Data from: Mechanisms of male-male interference during dispersal of orchid pollen
Citation
Harder, Lawrence; Richards, Shane A.; Ågren, Jon; Johnson, Steven D. (2020), Data from: Mechanisms of male-male interference during dispersal of orchid pollen, Dryad, Dataset, https://doi.org/10.5061/dryad.41ns1rnc0
Abstract
Methods
We quantified massula dispersal in a glasshouse at the Ecological Field Station of Uppsala University at Skogsby on Öland, Sweden. Bees without A. morio pollinaria were captured while foraging near the Field Station and maintained in individual vials in a refrigerator. We also collected A. morio inflorescences with intact pollinaria and clean stigmas from a nearby population and placed them in water-filled vials for use in the experiment. On each donor inflorescence, we stained both pollinia of one flower by injecting rhodamine pink histochemical stain into the anther sacs with a syringe, which generally dyes all of a pollinium’s massulae. Stain was allowed to dry > 20 min before an inflorescence was used in the experiment. We also collected a neighboring flower from the inflorescence, for which we counted the massulae of one pollinium as an estimate of pollen availability in the stained flower. Massula production correlates very strongly between adjacent flowers within inflorescences (r = 0.971, P < 0.001, n = 18 plants). A bee was allowed to visit a donor flower and, if it removed the stained pollinaria, it was left for a minute to reorient before the experimental trial began. Only A. morio flowers were present in the glasshouse.
The experiment contrasted two types of trials during which a bee with two stained donor pollinia visited a sequence of recipient flowers. For the 16 emasculated (E) trials, the pollinaria had been removed from all recipient flowers, precluding pollen interference. In contrast, for the 15 intact (I) trials, all recipient flowers had unstained pollinaria that could transfer to the bee and interfere with dispersal of stained donor pollen that the bee already carried. During intact trials, we allowed about 1 min to elapse between visits to successive recipient flowers to permit pollinarium reorientation. To minimize unintended effects of trial sequence, day, time of day, etc., we conducted the two trial types in almost strictly alternating order. Except for one intact trial during which the bee escaped after visiting 10 recipient flowers, bees were caught at the end of each trial and placed in vials in a refrigerator to facilitate removal and counting of both recipient pollinaria and remaining stained massulae on the donor pollinarium (if still present). Most bees participated in only one trial each. We examined the stigmas of all visited recipient flowers with a dissecting microscope (24x) and counted both the stained (donor) and, if applicable, unstained (recipient) massulae. For intact trials, we also recorded the number of pollinaria removed from recipient flowers to quantify changes in a bee’s maximal (cumulative) pollinarium load. Total loss of donor massulae was estimated as the difference between the initial number (based on an adjacent unvisited donor flower) and the sum of donor massulae deposited on all recipient stigmas and those remaining on the bee at the end of a trial.
Usage Notes
Variable | Description |
Trial_type | Type of trial (Intact pollinaria in recipient flowers or Emasculated recipient flowers) |
Trial | Trial number |
M_init | Initial number of donor massulae |
R | Final number of donor pollinaria on bee |
Visit | Sequence number of recipient flower in trial |
Deposition | Number of donor massulae deposited on stigma of recipient flower |