Community Structure and Ecological Specialization in Plant-Ant Interactions

149 Pages·2016·7.07 MB·English

by  Paola Barriga

UUnniivveerrssiittyy ooff AArrkkaannssaass,, FFaayyeetttteevviillllee
SScchhoollaarrWWoorrkkss@@UUAARRKK
Graduate Theses and Dissertations
12-2012
CCoommmmuunniittyy SSttrruuccttuurree aanndd EEccoollooggiiccaall SSppeecciiaalliizzaattiioonn iinn PPllaanntt--AAnntt
IInntteerraaccttiioonnss
Paola Barriga
University of Arkansas, Fayetteville
Follow this and additional works at: https://scholarworks.uark.edu/etd
Part of the Biology Commons, Entomology Commons, and the Plant Biology Commons
CCiittaattiioonn
Barriga, P. (2012). Community Structure and Ecological Specialization in Plant-Ant Interactions. Graduate
Theses and Dissertations Retrieved from https://scholarworks.uark.edu/etd/625
This Dissertation is brought to you for free and open access by ScholarWorks@UARK. It has been accepted for
inclusion in Graduate Theses and Dissertations by an authorized administrator of ScholarWorks@UARK. For more
information, please contact [email protected].
COMMUNITY STRUCTURE AND ECOLOGICAL SPECIALIZATION IN
PLANT-ANT INTERACTIONS
COMMUNITY STRUCTURE AND ECOLOGICAL SPECIALIZATION IN
PLANT-ANT INTERACTIONS

A dissertation submitted in partial fulfillment
of the requirement for the degree of
Doctor of Philosophy in Biology

By

Paola A. Barriga
Pontificia Universidad Católica del Ecuador
Bachelor of Science in Biology, 2000

December 2012
University of Arkansas
ABSTRACT

Positive associations among species have contributed to the maintenance of biodiversity. These
interactions are typically studied in pairwise fashion where two interacting organisms are the
focus. This dissertation uses network theory to analyze positive plant-ant associations in three
Neotropical forests. Obligate plant-ant mutualisms were used, where plants host the ants in
domatia and provide food bodies while the ants protect the plants and can feed them. A network
approach was used to depict all obligate plant-ant interactions within a community. The main
questions asked at the community level were: 1) Do network structure and levels of
specialization change geographically and, 2) What is the level of resilience of these associations
if plants become extinct? I found that network structure and levels of specialization in three
forests do not vary and that these associations are not resilient to host plant loss. In a second
project I explored if traits of plants that host ants change between lowland and pre-montane
tropical forests and if the differences impact plant-ant associations. Stable isotope analyses of
plants and ants, in addition to plant measurements such as specific leaf area, trichome number,
nitrogen per area and leaf thickness, were used. Plant traits differed by locale and by plant
species. Location, but not ant species, affected herbivory. Finally, I explored the influence of ant
metamorphosis, fat body and diet on stable isotope measurements. Stable isotope analysis is
commonly used in ecological studies to determine trophic structure. However, the physiology of
organisms analyzed can influence the results obtained. Fire ant colonies were used to explore if
metamorphosis, fat body extraction and diet type impact isotopic signatures. Laboratory reared
fire ant colonies were maintained with cricket and a sucrose diet. The addition of tuna to the diet
was tested on additional colonies. Ant fats were dissolved using hexane-isopropanol or 95%
ethanol. Metamorphosis had a significant effect only on δ15N and the availability of tuna
produced further shifts in isotope ratios for all developmental stages. Treatment with organic
solvents had no effect on δ13C, but resulted in enriched d15N values.
This dissertation is approved for recommendation
to the Graduate Council.

Dissertation Director:

_________________________________________
Dr. Cynthia L. Sagers

Dissertation Committee:

___________________________________________
Dr. William J. Etges

___________________________________________
Dr. Gary R. Huxel

____________________________________________
Dr. Phyllis D. Coley
DISSERTATION DUPLICATION RELEASE

I hereby authorize the University of Arkansas Libraries to duplicate this dissertation when
needed for research and/or scholarship.

Agreed ____________________________________________
Paola A. Barriga

Refused _____________________________________________
Paola A. Barriga
ACKNOWLEDGMENTS

Funding for this dissertation came from WWF’s (World Wildlife Fund) Russell E. Train
Education for Nature Program, the Organization for Tropical Studies (Glaxo Fund), Sigma Xi
Grants-in-Aid, and a Dissertation Research Award, Fulbright College of Arts and Sciences,
University of Arkansas to PB, and NSF Office of International Science and Education grant #
0813594 to C. Sagers and N. Garwood. Support as a Teaching Assistantship was granted from
the Department of Biological Sciences at the University of Arkansas.
I acknowledge J. Trager, A. Wild, D. Donoso, J. Longino, W. Mackay for ant
identifications/verifications, C. C. Berg, F. Michellangeli, D. Penneys, H. van der Weff, J.
Gonzalez and J. P. Latorre for plant identification/verification. G. Alvia, E. Bellota and, R.
Gonzales for field assistance, A. Smith for barcode cooperation, K. Kunn for her observations on
Myrmelachista flavocotea at La Selva and A. Barragán, H. Navarrete, OTS-Peru, OTS-Costa
Rica, and staff at these research stations for help with logistics and collecting permits. I also wish
to thank my colleagues of the University of Arkansas Stable Isotope Lab for sample processing
and to A. Dowling for the use of his equipment.
I thank N. Blüthgen, P. Guimarães, P. Jordano, R. Colwell, E. LeBrun, L. Hart, S.
Letcher, J. Stenken, T. Brenes-Arguedas, J. L. Hamrick, and M. Pires for discussion, comment
and advice, and my graduate committee, W. J. Etges, G. R. Huxel, P. D. Coley, C. L. Sagers for
their input. K. Polasky took care of my fire ant colonies. I thank to E. Gbur, J. Ludlam, C.
Dormann, S. Lehnen, K. Thompson and G. Petris for statistical and programming advise. The
Ministerio del Ambiente in Ecuador, the Ministerio de Agricultura in Perú and the Ministerio de
Ambiente y Enegía in Costa Rica approved permits to do this research. Finally, special thanks go
out to my family and friends.
DEDICATION

The journey to obtain this degree is dedicated to my grandparents Estuardo and María
Esthela, my parents Víctor Hugo and Martha Susana, to Connie Tharel, William Eklund, my
siblings and my sweet protector.
TABLE OF CONTENTS
1. INTRODUCTION………………………………………………………………………...1
Literature cited …………………………………………………………………....…..9
2. Community structure and ecological specialization in plant-ant interactions ……..……13
Abstract…………………………………………………………………………........14
Introduction…………………………………………………………………………..16
Methods………………………………………………………………………………20
Results……………………………………………………………………………......27
Discussion……………………………………………………………………………32
Acknowledgements………………………………………………………………......40
Literature cited……………………………………………………………………….41
Tables………………………………………………………………………………...47
Figures………………………………………………………………………………..56
Appendix 2.1…………………………………………………………………………65
Appendix 2.2…………………………………………………………………………66
3. Functional trait variation and ant specialization in two plant-ant species in Costa Rica...67
Abstract………………………………………………………………………………68
Introduction…………………………………………………………………………..70
Methods……………………………………………………………………………....72
Results………………………………………………………………………………..76
Discussion……………………………………………………………………………80
Acknowledgements…………………………………………………………………..84
Literature cited……………………………………………………………………….85