Evolution of the selfing syndrome: anther orientation and herkogamy together determine reproductive assurance in a self-compatible plant

Capacity for autonomous self-fertilization provides reproductive assurance, has evolved repeatedly in the plant kingdom, and typically involves several changes in flower morphology and development (the selfing syndrome). Yet, the relative importance of different traits and trait combinations for efficient selfing and reproductive success in pollinator-poor environments is poorly known. In a series of experiments, we tested the importance of anther-stigma distance and the less studied trait anther orientation for efficiency of selfing in the perennial herb Arabis alpina. Variation in flower morphology among eight self-compatible European populations was correlated with efficiency of self-pollination and with pollen limitation in a common-garden experiment. To examine whether anther-stigma distance and anther orientation are subject to directional and/or correlational selection, and whether this is because these traits affect pollination success, we planted a segregating F2 population at ...自主自交能力可为植物提供生殖保障，该性状在植物界中多次独立演化，且通常伴随花形态与发育模式的多项改变，即自交综合征（selfing syndrome）。然而，在传粉者匮乏的环境中，不同性状及其组合对高效自交与生殖成功的相对重要性，目前仍未得到充分阐明。本研究通过一系列实验，以多年生草本植物高山南芥（Arabis alpina）为研究对象，探究了花药-柱头间距（anther-stigma distance）与此前研究较少关注的花药朝向（anther orientation）这两个性状对自交效率的影响。在一项同质园（common-garden）实验中，欧洲8个自交亲和种群的花形态变异，与自交授粉效率以及花粉限制程度均存在相关性。为探究花药-柱头间距与花药朝向是否受到定向选择或相关选择的作用，以及这种选择是否源于上述性状对传粉成功的影响，我们将一个分离F2群体种植于……