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.