Department of Ecology and Evolutionary Biology, University of Kansas, 1200 Sunnyside Avenue, Lawrence, Kansas 66046, USA.
Evolution. 2011 Sep;65(9):2541-52. doi: 10.1111/j.1558-5646.2011.01326.x.
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 versus 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 multitrait "selfing syndrome" observed throughout angiosperms.
人为干扰，包括生境丧失和新出现的疾病，正在改变传粉者群落，并对植物种群产生新的选择压力。尽管尚未直接观察到，但预计植物-传粉者关系的破坏将导致植物交配系统的进化。本研究在一个主要异交的野生花卉的实验种群中证明了传粉者丧失的直接进化效应。最初，在两个授粉处理下，具有相同初始条件的种群进化了五代：丰富的熊蜂传粉者与无传粉者。没有传粉者的种群在前几代中遭受了严重的适应性降低，但随着它们进化出提高自交能力而反弹。所有种群在花部、发育和生活史特征上都发生了分歧，但只有一部分特征与授粉处理有明显的关联。在花药-柱头分离和自交种子结实方面观察到明显的处理效应。在无传粉者种群中，两个染色体多态性发生了显著的等位基因频率变化，解释了花粉活力差异的很大一部分。这个实验中的表型和遗传变化模式有利于多性状“自交综合征”进化的顺序模型，该模型在整个被子植物中都有观察到。
