Microevolutionary processes in a foundation tree inform macrosystem patterns of community biodiversity and structure

Despite an increased focus on multiscale relationships and interdisciplinary integration, few macroecological studies consider the contribution of genetic-based processes to landscape-scale patterns. We tested the hypothesis that tree genetics, climate, and geography jointly drive continental-scale patterns of community structure, using genome-wide SNP data from a broadly distributed foundation tree species (Populus fremontii S. Watson) and two dependent communities (leaf-modifying arthropods and fungal endophytes) spanning southwestern North America. Four key findings emerged: (1) Tree genetic structure was a significant predictor for both communities; however, the strength of influence was both scale- and community-dependent. (2) Tree genetics was the primary driver for endophytes, explaining 17% of variation in continental-scale community structure, whereas (3) climate was the strongest predictor of arthropod structure (24%). (4) Power to detect tree genotype—community phenotype associations changed with scale of genetic organization, increasing from individuals to populations to ecotypes, emphasizing the need to consider nonstationarity (i.e., changes in the effects of factors on ecological processes across scales) when inferring macrosystem properties. Our findings highlight the role of foundation tree species as drivers of macroscale community structure and provide macrosystems ecology with a theoretical framework for linking fine- and intermediate-scale genetic processes to landscape-scale patterns. Management of genetic diversity harbored within foundation species is a critical consideration for conserving and sustaining regional biodiversity.

尽管当前学界对多尺度关联与跨学科整合的关注度日益提升，但鲜有宏观生态学研究考量遗传过程对景观尺度格局的贡献。本研究依托广泛分布的建群树种（弗雷蒙特杨，*Populus fremontii* S. Watson）以及横跨北美西南部的两类依存群落（食叶节肢动物与真菌内生菌）的全基因组单核苷酸多态性（Single Nucleotide Polymorphism, SNP）数据，验证了树木遗传、气候与地理因素共同驱动大陆尺度群落结构格局的假说。本研究得到四项核心结论：(1) 树木遗传结构对两类群落均具有显著的预测效力，但影响强度同时受尺度与群落类型的调控；(2) 对于真菌内生菌群落而言，树木遗传是其主导驱动因素，可解释大陆尺度群落结构17%的变异；(3) 气候因素则是节肢动物群落结构的最强预测因子，解释度达24%；(4) 检测树木基因型与群落表型关联的效力随遗传组织尺度发生变化，从个体到种群再到生态型逐步提升，这强调了在推断宏系统属性时，需考虑非平稳性（即跨尺度下生态过程的影响因子效应会发生变化）。本研究结果凸显了建群树种作为宏观尺度群落结构驱动因子的作用，并为宏系统生态学搭建了将精细与中等尺度遗传过程与景观尺度格局相联结的理论框架。保护与维持区域生物多样性的关键举措之一，需纳入建群树种所携带的遗传多样性管理环节。