Linking mechanism to pattern in community assembly: Ant-mediated seed dispersal in neotropical pioneer tree species

Dispersal is a fundamental process that affects all aspects of an organism’s biology including its distribution, genetic structure, demography, and reproduction. Ant-mediated seed dispersal has evolved multiple times in many biogeographical locations. Most research in this area has focused on myrmecochorous plants that are known to elicit seed dispersal by providing a specialized lipid rich food reward called an elaiosome attached to their seeds. However, seeds that are not known to have this food reward may still be attractive to ants. The aim of my dissertation was to describe the movement of seeds of Neotropical pioneer tree species that are not known to have elaiosomes by ants. For my research, I chose Neotropical pioneer tree species that are commonly found in the soil seed bank of Barro Colorado Island (BCI), Panama. The seeds of these tree species do not provide an elaiosome food reward to their ant removers, but varied in mass, primary dispersal mode (animal or wind), dormancy type (physical, physiological, or quiescent), and ability to persist in the soil in the absence of predators. My dissertation research from BCI had four parts: (1) I quantified seed removal rates among 12 Neotropical pioneer species in two locations of the soil seed bank (soil surface and two cm within the topsoil) to determine which seed characteristics best explained variation in seed removal rates. (2) I identified seed-removing ants and determined whether variation in ant communities / activity correlated with differences in seed removal rates among sites. (3) I determined that chemical cues played a role in mediating some seed-ant interactions for one Neotropical pioneer seed species. (4) Lastly, I estimated where and how far ants moved seed of one pioneer species, Zanthoxylum ekmanii Urb. (Alain) (Rutaceae) and whether the seeds would survive their deposition location. My dissertation research supports that ants will interact with seeds of some Neotropical pioneer tree species without any type of food reward on Barro Colorado Island, Panama. This indicates that ants may alter the recruitment dynamics of more plant species than previously thought broadening the impact of this important ecosystem service.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Ecol, Evol, Conservation Biol

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2019

Author dc:creator

• Ruzi, Selina Ariel

Contributors dc:contributor

• Suarez, Andrew V.
• Dalling, James W.
• Davis, Adam S.
• Hanks, Lawrence M.

• Barro Colorado Island
• seed dispersal
• plant communities
• soil seed bank
• forest regeneration
• ant communities
• Formicidae
• chemical ecology
• seed fate

Statement dc:rights

• Copyright 2019 Selina A Ruzi

Language dc:language

en

Handle dc:identifier

http://hdl.handle.net/2142/105007

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/105007