Data from: Detecting small-scale genotype-environment interactions in apomictic dandelion (Taraxacum officinale) populations

Studies of genotype × environment interactions (G×E) and local adaptation provide critical tests of natural selection’s ability to counter opposing forces such as gene flow. Such studies may be greatly facilitated in asexual species, given the possibility for experimental replication at the level of true genotypes (rather than populations) and the possibility of using molecular markers to assess genotype-environment associations in the field (neither of which is possible for most sexual species). Here we tested for G×E in asexual dandelions (Taraxacum officinale) by subjecting six genotypes to experimental drought, mown, and benign (control) conditions, and subsequently using microsatellites to assess genotype-environment associations in the field. We found strong G×E, with genotypes that performed poorly under benign conditions showing the highest performance under stressful conditions (drought or mown). Our six focal genotypes comprise >80% of plants in local populations. The most common genotype in the field showed its highest relative performance under mown conditions (the most common habitat in our study area), and almost all plants of this genotype in the field were found growing in mowed lawns. Genotypes performing best under benign experimental conditions were found most frequently in unmown conditions in the field. These results are strongly indicative of local adaptation at a very small scale, with unmown microsites of only a few square meters typically embedded within larger mown lawns. By studying an asexual species we were able to map genotypes with known ecological characteristics to environments with high spatial precision.

基因型-环境互作（genotype × environment interactions, G×E）与本地适应的相关研究，是检验自然选择抗衡基因流等对立演化动力的关键实验依据。这类研究在无性生殖物种中得以高效开展，因为我们能够以真实基因型（而非种群）为单位开展实验重复，也可借助分子标记评估野外环境中的基因型-环境关联——这两点在多数有性生殖物种中均无法实现。本研究以无性生殖的西洋蒲公英（Taraxacum officinale）为对象，通过将6个目标基因型分别置于干旱、刈割与良性（对照）三种实验环境中，并借助微卫星（microsatellites）标记评估野外的基因型-环境关联，以此检验该物种的G×E效应。研究结果显示存在显著的G×E效应：在良性对照条件下生长表现较差的基因型，在胁迫环境（干旱或刈割）中的表现反而最优。本研究选取的6个目标基因型，占本地种群总植株数的80%以上。野外种群中最为常见的基因型，在刈割环境（本研究区域的最常见生境）中相对表现最优；且该基因型的野外植株几乎全部分布在修剪草坪中。在良性实验条件下表现最佳的基因型，在野外未受刈割的生境中分布最为广泛。上述结果强烈表明该物种存在极小尺度下的本地适应——仅数平方米的未修剪微生境，通常镶嵌于更大范围的修剪草坪之中。本研究通过聚焦无性生殖物种，得以将携带明确生态特征的基因型与空间精度极高的生境进行精准匹配。