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Data from: Seed fate in ant-mediated dispersal: Seed dispersal effectiveness in the Ectatomma ruidum (Formicidae) - Zanthoyxlum ekmanii (Rutaceae) system

Citation

Ruzi, Selina A.; Suarez., Andrew V. (2022), Data from: Seed fate in ant-mediated dispersal: Seed dispersal effectiveness in the Ectatomma ruidum (Formicidae) - Zanthoyxlum ekmanii (Rutaceae) system, Dryad, Dataset, https://doi.org/10.5061/dryad.t1g1jwt4c

Abstract

Plants are often dispersal limited relying on passive or active agents to find suitable microhabitats for germination. Seeds of pioneer tree species, for example, require light gaps for growth but have short median dispersal distances and often do not provide a food reward to encourage animal dispersal. Zanthoxylum ekmanii seeds are frequently moved by ants but evaluating the effectiveness of ant-mediated seed removal requires knowledge of the species moving the seeds, how far they are moved, and the deposition site. To assess the effectiveness of ants as seed dispersers of Z. ekmanii, we utilized the seed dispersal effectiveness framework. We tracked the movement of seeds from caches on the forest floor, revealing that foragers of Ectatomma ruidum moved 32.8% of seeds an average first distance of 99.8 cm with 68.3% of those seeds taken into a colony. The quality of deposition location was assessed using a seedling emergence study where freshly germinated seeds were buried at different depths. Seedlings were primarily able to emerge from the shallowest depths. Wax castings of E. ruidum colonies demonstrated that seeds brought into the colony were deposited in chambers that had larvae present and experienced more damage than seeds unhandled by ants. Foragers, however, did not have a strong enough bite force to rupture Z. ekmanii seeds likely because their muscle morphology is not structured to maximize force generation. Overall, E. ruidum may help fine tune deposition location, incorporating seeds into the topsoil, though few seeds will likely emerge if soil bioturbation is low.

Methods

The data was collected at five sites on Barro Colorado Island (BCI) and Parque Soberania near Gamboa in the Republic of Panama. Data on seed removal, distance moved, and deposition location of Zanthoxylum ekmanii seeds and the ants (primarily belonging to Ectatomma ruidum) were collected in the 2015 and 2016 dry seasons on BCI. These data were collected by observed seed caches consisting of 5 seeds placed on the soil surface for 2 hours. A total of 25 caches were placed. Data on burial depth from wax casts of Ectatomma ruidum colonies was collected in 2015 and 2016 from Parque Soberania. Some of these colonies were provisioned with Z. ekmanii seeds prior to being wax casted. These seeds were recollected and compared to seeds that have presumably never come into contact with ants to assess the amount of damage casued by ants to seeds. Bite force data was collected using modified peizoelectric sensor and software on 4 E. ruidum workers from colonies found in Parque Soberania. Data from the seedling emergence study were collected in the 2018 dry season in an ambient air greenhouse on BCI. These data were collected by buring freshly germinated seeds at either 0, 2, 5, or 7cm in sieved soil and recording whether seedlings were able to emerge.

Usage Notes

To accesss the R project associated with this data deposition please see https://github.com/sruzi24/Ruzi_and_Suarez_seed_short_term_seed_fate

Funding

National Science Foundation, Award: 1701501

National Science Foundation, Award: 1906242

Smithsonian Tropical Research Institute