University of Nevada Reno, Department of Biology, 1664 N. Virginia St., Reno, NV, USA.
University of Nevada Reno, Department of Natural Resources and Environmental Science 1664 N. Virginia St., Reno, NV, USA.
Curr Biol. 2019 Jul 22;29(14):R679-R680. doi: 10.1016/j.cub.2019.05.046.
Plants often compete in a marketplace that involves the exchange of floral rewards for pollination service [1]. This marketplace is frequently viewed as revolving around a single currency, typically nectar. While this focus has established pollinators such as bees as classic models in foraging ecology, in reality many plants provide both pollen and nectar, which vary in composition within and across species [2]. How this complexity impacts interactions between plants, pollinators, and co-flowering competitors is unknown. We explored how variation in two axes of reward chemistry - nectar sugar and pollen alkaloid content - impacted competition for bumblebee visits. The effect of variation in one reward depended on the presence and quality of the other - bees discriminated against flowers with more defended pollen when all flowers offered the same quality nectar. However, bees preferred flowers with highly defended pollen when they offered higher quality nectar, suggesting that attractive nectar can overcome the ecological costs of defended pollen. Recognizing the interdependence of these floral currencies may help identify traits that drive indirect interactions between plants and clarify broader evolutionary patterns of floral reward phenotypes.
植物经常在一个涉及花卉报酬交换授粉服务的市场中竞争[1]。这个市场通常被认为是以单一货币为中心，通常是花蜜。虽然这种关注使蜜蜂等传粉者成为觅食生态学中的经典模型，但实际上许多植物既提供花粉又提供花蜜，而且在物种内和物种间的组成上存在差异[2]。这种复杂性如何影响植物、传粉者和同花期竞争者之间的相互作用尚不清楚。我们探讨了奖励化学物质的两个轴 - 花蜜中的糖和花粉中的生物碱含量 - 的变化如何影响大黄蜂访问的竞争。一种奖励的变化的影响取决于另一种奖励的存在和质量 - 当所有花朵提供相同质量的花蜜时，蜜蜂会歧视花粉防御性更强的花朵。然而，当它们提供更高质量的花蜜时，蜜蜂更喜欢花粉防御性强的花朵，这表明有吸引力的花蜜可以克服防御性花粉的生态成本。认识到这些花卉货币的相互依存关系可能有助于确定驱动植物间间接相互作用的特征，并阐明花卉报酬表型的更广泛进化模式。
