The spatial patterns of non-neutral genetic variations at fine spatial scales and their possible associations with microenvironments have not been well-documented for tree populations. Based on 25–32 SNP markers, we examine whether non-neutral SNPs and their associations with microenvironments can be detected in FcMYB1603 , a gene homologous to that encoding a protein induced by drought stress in Arabidopsis thaliana for the 166 adult trees in a 1-ha plot in a mature population of Fagus crenata . In the 83 individuals of a younger cohort of below canopy trees, the nonsynonymous SNP at locus FcMYB1603_684 exhibited a spatial signature representing a departure from the expected spatial patterns of neutral genetic variation. Evaluations of non-neutrality for this locus were robust against the potential risks of false positives due to the low number of SNP loci, a low criterion set for minor allele frequency, and any edge effect on the trees’ spatial structure. An older cohort exhibited no signal of the existence of non-neutral genetic variation, suggesting that temporal fluctuation in the microenvironmental conditions on the forest floor may have exposed different cohorts to different magnitudes of selection pressure. Although genotypes of the locus showed a spatial association with a microenvironmental variable potentially related to soil moisture, the present study was subject to a limitation due to the generally low polymorphism of nonsynonymous loci within the single plot, which suggests that it will be important to replicate the study design in order to carry out research on fine-scale non-neutral genetic variations.

中文翻译：

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古老山毛榉林中 SNP 精细尺度空间模式的评估

在精细空间尺度上的非中性遗传变异的空间模式及其与微环境的可能关联尚未针对树木种群进行充分记录。基于 25-32 个 SNP 标记，我们检查是否可以在 FcMYB1603 中检测到非中性 SNP 及其与微环境的关联，FcMYB1603 与编码拟南芥干旱胁迫诱导的蛋白质的基因同源，用于 1- ha 小区在成熟的 Fagus crenata 种群中。在冠层树下较年轻队列的 83 个个体中，基因座 FcMYB1603_684 处的非同义 SNP 表现出空间特征，代表偏离中性遗传变异的预期空间模式。由于 SNP 基因座数量少、次要等位基因频率标准设置低以及对树木空间结构的任何边缘影响，因此对该基因座的非中性性评估对于假阳性的潜在风险是稳健的。一个较老的队列没有表现出存在非中性遗传变异的信号，这表明森林地面微环境条件的时间波动可能使不同的队列暴露于不同程度的选择压力。尽管该位点的基因型显示出与可能与土壤水分相关的微环境变量的空间关联，但由于单个地块内非同义位点的多态性普遍较低，本研究受到限制，