Higher seed number compensates for lower fruit set in deceptive orchids

1. Floral deception is widespread in orchids, with more than one third of the species being pollinated this way. The evolutionary success of deceptive orchids is puzzling, as species employing this strategy are thought to have low reproductive success (less flowers yielding fruits) because of low pollination rates. However, direct measurements of total seed production in orchids – which is a better measure of reproductive success – are scarce due to the extremely small size of their seeds. 2. Here, we quantified seed numbers in 1,015 fruits belonging to 48 orchid species from the Pannonian ecoregion (central Europe) and obtained fruit-set and thousand-seed weight data for these species from the literature. We used phylogenetic comparative methods to test the hypothesis that deceptive species should compensate for their lower fruit-set by having either more flowers, larger seeds or more seeds in a fruit. 3. Similarly to previous studies, we found that deceptive orchids have substantially...1. 花部欺骗策略在兰科植物中分布广泛，超过三分之一的兰科物种通过该方式完成传粉。具有欺骗性传粉策略的兰科植物的演化成功一直令人困惑，因为这类物种因传粉效率低下，被认为繁殖成功率较低（即座果率低，仅有少量花朵可发育为果实）。然而，由于兰科植物的种子体型极小，针对其种子总产量的直接测定数据十分匮乏——而种子总产量是衡量繁殖成功率的更优指标。 2. 本研究中，我们对取自中欧潘诺尼亚生态区的48个兰科物种的1015个果实内的种子数量进行了定量统计，并从公开文献中获取了这些物种的座果率与千粒重数据。我们采用系统发育比较分析方法，验证了如下假说：具有欺骗性传粉策略的物种，可通过增加单株花量、增大种子体积或提升单果种子数，来弥补其较低的座果率。 3. 与既往研究类似，我们发现具有欺骗性传粉策略的兰科植物显著