DOI: 10.5061/dryad.s4mw6m9cf
title: Evaluation of seed-dispersal services by ants at a temperate pasture: Results of direct observations in an ant suppression experiment

description: Ant dispersal Ants disperse seeds of many plant species adapted to
 myrmecochory. While advantages of this ant–plant mutualism for
 myrmecochorous plants (myrmecochores) have been previously studied in
 temperate region mostly in forests, our study system was a pasture.
 Moreover, we used a unique combination of observing the effect of
 ant‐activity suppression on ant dispersal and comparison of the
 contribution of ant and unassisted dispersal to the distance from mother
 plant. We established plots without and with ant‐activity suppression
 (enclosures). We offered diaspores of a myrmecochorous (Knautia arvensis),
 and a non‐myrmecochorous (Plantago lanceolata) species in a choice test
 and followed ants carrying diaspores during days and nights (focus of
 previous studies was on diurnal dispersal). We measured frequency and
 distances of ant dispersal and compared them with unassisted dispersal
 recorded using sticky trap method. The dispersal frequency was lower in
 enclosures (3.16 times). Ants strongly preferred diaspores of the
 myrmecochore to non‐myrmecochore with 586 and 42 dispersal events,
 respectively (out of 6400 diaspores of each species offered). Ant
 dispersal resulted in more even and on average longer distances (maximum
 almost tenfold longer, 994 cm) in comparison to unassisted dispersal. Ant
 dispersal altered the distribution of distances of the myrmecochore from
 roughly symmetric for unassisted dispersal to positively skewed. Ants
 dispersed heavier diaspores farther. Ants dropped the majority of
 diaspores during the dispersal (which reduces clustering of seeds), while
 several (11%) were carried into anthills. Anthills are disturbed
 microsites presumably favorable for germination in competitive habitats.
 Ants provided non‐negligible dispersal services to
 myrmecochorous K. arvensis but also, to a lesser extent,
 of non‐myrmecochorous P. lanceolata. Unassisted dispersal A
 sticky trap of the same size as the experimental plots of the cafeteria
 experiment (3 m × 3 m) was used to record unassisted dispersal (i.e.,
 without any biotic dispersal agent, mostly by gravity and additionally
 wind). We used linoleum covered with insect glue to trap the falling
 diaspores. Five full‐sized individuals (with majority of infructescences
 with mature seeds) of K. arvensis were fixed in a water container in the
 center of the plot for approximately 10 days. The procedure was repeated
 five times during July and August. The distances of trapped diaspores were
 measured in the same manner as in the case of ant dispersal, thus the
 dispersal by ants and unassisted dispersal can be compared.
description: In cafeteria experiments, we compared the frequency and distance
 of seed dispersal between enclosures and controls and between the
 myrmecochorous and the non‐myrmecochorous species. The cafeteria
 experiment took place at eight observational days in two periods—4 days
 with favorable weather between July 1 and 7 and August 22–292,019. Each
 day, 50 diaspores of each species were exposed to ants on a bait station
 (cardboard squares 6 cm × 6 cm) placed in the center of each of the 16
 plots. Diaspores of the two species were placed in a mixture in a single
 layer so ants were able to choose among them (between and within species)
 according to their attractiveness. After the start of
 the experiment, approximately noon, we repeatedly checked the position of
 seeds during dispersal and placed a marker where it was found (so the
 diaspore can be carried farther by the same or different ant). Diaspores
 were covered with fluorescent powder and approximately four people rotated
 among plots (time spent on plots as even as possible) and observed ants
 carrying diaspores during days and in ultraviolet light during nights. The
 next morning the distances from the bait station of for both unique and
 ongoing dispersal events were measured, and all the present diaspores were
 collected (newly dispersed diaspores were also searched for and their
 distances measured). We distinguished two types of dispersal events:
 unique dispersal events with the diaspore present (i.e., found on the
 ground or seen to be carried into the anthill) and second type with
 diaspore absent at the last observation at the time of
 collection.
description: # Dispersal distances: ant and unassisted dispersal
 [https://doi.org/10.5061/dryad.s4mw6m9cf](https://doi.org/10.5061/dryad.s4mw6m9cf) The dataset contains dispersal distances gained by one myrmecochorous (*Knautia arvensis*) and one non-myrmecochorous (*Plantago lanceolata*) species. We distinguished two types of dispersal events: unique dispersal events with the seed present (i.e., found on the ground or seen to be carried into the anthill) and second type with seed absent at the last observation at the time of collection. These data we named ongoing dispersal events as one seed might be recorded repeatedly as more dispersal events during the dispersal process. The ongoing dispersal events mean that seeds were later dispersed to their final destination with a greater (often unknown) distance where they were either not found (e.g., inside the anthill) or found and counted as unique dispersal events, thus one seed can be counted multiple times in the ongoing dispersal events. The dispersal was observed in two plot types controls and enclosures (plots with ant activity supression) In addition, we quantified the unassisted dispersal of the myrmecochore by a sticky trap method. We used five consecutive measurements of sticky traps using each time five plants in the centre of a sticky trap. Afterwards, we measured distances of unassisted dispersal. The dispersal frequency was lower in enclosures with ant-activity suppression. Ants strongly preferred seeds of myrmecochores to non- myrmecochores. There were 586 seed dispersal events of myrmecochorous and 42 dispersal events of the non-myrmecochorous species out of 6400 seeds of each plant species offered to ants. Ant dispersal resulted in more even and on average longer distances (maximum distance tenfold longer, almost 10 m) in comparison to unassisted dispersal. ## Description of the data and file structure There are data on dispersal by ants in the excel file in the first list named "dispersal events". Plot number (1 - 16), number of observational day (1-8), dispersal distance in cm, seed present yes/no (i.e. unique and ongoing dispersal event data set respectively), treatment (control/enclosure) and species (myrmecochore/Plantago) are present. Further, data on unassisted dispersal in the second list named "sticky traps". In this list distances in cm and number of measurement (1-5) is present.