Date on Master's Thesis/Doctoral Dissertation

8-2021

Document Type

Doctoral Dissertation

Degree Name

Ph. D.

Department

Biology

Degree Program

Biology, PhD

Committee Chair

Yanoviak, Stephen

Committee Member

Adams, Rachelle

Committee Member

Christian, Natalie

Committee Member

Eason, Perri

Committee Member

Emery, Sarah

Author's Keywords

Canopy ants; neotropics; eavesdropping; competition; landscape ecology; alarm pheromones

Abstract

This dissertation explores the behavior and ecology of a conspicuous and behaviorally dominant ant species in the tropical rainforest of Panama. Competition with aggressive species is an important factor that shapes local community structure. Eavesdropping on the chemical communication systems of such behaviorally dominant species can help heterospecific species to avoid negative interactions. I review the chemical communication system and known ecological effects of the Neotropical canopy ant, Azteca chartifex/trigona (Chapter 1). There are over 40 known compounds produced by Azteca workers, yet how these compounds impact heterospecific species is unclear in many circumstances. I assessed if heterospecific species respond to A. trigona pheromones by exposing workers of 29 canopy ant species to A. trigona alarm pheromones (Chapter 2). Seven species showed distinct responses to A. trigona pheromones and responses were not associated with phylogeny. The pheromones produced near ant nests may additionally be a reliable source for eavesdropping species and I used open-air sampling techniques to determine whether the air space surrounding A. trigona carton nests has a distinct chemical composition (Chapter 3). The air around disturbed A. trigona nests had higher concentrations of compounds associated with worker alarm pheromones, whereas undisturbed nests were chemically indistinguishable from the surrounding forest air. Azteca trigona workers aggressively outcompete for some resources and I experimentally assessed the effects of A. trigona on the composition of resident and colonizing ants by installing artificial nests in 28 tree crowns (Chapter 4). The presence of A. trigona did not affect the colonization frequency of artificial nests nor species composition of the resident ants in a tree; however, species composition of nest occupants differed between trees and nests located within the foraging territories of A. trigona were colonized less frequently. Finally, I determined if A. trigona was affected by landscape scale factors, including liana presence and canopy height (Chapter 5). A. trigona nests were more frequent in taller trees within older forests and had smaller colony sizes in liana removal plots. Collectively, the results summarized in this dissertation improves our understanding of canopy ant interactions and distributions in a tropical forest.

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