Pollination is an important ecological process. However, plant and pollinator needs are not always met. Commonly, pollen limitation reduces seed set or bees experience nectar dearth. Using a cost-benefit approach, we show that natural selection will lead to lower nectar production when pollinators are abundant, and vice-versa. At the community level, competition among plants for pollinators causes positive feedback that exacerbates pre-existing seasonal imbalances between nectar supply and demand. When pollinators are scarce, plants will be selected to produce more nectar to outcompete other plants in attracting pollinators, and when pollinators are abundant, plants will be selected to produce less nectar. We suggest ways to test this positive feedback hypothesis and note that evidence for seasonal variation in nectar availability provides preliminary empirical support. If correct, our hypothesis indicates that pollination faces a particular challenge in balancing nectar supply with pollinator demand and is a further example of the underappreciated role of positive feedback in ecology and evolution.

中文翻译：

---

植物和传粉者：自然选择会导致花蜜供需失衡吗？

授粉是一个重要的生态过程。然而，植物和传粉媒介的需求并不总能得到满足。通常，花粉限制会减少种子结实或蜜蜂缺乏花蜜。我们使用成本效益方法表明，当传粉媒介丰富时，自然选择会导致花蜜产量降低，反之亦然。在社区层面，植物之间对传粉媒介的竞争会导致正反馈，从而加剧花蜜供需之间预先存在的季节性失衡。当传粉媒介稀少时，植物将被选择产生更多的花蜜以在吸引传粉媒介方面胜过其他植物，而当传粉媒介丰富时，植物将被选择产生更少的花蜜。我们提出了测试这种正反馈假设的方法，并注意到花蜜可用性季节性变化的证据提供了初步的实证支持。如果正确，我们的假设表明授粉在平衡花蜜供应与授粉媒介需求方面面临特殊挑战，并且是正反馈在生态学和进化中的作用被低估的另一个例子。