J Plant Ecol ›› 2021, Vol. 14 ›› Issue (4): 580-590.DOI: 10.1093/jpe/rtab012

• Research Articles • Previous Articles     Next Articles

Floral biology of Salvia stachydifolia, a species visited by bees and birds: connecting sexual phases, nectar dynamics and breeding system to visitors’ behaviour

Camila N. Barrionuevo, Santiago Benitez-Vieyra and Federico Sazatornil*   

  1. Laboratorio de Ecología Evolutiva y Biología Floral, Instituto Multidisciplinario de Biología Vegetal (Universidad Nacional de Córdoba— CONICET), CC 495 (X5000ZAA), Córdoba, Argentina

    *Corresponding author. E-mail: federicosaza@gmail.com
  • Received:2020-04-24 Revised:2020-07-19 Accepted:2021-01-25 Online:2021-02-13 Published:2021-08-01

Abstract:

Aims

Adaptive convergence in floral phenotype among plants sharing a pollinator guild has been acknowledged in the concept of pollination syndrome. However, many plants display traits associated with a given syndrome, but are visited by multiple pollinators. This situation may indicate the beginning of a pollinator shift or may result in a stable situation with adaptations to different pollinators. In Salvia stachydifolia, a previous study suggested that flower shape is optimized to maximize the contribution to pollination of bees and hummingbirds. Here, we studied three additional aspects of its floral biology: sexual phases, nectar dynamics and breeding system, and examined their connection with pollinators’ behaviour to explore the presence of adaptations to bee and/or hummingbird pollination.

Methods

Using a greenhouse population, we applied five pollination treatments to characterize breeding system. To determine sexual phases, we recorded flower opening, anther dehiscence, corolla fall and stigma receptivity. Additionally, we characterized nectar volume and concentration dynamics along the day. Finally, to determine pollinator assemblage and visitation patterns, we performed field observations and recorded pollinators’ behaviour.

Important Findings

Salvia stachydifolia was partially protandrous and self-compatible, but open-pollinated plants attained the highest reproductive success, suggesting that reproduction is mainly dependent on pollinator activity. Bombus opifex bumblebees were the most frequent visitors, but Sappho sparganura hummingbirds dominated visits early in the morning and at dusk. Nectar was typical of bumblebee pollination. We suggest that the bee–hummingbird mixed visitation constitutes an unstable evolutionary situation, making S. stachydifolia an ideal system to understand the ecological circumstances in which pollination shifts occur.

Key words: Salvia, sexual phases, nectar dynamics, breeding system, pollinator behaviour

摘要:
一种由蜂类和鸟类传粉的鼠尾草属植物的花生物学:建立了有性阶段、花蜜动态过程和 繁育系统与访花行为的联系
在对传粉综合征的认知过程中,人们已经意识到共享某类传粉媒介的植物间的花表型中存在着适应性趋同的现象。然而,虽然许多植物都表现出了与特定综合征相关的性状,但它们的访花传粉者却不止一种。这种情况可能意味着传粉媒介的变化,或者可能形成了一种可适应不同传粉媒介的稳定情况。此前在鼠尾草属Salvia  stachydifolia 中开展的一项研究表明,该物种的花形状可以最大限度地提升蜜蜂和蜂鸟的传粉效果。在本文中,我们研究了该物种的花生物学的另外3个方面:有性阶段、花蜜动态过程和繁育系统,并探讨了它们与传粉者行为之间的联系,以了解该物种在这3个方面上对蜜蜂和/或蜂鸟传粉的适应性变化。我们以某一温室种群为研究对象,对其在5种不同传粉方式下的繁育系统进行了刻画。为了确定有性阶段,我们分别对花开、花药开裂、花冠掉落和柱头可授性的情况进行了记录。此外,我们还对花蜜体积和浓度在一整天的动态变化进行了表征。最后,为了确定传粉者的 组成和访花模式,我们开展了实地观测并记录传粉者的行为。研究结果显示,S. stachydifolia 是部分雄蕊 先成熟且可自交,但自由授粉植株的繁殖成功率最高,表明繁殖过程主要取决于传粉者的活动。熊蜂属Bombus opifex (一种大黄蜂)是最常见的访花者,但在清晨和黄昏时占主导地位的访花者则是红尾慧星蜂鸟(Sappho sparganura)。花蜜常见于大黄蜂授粉的情况。我们认为蜜蜂-蜂鸟混合访花的模式构成了一种不稳定的进化情形,使得S.  stachydifolia 成为一种理想的研究对象,用以了解传粉媒介发生变化的生态环境。

关键词: 鼠尾草属(Salvia), 有性阶段, 花蜜动态过程, 繁育系统, 传粉者行为