School of Biological Sciences, University of Bristol, UK.
School of Biological Sciences, Monash University, Melbourne, Australia.
Evolution. 2022 Jun;76(6):1229-1245. doi: 10.1111/evo.14478. Epub 2022 Apr 18.
The evolution of plastic responses to external cues allows species to maintain fitness in response to the environmental variations they regularly experience. However, it remains unclear how plasticity evolves during adaptation. To test whether distinct patterns of plasticity are associated with adaptive divergence, we quantified plasticity for two closely related but ecologically divergent Sicilian daisy species (Senecio, Asteraceae). We sampled 40 representative genotypes of each species from their native range on Mt. Etna and then reciprocally transplanted multiple clones of each genotype into four field sites along an elevational gradient that included the native elevational range of each species, and two intermediate elevations. At each elevation, we quantified survival and measured leaf traits that included investment (specific leaf area), morphology, chlorophyll fluorescence, pigment content, and gene expression. Traits and differentially expressed genes that changed with elevation in one species often showed little changes in the other species, or changed in the opposite direction. As evidence of adaptive divergence, both species performed better at their native site and better than the species from the other habitat. Adaptive divergence is, therefore, associated with the evolution of distinct plastic responses to environmental variation, despite these two species sharing a recent common ancestor.
对外界线索的可塑性反应的进化使物种能够在经常经历的环境变化中保持适应能力。然而，可塑性在适应过程中是如何进化的仍然不清楚。为了测试不同的可塑性模式是否与适应性分化有关，我们量化了两种密切相关但生态上有差异的西西里雏菊物种（千里光，菊科）的可塑性。我们从埃特纳山的原生境中采集了每个物种的 40 个代表性基因型，然后将每个基因型的多个克隆相互移植到四个沿海拔梯度的野外地点，其中包括每个物种的原生海拔范围和两个中间海拔。在每个海拔高度，我们量化了存活率，并测量了包括投资（比叶面积）、形态、叶绿素荧光、色素含量和基因表达在内的叶片特征。在一个物种中随海拔变化的特征和差异表达基因往往在另一个物种中变化很小，或者变化方向相反。作为适应性分化的证据，两个物种在其原生地的表现都比其他栖息地的物种好。因此，尽管这两个物种有一个最近的共同祖先，但适应性分化与对环境变化的不同可塑性反应的进化有关。
