Arenas Sebastián, Cruz-Nicolás Jorge, Giles-Pérez Gustavo, Barrera-Redondo Josué, Reyes-Galindo Verónica, Mastretta-Yanes Alicia, Aguirre-Planter Erika, Eguiarte Luis E, Jaramillo-Correa Juan Pablo
Departamento de Ecología Evolutiva, Instituto de Ecología Universidad Nacional Autónoma de México Ciudad de México México.
Department of Plant Protection Biology Swedish University of Agricultural Sciences Alnarp Sweden.
Evol Appl. 2025 Jul 9;18(7):e70116. doi: 10.1111/eva.70116. eCollection 2025 Jul.
Local adaptation is a fundamental process that allows populations to thrive in their native environment, often increasing genetic differentiation with neighboring stands. However, detecting the molecular basis and selective factors responsible for local adaptation remains a challenge, particularly in sessile, non-model species with long life cycles, such as forest trees. Local adaptation in trees is not only modeled by climatic factors, but also by soil variation. Such variation depends on dynamic geological and ecological processes that generate a highly heterogeneous selective mosaic that may differentially condition tree adaptation both at the range-wide and local scales. This could be particularly manifest in species inhabiting mountain ranges that were formed by diverse geological events, like sacred fir (), a conifer endemic to the mountains of central Mexico. Here, we used landscape genomics approaches to investigate how chemical edaphic variation influences the genetic structure of this species at the range-wide and local scales. After controlling for neutral genetic structure, we performed genotype-environment associations and identified 49 and 23 candidate SNPs at the range-wide and local scales, respectively, with little overlap between scales. We then developed polygenic models with such candidates, which accounted for ~20% of the range-wide variation in soil concentration, electric conductivity (), and , and for the local variation in soil and organic carbon content (). Spatial Principal Component Analyses further highlighted the role of geography and population isolation in explaining this genetic-soil co-variation. Our findings reveal that local adaptation in trees is the result of an intricate interaction between soil chemical properties and the local population's genetic makeup, and that the selective factors driving such adaptation greatly vary and are not necessarily predictable across spatial scales. These results highlight the need to consider edaphic variation in forest genetic studies (including common garden experiments) and in conservation, management and assisted migration programs.
局部适应是一个基本过程，它使种群能够在其原生环境中繁荣发展，通常会增加与相邻林分的遗传分化。然而，检测导致局部适应的分子基础和选择因素仍然是一项挑战，特别是在具有长生命周期的固着性非模式物种中，例如林木。树木的局部适应不仅由气候因素塑造，也受到土壤变异的影响。这种变异取决于动态的地质和生态过程，这些过程产生了高度异质的选择镶嵌体，可能在广泛和局部尺度上对树木适应产生不同的影响。这在栖息于由不同地质事件形成的山脉中的物种中可能尤为明显，比如墨西哥中部山区特有的针叶树神圣冷杉。在这里，我们使用景观基因组学方法来研究土壤化学变异如何在广泛和局部尺度上影响该物种的遗传结构。在控制中性遗传结构后，我们进行了基因型 - 环境关联分析，并分别在广泛和局部尺度上鉴定出49个和23个候选单核苷酸多态性（SNP），不同尺度间几乎没有重叠。然后，我们用这些候选基因开发了多基因模型，这些模型分别解释了土壤磷浓度、电导率以及土壤磷和有机碳含量局部变异中约20%的广泛变异。空间主成分分析进一步突出了地理和种群隔离在解释这种遗传 - 土壤共变中的作用。我们的研究结果表明，树木的局部适应是土壤化学性质与当地种群遗传组成之间复杂相互作用的结果，并且驱动这种适应的选择因素差异很大，在不同空间尺度上不一定可预测。这些结果强调了在森林遗传研究（包括共同园实验）以及保护、管理和辅助迁移计划中考虑土壤变异的必要性。
