Data from: Correlated evolution of mating system and floral display traits in flowering plants and its implications for the distribution of mating system variation

Reduced allocation to structures for pollinator attraction is predicted in selfing species. We explored the association between outcrossing and floral display in a broad sample of angiosperms. We used the demonstrated relationship to test for bias against selfing species in the outcrossing rate distribution, the shape of which has relevance for the stability of mixed mating.

Relationships between outcrossing rate, flower size, flower number and floral display, measured as the product of flower size and number, were examined using phylogenetically independent contrasts. The distribution of floral displays among species in the outcrossing rate database was compared with that of a random sample of the same flora.

The outcrossing rate was positively associated with the product of flower size and number; individually, components of display were less strongly related to outcrossing. Compared with a random sample, species in the outcrossing rate database showed a deficit of small floral display sizes.

We found broad support for reduced allocation to attraction in selfing species. We suggest that covariation between mating systems and total allocation to attraction can explain the deviation from expected trade-offs between flower size and number. Our results suggest a bias against estimating outcrossing rates in the lower half of the distribution, but not specifically against highly selfing species.

自交物种中，用于吸引传粉者的结构资源投入降低是已被学界预测的现象。本研究基于被子植物的大样本，探究了异交率与花展示（floral display）之间的关联。我们利用已验证的二者关系，检验异交率分布中是否存在针对自交物种的偏倚——该分布的形状与混合交配系统的稳定性密切相关。

本研究采用系统发育独立对比（phylogenetically independent contrasts）方法，分析了异交率、花大小、花数量以及以花大小与花数量乘积定义的花展示之间的关联。我们将异交率数据库中各物种的花展示分布，与同植物区系的随机样本分布进行了对比。

异交率与花大小和花数量的乘积呈显著正相关；单独而言，花展示的两个组成部分（花大小、花数量）与异交率的相关性较弱。与随机样本相比，异交率数据库中的物种存在小花展示规模的缺失情况。

本研究结果广泛支持了自交物种中传粉吸引结构资源投入降低的预测。我们认为，交配系统与传粉吸引总资源投入之间的协同变异，能够解释花大小与花数量之间预期权衡关系的偏离。本研究结果还显示，异交率分布的下半区间存在异交率估算偏倚，但并未发现针对高度自交物种的特定偏倚。