Although pollination networks between plants and flower visitors are diverse and flexible, seed production of many plant species is restricted by pollen limitation. Obligate outcrossers often suffer from low pollinator activity or severe interspecific competition for pollinator acquisition among co‐flowering species. This study focused on seasonal changes in plant–flower visitor linkages in an alpine ecosystem and examined whether and how this seasonality affected the seed‐set of Primula modesta, a self‐incompatible distylous herb having long‐tubed flowers. First, we recorded the linkages between plants and flower visitors along the snowmelt gradient. Then, pollination experiment was conducted to estimate the degree of pollen limitation over the course of flowering season of P. modesta. Flower visitors were classified by their tongue length based on the morphological matching with P. modesta flowers. As the season progressed, plant–visitor linkages became more diverse and generalized, and the visitation frequency to P. modesta flowers increased. In the later part of the season, however, the seed set of P. modesta was significantly reduced due to severe pollen limitation, presumably because of increased competition for long‐tongued pollinators among co‐flowering species. The present study revealed that pollinator availability for specialist species may be restricted even when plant–visitor linkages are diverse and generalized as a whole. In the case of P. modesta, morphological matching and competition for pollinators might be the main factors explaining this discrepancy.

中文翻译：

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沿融雪梯度植物与花卉访客之间联系的时间变化和报春花传粉的授粉成功

尽管植物和花卉访客之间的授粉网络是多样且灵活的，但许多植物物种的种子生产受到花粉限制的限制。专心的异型交配经常遭受授粉媒介活性低或种间竞争激烈的授粉媒介习性。这项研究着眼于高山生态系统中植物与花卉访客联系的季节性变化，并研究了这种季节性是否以及如何影响报春花报春花的种子集，报春花报春花是一种不相容的，具长管状花的异味草本。首先，我们沿着融雪坡度记录了植物和花卉访客之间的联系。然后，进行授粉实验，以估计P.modesta花期整个花粉的限制度。。根据与P. modesta花的形态匹配，将花客按舌长分类。随着季节的发展，植物与植物之间的联系变得更加多样化和普遍化，对P. modesta花的探访频率也增加了。然而，在该季节的后期，由于严重的花粉限制，P。modesta的种子集明显减少，这可能是由于共同开花物种中对长舌传粉者的竞争加剧。本研究表明，即使植物与观察者之间的联系千差万别，而且总体上普遍存在，授粉媒介对特殊物种的利用也可能受到限制。在P.modesta的情况下，传粉媒介的形态匹配和竞争可能是解释这种差异的主要因素。