Data from: Rapid evolution caused by pollinator loss in Mimulus guttatus

Anthropogenic perturbations including habitat loss and emerging disease are changing pollinator communities and generating novel selection pressures on plant populations. Disruption of plant-pollinator relationships is predicted to cause plant mating system evolution, although this process has not been directly observed. This study demonstrates the immediate evolutionary effects of pollinator loss within experimental populations of a predominately outcrossing wildflower. Initially equivalent populations evolved for five generations within two pollination treatments: abundant bumblebee pollinators vs. no pollinators. The populations without pollinators suffered greatly reduced fitness in early generations but rebounded as they evolved an improved ability to self-fertilize. All populations diverged in floral, developmental, and life history traits, but only a subset of characters showed clear association with pollination treatment. Pronounced treatment effects were noted for anther-stigma separation and autogamous seed set. Dramatic allele frequency changes at two chromosomal polymorphisms occurred in the no pollinator populations, explaining a large fraction of divergence in pollen viability. The pattern of phenotypic and genetic changes in this experiment favors a sequential model for the evolution of the multi-trait ‘selfing syndrome’ observed throughout angiosperms.

人为扰动（anthropogenic perturbations）包括栖息地丧失和新兴疾病，正在改变传粉者（pollinator）群落，并对植物种群产生新的选择压力。植物-传粉者互作关系的瓦解被预测会引发植物交配系统的演化，但这一过程尚未被直接观测到。本研究以主要异交的野生开花植物实验种群为对象，阐明了传粉者丧失引发的即时演化效应。初始状态一致的种群在两种传粉处理下历经五代演化：充足熊蜂（bumblebee）传粉组与无传粉组。无传粉组种群在早期世代的适合度（fitness）大幅下降，但随着演化出更优的自交受精能力，其适合度得以回升。所有种群在花部性状、发育特征与生活史性状上均出现分化，但仅有部分性状与传粉处理存在显著关联。雌雄蕊间距（anther-stigma separation）与自交结实率（autogamous seed set）呈现出显著的处理效应。无传粉组种群在两处染色体多态性（chromosomal polymorphisms）位点上发生了显著的等位基因频率（allele frequency）变化，该变化可解释花粉活力（pollen viability）差异的大部分成因。本实验中表型与遗传变化的模式，支持了被子植物（angiosperms）中广泛存在的多性状‘自交综合征（selfing syndrome）’的序贯演化模型。