Data from: Geographic structure and adaptive population differentiation in herbivore defense genes in European aspen (Populus tremula L., Salicaceae)

When a phenotypic trait is subjected to spatially variable selection and local adaptation, the underlying genes controlling the trait are also expected to show strong patterns of genetic differentiation because alternative alleles are favoured in different geographical locations. Here, we study 71 single nucleotide polymorphisms (SNPs) from seven genes associated with inducible defence responses in a sample of Populus tremula collected from across Sweden. Four of these genes (PPO2, TI2, TI4 and TI5) show substantial population differentiation, and a principal component analyses conducted on the defence SNPs divides the Swedish population into three distinct clusters. Several defence SNPs show latitudinal clines, although these were not robust to multiple testing. However, five SNPs (located within TI4 and TI5) show strong longitudinal clines that remain significant after multiple test correction. Genetic geographical variation, supporting local adaptation, has earlier been confirmed in genes involved in the photoperiod pathway in P. tremula, but this is, to our knowledge, one of the first times that geographical variation has been found in genes involved in plant defence against antagonists.当某一表型性状受到空间可变选择与局部适应作用时，调控该性状的核心基因也会呈现显著的遗传分化模式——这是因为不同地理区域会青睐不同的等位基因。本研究以瑞典全境采集的欧洲山杨（Populus tremula）样本为材料，分析了7个与诱导型防御反应相关的基因上的71个单核苷酸多态性（single nucleotide polymorphisms, SNPs）。其中4个基因（PPO2、TI2、TI4和TI5）呈现出显著的种群分化；基于防御相关SNPs开展的主成分分析将瑞典山杨种群划分为三个截然不同的聚类簇。部分防御相关SNPs呈现出纬度梯度分布模式，但这类关联在多重检验校正后并不显著。不过，位于TI4和TI5基因内的5个SNPs则呈现出显著的经度梯度分布模式，且该模式在经过多重检验校正后依然保持统计学显著性。此前已有研究证实欧洲山杨光周期通路相关基因存在支持局部适应的地理遗传变异，但据我们所知，本研究是首次在植物拮抗物防御相关基因中发现此类地理变异的研究之一。