更具重复性。然而，在基因组水平上，跨遗传背景比较时，对热的适应重复性较差。因此，暴露于高温下的种群中表型适应的基因组预测在同一背景内是准确的，但在不同背景之间则不准确。这些结果似乎最好用遗传冗余以及热适应过程上位性重要性增加来解释，这意味着在高温下施加强选择并增加表型进化重复性的相同机制，在基因组水平上降低了重复性。因此，随着气候变暖，从基因组数据预测关键表型的适应性可能会变得越来越困难。
