Data for: Evaluating the influences of floral traits and pollinator generalism on α and β diversity of heterospecific pollen on stigmas

Study system Heterospecific pollen receipt was studied in 59 insect-pollinated flowering plant species from 26 families (Fig. 2 and Table S1) in the serpentine seep communities at the McLaughlin Natural Reserve in California, USA (38.8582º N, 122.4093º W). We focused on three seep communities (hereafter referred to as ‘seeps’: ‘BS’, ‘RHA’, ‘TPW’) that were less than 5 km apart (for locations see Koski et al., 2015). Flowering within the three seeps is highly synchronized between April–June due to seasonal drying (Arceo-Gómez et al., 2019; Wei et al., 2021). Pollinators are a diverse set of bees, flies, butterflies, moths, ants, wasps, beetles, and hummingbirds (Koski et al., 2015; Wei et al., 2021). Style sampling and pollen identification Each week during April 21 to June 25, 2016, we collected styles from spent (wilted) flowers of each species in the three seeps. At each sampling day at a seep, we collected multiple style samples for each species. Each sample contained three styles (stigmas) from different individuals of the same species that were stored together in 70% ethanol in a 1.5-ml microcentrifuge tube. For species with very small flowers, whole flowers were collected in the field and three styles were excised in the laboratory. From the vast collection of samples, we used a stratified random subsampling to achieve 9 samples (range 4–11) per species at each of the three seeps for heterospecific pollen characterization (total of 27 samples per species). This sampling effort was sufficient to capture the γ diversity of HP deposited on stigmas for each plant species at individual seeps (i.e., similar observed vs. asymptotic HP richness; Table S1). Out of the 59 plant species, 25 species had style samples from all three seeps, whereas 18 and 16 species had samples from two seeps and one seep, respectively (Table S1). To characterize the HP communities received by stigmas for each plant species at a seep, we acetolyzed individual samples (three stigmas and their pollen grains) and counted pollen grains with the aid of a hemocytometer. Each pollen grain was identified to species based on a pollen library created from the plants in the seeps (Hayes et al., 2022). The pollen that was not identified or not distinguishable at the species level (0.6% of all pollen scored) were clustered into congener or morphospecies groups (Wei et al., 2021).研究系统 本研究于美国加利福尼亚州麦克劳克林自然保护区（McLaughlin Natural Reserve）的蛇纹岩渗流群落（serpentine seep communities）中开展，针对来自26个科的59种虫媒显花植物的异交花粉接收（heterospecific pollen receipt）情况展开研究（见图2及附表S1）。本研究聚焦于彼此间距不足5 km的3处渗流群落（下文简称"渗流点"：BS、RHA、TPW），其具体位置详见Koski等（2015）的研究。受季节性干旱影响，3处渗流点的开花期高度同步，集中于4月至6月（Arceo-Gómez et al., 2019；Wei et al., 2021）。该区域传粉者类群多样，涵盖蜂类、蝇类、蝶类、蛾类、蚁类、胡蜂类、甲虫及蜂鸟（Koski et al., 2015；Wei et al., 2021）。 采样方法与花粉鉴定 2016年4月21日至6月25日期间，我们每周从3处渗流点各物种的凋萎花中采集花柱（styles）。在每个渗流点的每个采样日，我们为每个物种采集多份花柱样本：每份样本包含同一物种不同个体的3枚花柱（柱头（stigmas）），将其共同存放于装有70%乙醇的1.5 ml微量离心管（microcentrifuge tube）中。对于花型极小的物种，我们先在野外采集整朵花，再于实验室中切取3枚花柱。 从海量采集的样本中，我们采用分层随机抽样法，为3处渗流点的每个物种各获取9份样本（区间为4~11份）以开展异交花粉（heterospecific pollen, 下文简称HP）表征分析，最终每个物种总计获得27份样本。该采样力度足以覆盖单个渗流点中各植物柱头所承载的HP γ多样性（γ diversity）（即观测到的HP丰富度与渐近丰富度相近；附表S1）。在59种植物中，25个物种在3处渗流点均有采样样本，18个和16个物种分别仅在2处及1处渗流点有采样样本（附表S1）。 为表征单个渗流点中各植物物种柱头所接收的HP群落组成，我们对每份单独样本（含3枚柱头及其携带的花粉粒）进行乙酰解处理，并借助血球计数板（hemocytometer）对花粉粒进行计数。每一粒花粉均基于该渗流点内植物所构建的花粉库进行物种水平鉴定（Hayes et al., 2022）。未被鉴定或无法在物种水平区分的花粉（占所有计数花粉的0.6%）被归类为同属类群或形态种（morphospecies）（Wei et al., 2021）。