Institute of Integrative Biology, ETH Zurich, Zurich, Switzerland.
Department of Terrestrial Ecology, NIOO-KNAW, Wageningen, The Netherlands.
Glob Chang Biol. 2018 Feb;24(2):e534-e544. doi: 10.1111/gcb.13947. Epub 2017 Nov 15.
Although climate warming is expected to make habitat beyond species' current cold range edge suitable for future colonization, this new habitat may present an array of biotic or abiotic conditions not experienced within the current range. Species' ability to shift their range with climate change may therefore depend on how populations evolve in response to such novel environmental conditions. However, due to the recent nature of thus far observed range expansions, the role of rapid adaptation during climate change migration is only beginning to be understood. Here, we evaluated evolution during the recent native range expansion of the annual plant Dittrichia graveolens, which is spreading northward in Europe from the Mediterranean region. We examined genetically based differentiation between core and edge populations in their phenology, a trait that is likely under selection with shorter growing seasons and greater seasonality at northern latitudes. In parallel common garden experiments at range edges in Switzerland and the Netherlands, we grew plants from Dutch, Swiss, and central and southern French populations. Population genetic analysis following RAD-sequencing of these populations supported the hypothesized central France origins of the Swiss and Dutch range edge populations. We found that in both common gardens, northern plants flowered up to 4 weeks earlier than southern plants. This differentiation in phenology extended from the core of the range to the Netherlands, a region only reached from central France over approximately the last 50 years. Fitness decreased as plants flowered later, supporting the hypothesized benefits of earlier flowering at the range edge. Our results suggest that native range expanding populations can rapidly adapt to novel environmental conditions in the expanded range, potentially promoting their ability to spread.
尽管预计气候变暖将使物种目前冷范围边缘以外的栖息地适合未来的殖民化，但这种新的栖息地可能会带来一系列生物或非生物条件，而这些条件在当前范围内是没有经历过的。物种随着气候变化而改变其范围的能力可能取决于它们在多大程度上能够通过进化来应对这些新的环境条件。然而，由于迄今为止观察到的范围扩张是最近才出现的，因此快速适应气候变化移民过程中的作用才刚刚开始被理解。在这里，我们评估了一年生植物 Dittrichia graveolens 在其最近的原生范围扩张过程中的进化情况，该植物正在从地中海地区向北扩展到欧洲。我们研究了核心种群和边缘种群在物候方面的遗传差异，这是一个可能受到选择的特征，因为在较短的生长季节和更高的季节性条件下，物候变化可能会受到选择。在瑞士和荷兰的范围边缘进行平行的常见花园实验中，我们从荷兰、瑞士和法国中部和南部的种群中种植植物。对这些种群进行 RAD 测序的种群遗传分析支持了瑞士和荷兰范围边缘种群起源于法国中部的假设。我们发现，在两个常见的花园中，北方的植物比南方的植物早开花多达 4 周。这种物候差异从范围的核心延伸到了荷兰，这一地区在过去大约 50 年才从法国中部到达。随着植物开花时间的延迟，适应性降低，这支持了在范围边缘更早开花的假设好处。我们的研究结果表明，原生范围扩张的种群可以快速适应扩张范围中的新环境条件，从而提高其扩散能力。
