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，是检验自然选择能否对抗基因流等对立演化力量的关键实验手段。鉴于可在真实基因型（而非种群）层面开展实验重复，且可利用分子标记评估野外的基因型-环境关联——这两点在多数有性物种中均无法实现——无性物种的此类研究可得到极大的促进。
本研究以无性生殖的西洋蒲公英（Taraxacum officinale）为研究对象，将6个目标基因型分别置于干旱、修剪及良性（对照）三种实验环境中，随后利用微卫星（microsatellites）标记评估野外的基因型-环境关联，以此检验G×E效应。
研究发现了显著的G×E效应：在良性环境中表现不佳的基因型，在胁迫环境（干旱或修剪）中表现最优。本研究选取的6个目标基因型，占当地种群植株总量的80%以上。
野外最常见的基因型在修剪环境（本研究区域的最普遍生境）中相对表现最佳，且该基因型的野外个体几乎全部生长在修剪草坪中。在良性实验环境中表现最优的基因型，在野外未修剪生境中的出现频率最高。
上述结果强烈表明存在极精细尺度的本地适应：仅数平方米的未修剪微生境，通常嵌入在更大面积的修剪草坪之中。
本研究通过选取无性生殖物种，得以将具有明确生态特征的基因型与高精度空间尺度的环境进行精准匹配。