PDF(Pubmed)
Abstract：
Floral scent, a key mediator in plant-pollinator interactions, varies not only among plant species, but also within species. In deceptive plants, it is assumed that variation in floral scents and other traits involved in pollinator attraction is maintained by negative frequency-dependent selection, i.e., rare phenotypes are more attractive to pollinators and hence, have a higher fitness than common phenotypes. So far, it is unknown whether the rarity of multivariate and/or continuous floral scent traits influences the pollination success of flowers. Here, we tested in the deceptive orchid Cypripedium calceolus, whether flowers with rarer scent bouquets within a population have a higher chance to getting pollinated than flowers with more common scents. We collected the scent of more than 100 flowers in two populations by dynamic headspace and analyzed the samples by gas chromatography coupled to mass spectrometry (GC/MS). From the same flowers we also recorded whether they set a fruit or not. We introduced rarity measures of uni- and multivariate floral scent traits for single flowers, which allowed us to finally test for frequency-dependent pollination, a prerequisite for negative frequency-dependent selection. Our results do not show rarity has an effect on the likelihood to set fruits in neither of the two populations and in none of the scent characteristics analyzed. Hence, there is no evidence of negative frequency-dependent pollination mediated by the floral scent of C. calceolus. We discuss that our approach to determine rarity of a scent is applicable to any univariate or multivariate (semi)quantitative trait.
摘要：
花香,植物-传粉媒介相互作用的关键媒介，不仅在植物物种之间有所不同，而且在物种内。在欺骗性植物中，假设通过负频率依赖性选择来维持与授粉媒介吸引有关的花卉气味和其他性状的变化，即，稀有表型对传粉者更有吸引力，因此，具有比常见表型更高的适应性。到目前为止,尚不清楚多元和/或连续花香性状的稀有性是否会影响花朵的授粉成功。这里,我们在欺骗性的兰花中进行了测试，与具有更常见气味的花朵相比，具有更稀有气味的花朵是否有更高的机会授粉。我们通过动态顶空收集了两个种群中100多朵花的气味，并通过气相色谱-质谱（GC/MS）分析了样品。从同样的花朵中，我们还记录了它们是否结了果实。我们引入了单花和多变量花香性状的稀有性度量，这让我们最终测试了频率依赖性授粉，负频率依赖性选择的先决条件。我们的结果没有表明稀有性对这两个种群中没有一个和没有分析气味特征的结果的可能性有影响。因此，没有证据表明，由calceolus的花香介导的负频率依赖性授粉。我们讨论了确定气味稀有性的方法适用于任何单变量或多变量（半）数量性状。
