Liesner Daniel, Fouqueau Louise, Valero Myriam, Roleda Michael Y, Pearson Gareth A, Bischof Kai, Valentin Klaus, Bartsch Inka
Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research Bremerhaven Germany.
UMI EBEA 3614, Evolutionary Biology and Ecology of Algae, CNRS Sorbonne Université, UC, UACH, Station Biologique de Roscoff Roscoff Cedex France.
Ecol Evol. 2020 Aug 17;10(17):9144-9177. doi: 10.1002/ece3.6569. eCollection 2020 Sep.
To understand the thermal plasticity of a coastal foundation species across its latitudinal distribution, we assess physiological responses to high temperature stress in the kelp in combination with population genetic characteristics and relate heat resilience to genetic features and phylogeography. We hypothesize that populations from Arctic and cold-temperate locations are less heat resilient than populations from warm distributional edges. Using meristems of natural populations from six locations ranging between Kongsfjorden, Spitsbergen (79°N), and Quiberon, France (47°N), we performed a common-garden heat stress experiment applying 15°C to 23°C over eight days. We assessed growth, photosynthetic quantum yield, carbon and nitrogen storage, and xanthophyll pigment contents as response traits. Population connectivity and genetic diversity were analyzed with microsatellite markers. Results from the heat stress experiment suggest that the upper temperature limit of is nearly identical across its distribution range, but subtle differences in growth and stress responses were revealed for three populations from the species' ecological range margins. Two populations at the species' warm distribution limit showed higher temperature tolerance compared to other populations in growth at 19°C and recovery from 21°C (Quiberon, France), and photosynthetic quantum yield and xanthophyll pigment responses at 23°C (Helgoland, Germany). In from the northernmost population (Spitsbergen, Norway), quantum yield indicated the highest heat sensitivity. Microsatellite genotyping revealed all sampled populations to be genetically distinct, with a strong hierarchical structure between southern and northern clades. Genetic diversity was lowest in the isolated population of the North Sea island of Helgoland and highest in Roscoff in the English Channel. All together, these results support the hypothesis of moderate local differentiation across European distribution, whereas effects are likely too weak to ameliorate the species' capacity to withstand ocean warming and marine heatwaves at the southern range edge.
为了解一种沿海基础物种在其纬度分布范围内的热可塑性，我们结合种群遗传特征评估了海带对高温胁迫的生理反应，并将热恢复力与遗传特征和系统地理学联系起来。我们假设来自北极和寒温带地区的种群比来自温暖分布边缘的种群热恢复力更低。我们使用了来自六个地点的自然种群的分生组织，这些地点位于斯瓦尔巴群岛的孔斯峡湾（北纬79°）和法国的基伯龙（北纬47°）之间，进行了一项共培养热胁迫实验，在八天内将温度从15°C升至23°C。我们评估了生长、光合量子产量、碳和氮储存以及叶黄素色素含量等反应性状。利用微卫星标记分析了种群连通性和遗传多样性。热胁迫实验结果表明，该物种在其分布范围内的高温上限几乎相同，但在该物种生态范围边缘的三个种群中，生长和胁迫反应存在细微差异。在该物种温暖分布极限的两个种群在19°C下生长以及从21°C恢复时（法国基伯龙），与其他种群相比表现出更高的温度耐受性，在23°C时（德国黑尔戈兰岛）光合量子产量和叶黄素色素反应也更高。来自最北端种群（挪威斯瓦尔巴群岛）的该物种，量子产量显示出最高的热敏感性。微卫星基因分型显示，所有采样种群在遗传上都是不同的，南北分支之间存在强烈的层次结构。遗传多样性在北海黑尔戈兰岛的孤立种群中最低，在英吉利海峡的罗斯科夫最高。总之，这些结果支持了在欧洲分布范围内存在适度局部分化的假设，然而这种影响可能太弱，无法改善该物种在南部范围边缘抵御海洋变暖和海洋热浪的能力。
