2.3. Plants traits
We collated information on seven plant characteristics: type of breeding system (i.e. extent of self-compatibility and autonomous selfing), level of dichogamy, clonality, amount of nectar reward, number of open flowers, and plant specialization on pollinator functional groups. Data on the extent of self-compatibility and autonomous selfing for 18 of the target species were obtained from our greenhouse pollination experiment (Bartoš et al. 2020). Data on dichogamy were extracted from the Biolflor database (Klotz et al. 2002) and transformed from the original seven categories to a continuous variable ranging from 0 to 0.5, with the value 0.5 denoting an absence of dichogamy (i.e. simultaneous presence of male and female organs). The missing data on breeding type (four cases) and level of dichogamy (two cases) were replaced by average values from the whole dataset. The clonal multiplication (i.e. number of vegetative offspring per maternal shoot per year) was extracted from the Clo-Pla database (Klimešová et al. 2017). The daily sugar production in nectar reward was determined in the field for 15 flowers per plant species. Flowers from different plant specimens were bagged at their full anthesis for 24 hours after which nectar was extracted. Nectar was washed with distilled water using a 100µl Hamilton syringe and stored in a refrigerator prior to freezing, following Morrant et al. (2008). The amount of nectar sugars was quantified by high-performance liquid chromatography (HPLC) using the ICS-3000 system (Dionex), with an electrochemical detector and CarboPac PA 1 column. The nectar production was expressed in milligrams of nectar sugars per flower/day. Mean number of open flowers per species was calculated from 60 specimens per species from three meadows in the study region.
Plant functional specialization was expressed as the number of pollinator functional groups that touched anthers and/or stigmas during foraging. The pollinator spectrum for each plant species was counted from videos recorded in the field using portable video systems of VIVOTEK (IB8367-T) and MILESIGHT (MS-C2962-FPB-IR60m) cameras. In total, 72 hours (equally covering day and night) per plant species were recorded in three different localities in the vicinity of the study area. All pollinators were split into eleven functional groups: ants, beetles, bumblebees, butterflies, honeybees, hoverflies, long-tonged flies, moths, other bees, other flies, and other hymenopterans. Groups which were represented by fewer than 3 visitors per plant species were excluded from the analyses, to avoid random visits.