Kelp are foundation species threatened by ongoing warming trends and increased harvesting pressure. This emphasizes the need to study genetic structure over various spatial scales to resolve demographic and genetic processes underpinning resilience. Here, we investigate the genetic diversity in the kelp, Laminaria digitata, in previously understudied southern (trailing-edge) and northern (range-centre) regions in the Northeastern Atlantic Ocean. There was strong hierarchical spatial structuring with significantly lower genetic variability and gene flow among southern populations. As these span the area of the Hurd’s deep Pleistocene glacial refuge, the current low variation likely reflects a fraction of previous levels that has been eroded at the species southern edge. Northern variability and private alleles also indicate contributions from cryptic northern glacial refugia. Contrary to expectations of a positive relationship between neutral genetic diversity and resilience, a previous study reported individuals from the same genetically impoverished southern populations to be better adapted to cope with thermal stress than northern individuals. This not only demonstrates that neutral genetic diversity may be a poor indicator of resilience to environmental stress but also confirms that extirpation of southern populations will result in the loss of evolved, not just potential, adaptations for resilience.

中文翻译：

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在凉爽的北方海带分层遗传结构，掌状海带：为保护和管理的影响

海带是受持续升温趋势和收获压力增加威胁的基础物种。这强调需要研究各种空间尺度上的遗传结构，以解决支撑弹性的人口和遗传过程。在这里，我们调查海带，海带指的遗传多样性，以前曾研究过东北大西洋的南部（后缘）和北部（范围中心）地区。在南方人群中，存在强大的分级空间结构，遗传变异性和基因流明显较低。当它们跨越赫德深部的更新世冰川避难所的区域时，当前的低变化可能反映了先前水平的一小部分已经在物种南部边缘被侵蚀了。北部的变异性和私人等位基因也表明来自神秘的北部冰川避难所。与对中性遗传多样性和适应力之间呈正相关关系的期望相反，一项先前的研究报告说，与北方个体相比，来自相同遗传贫困的南方人群的个体更能适应热应激。