Department of Ecology and Evolution, State University of New York, Stony Brook, New York 11794-5245 USA; and.
Am J Bot. 2002 Jan;89(1):111-8. doi: 10.3732/ajb.89.1.111.
Plants that experience variation in pollinator visitation rates or fluctuations in weather conditions may be expected to have evolved homeostatic mechanisms that regulate their nectar offerings, thereby providing a more constant reward to the pollinators. A limited degree of such nectar homeostasis is reported here for Penstemon. First, nectar removal stimulates replenishment: when nectar was removed hourly for 6 h from P. speciosus, twice as much nectar was secreted cumulatively as when nectar was removed only at the beginning and end of the same 6-h period. Second, replacing artificial nectar in the nectaries of P. speciosus prevents replenishment. Third, the hummingbird-adapted P. barbatus made more nectar before leveling off than the bee-adapted P. strictus. Our work and previous studies with other plants imply mechanisms for dynamic regulation of nectar offerings, at least within broad limits. We speculate about the proximate physiology underlying this behavior and its evolutionary significance.
那些经历传粉者访问率变化或天气条件波动的植物，可能已经进化出了调节花蜜供应的体内平衡机制，从而为传粉者提供更稳定的奖励。这里报告了一种有限程度的这种花蜜体内平衡，Penstemon 就是一个例子。首先，花蜜的消耗会刺激补充：当从 P. speciosus 中每小时取出花蜜 6 小时时，累积分泌的花蜜量是在同一 6 小时期间仅在开始和结束时取出花蜜的两倍。其次，在 P. speciosus 的蜜腺中替换人工花蜜会阻止补充。第三，适应蜂类的 P. strictus 比适应蜂类的 P. barbatus 在达到稳定状态之前分泌出更多的花蜜。我们的工作以及之前对其他植物的研究表明，至少在广泛的范围内，存在动态调节花蜜供应的机制。我们推测了这种行为背后的近似生理学及其进化意义。
