J Plant Ecol ›› 2021, Vol. 14 ›› Issue (3): 451-464 .DOI: 10.1093/jpe/rtab002

• Research Articles • Previous Articles     Next Articles

In nomen omen: the effect of flower distance on female reproductive success of the lax-flowered orchid Anacamptis laxiflora (Orchidaceae)

Giovanni Scopece1,*, Nicola Criscuolo2, and Salvatore Cozzolino1   

  1. 1 Department of Biology, University Federico II, Complesso Universitario MSA, via Cinthia, I-80126 Naples, Italy, 2 Department of Environmental Systems Science, ETH Zürich, Zürich, Switzerland

    *Corresponding author. E-mail: giovanni.scopece@unina.it
  • Received:2020-07-28 Revised:2020-12-27 Accepted:2021-01-12 Online:2021-01-15 Published:2021-06-01



In multiflowered species, the architecture of inflorescences is of primary importance in shaping plant attractiveness. The aim of this study was to disentangle the role of inflorescence traits in plant female reproductive success and pollination patterns along the inflorescence in the lax-flowered orchid Anacamptis laxiflora, a terrestrial species exploiting a deceptive pollination strategy. We also evaluated whether the relationship between inflorescence traits and female reproductive success was modified by the height of surrounding vegetation and/or by population density.


We delimited experimental plots in a natural population of A. laxiflora. We tallied the individuals within each plot and categorized low-density plots and high-density plots; then, in part of the plots we manually removed surrounding grass thus producing an equal number of plots with high grass and low grass. Within these plots, we recorded inflorescence traits and female reproductive success (i.e. the number of fruit and their position along the inflorescence). We analyzed these data using generalized linear mixed-effects models (GLMMs) and calculated selection gradients.

Important Findings

We found that all the investigated inflorescence traits influenced female reproductive success. In particular, our GLMMs showed that ‘average flower distance’ was the best predictor for shaping reproductive success patterns. We detected significant positive selection on the investigated inflorescence traits, but these selective trends were strictly linked to both the height of the surrounding vegetation and the population density, suggesting a significant influence of local environmental context in shaping selective patterns. Female reproductive success was not linked to the position of flowers along the inflorescence, suggesting that pollinators visit flowers randomly along the inflorescence without a detectable preference for a specific part. This study highlights the importance of inflorescence traits in shaping female reproductive success of multiflowered deceptive orchids, and confirms a primary role for the environmental context in modifying pollinator-mediated selection patterns.

Key words: food-deceptive orchids, inflorescence, phenotypic selection, plant fitness, pollinator-mediated selection

论花距对花序松散的倒距兰(Anacamptis laxiflora)雌花繁殖成功率的影响
对多花物种而言,花序结构是塑造植物吸引力的首要因素。本研究旨在揭示花序性状对植物雌花繁殖成功率的影响,以及倒距兰(Anacamptis laxiflora,一种采用欺骗性授粉策略的陆生物种)花序上的授粉规律。我们还探究了花序性状与雌花繁殖成功率之间的关系是否会因为周围植被的高度和/或种群密度的影响而改变。我们在一个天然的倒距兰种群中划定了实验区块,对每个区块内的植株个体进行计数,并将各区块按低密度和高密度进行分类;随后,在部分区块内,我们人工清除了植株周围的杂草,从而产生了同等数量的高草丛区块和低草丛区块。我们统计了这些区块中的花序性状和雌花繁殖成功率(即果实数量及其在花序上的位置),使用广义线性混合模型(GLMMs)对统计数据进行了分析,并计算出了选择梯度。我们发现所研究的所有花序性状均对雌花繁殖成功率造成了影响。特别是GLMMs的结果表明,“平均花距”是对繁殖成功规律的最佳预测因子。我们所研究的花序性状受到显著的正向选择作用,但是这些选择趋势与周围植被的高度和种群密度都紧密相关,表明当地环境背景对选择规律的形成有显著影响。雌花繁殖成功率与花朵在花序上的位置无关,这说明传粉者在花序上随机选择花朵,未见其对花序特定部位的偏好。本项研究突显出花序性状对于多花、具有欺骗性的兰花雌花繁殖成功的重要性,并证实了环境背景在调节传粉者介导的选择规律中的主导作用。

关键词: 食物欺骗性兰花, 花序, 表型选择, 植物适应性, 传粉者介导的选择